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A single bout of low-frequency electroacupuncture (EA) causing muscle contractions increases whole-body glucose uptake in insulin-resistant rats. We explored the underlying mechanism of this finding and whether it can be translated into clinical settings. Changes in glucose infusion rate (GIR) were measured by euglycemic-hyperinsulinemic clamp during and after 45 min of low-frequency EA in 21 overweight/obese women with polycystic ovary syndrome (PCOS) and 21 controls matched for age, weight, and body mass index (experiment 1) and in rats receiving autonomic receptor blockers (experiment 2). GIR was higher after EA in controls and women with PCOS. Plasma serotonin levels and homovanillic acid, markers of vagal activity, decreased in both controls and patients with PCOS. Adipose tissue expression of pro-nerve growth factor (NGF) decreased, and the mature NGF/proNGF ratio increased after EA in PCOS, but not in controls, suggesting increased sympathetic-driven adipose tissue metabolism. Administration of alpha-/beta-adrenergic receptor blockers in rats blocked the increase in GIR in response to EA. Muscarinic and dopamine receptor antagonist also blocked the response but with slower onset. In conclusion, a single bout of EA increases whole-body glucose uptake by activation of the sympathetic and partly the parasympathetic nervous systems, which could have important clinical implications for the treatment of insulin resistance.-Benrick, A., Kokosar, M., Hu, M., Larsson, M., Maliqueo, M., Marcondes, R. R., Soligo, M., Protto, V., Jerlhag, E., Sazonova, A., Behre, C. J., Hojlund, K., Thoren, P., Stener-Victorin, E. Autonomic nervous system activation mediates the increase in whole-body glucose uptake in response to electroacupuncture.

H5 and H7 subtypes of low pathogenicity avian influenza viruses (LPAIVs) have the potential to evolve into highly pathogenic avian influenza viruses (HPAIVs), causing high mortality in galliforme poultry with substantial economic losses for the poultry industry. This study provides direct evidence of H7N7 LPAIV mutation to HPAIV on a single poultry premises during an outbreak that occurred in June 2008 in free range laying hens in Oxfordshire, UK. We report the first detection of a rare di-basic cleavage site (CS) motif (PEIPKKRGLF), unique to galliformes, that has previously been associated with a LPAIV phenotype. Three distinct HPAIV CS sequences (PEIPKRKKRGLF, PEIPKKKKRGLF and PEIPKKKKKKRGLF) were identified in the infected sheds suggesting molecular evolution at the outbreak premises. Further evidence for H7N7 LPAIV preceding mutation to HPAIV was derived by examining clinical signs, epidemiological descriptions and analysing laboratory results on the timing and proportions of seroconversion and virus shedding at each infected shed on the premises. In addition to describing how the outbreak was diagnosed and managed via statutory laboratory testing, phylogenetic analysis revealed reassortant events during 2006–2008 that suggested likely incursion of a wild bird origin LPAIV precursor to the H7N7 HPAIV outbreak. Identifying a precursor LPAIV is important for understanding the molecular changes and mechanisms involved in the emergence of HPAIV. This information can lead to understanding how and why only some H7 LPAIVs appear to readily mutate to HPAIV.

Summary Field canine coronaviruses (CCVs) identified during a series of outbreaks of gastroenteritis in Swedish dogs were subjected to genetic analysis involving the open reading frame 1b (ORF1b) and the membrane (M) and spike (S) protein genes. Four field viruses originating from the Stockholm region presented identical sequences and segregated separately from other CCVs characterized so far and from GOT/05, the variant recovered in Western Sweden. A recombinant origin of the fifth virus identified in the Stockholm region is suggested. In addition, the five viruses originating from the same geographical area displayed atypical 5′ S gene sequences.

Summary. Coronaviruses are etiologic agents of respiratory and enteric diseases in humans and in animals. In this study, a one-step real-time reverse transcription-polymerase chain reaction (RT-PCR) assay based on SYBR Green chemistry and degenerate primers was developed for the generic detection of coronaviruses. The primers, designed in the open reading frame 1b, enabled the detection of 32 animal coronaviruses including strains of canine coronavirus, feline coronavirus, transmissible gastroenteritis virus (TGEV), bovine coronavirus (BCoV), murine hepatitis virus (MHV) and infectious bronchitis virus (IBV). A specific amplification was also observed with the human coronaviruses (HCoV) HCoV-NL63, HCoV-OC43, HCoV-229E and severe acute respiratory syndrome coronavirus (SARS-CoV). The real-time RT-PCR detected down to 10 cRNA copies from TGEV, BCoV, SARS-CoV and IBV. In addition, the assay exhibited a high sensitivity and specificity on clinical samples from different animal species. The developed assay represents a potential tool for laboratory diagnostics and for detecting still uncharacterized coronaviruses.

Objective—Neutrophil gelatinase-associated lipocalin (NGAL) modulates the activity of matrix metalloproteinase (MMP) 9, an important mediator of vascular remodeling and plaque instability in atherosclerosis. This study aimed to analyze the expression of NGAL in atherosclerotic plaques and myocardial infarction (MI).Methods and Results—Atherosclerotic apolipoprotein E (apoE)−/−× low-density lipoprotein receptor (LDLR)−/−and C57BL/6J control mice were exposed to brief hypoxic stress (10 minutes of 10% oxygen). Expression of the mouse NGAL homolog (24p3) and MMP-9 was analyzed 48 hours later by quantitative RT-PCR, immunohistochemistry, and zymography. Hypoxic stress increased NGAL/24p3 mRNA in the cardiac vasculature. NGAL/24p3 was also increased in atherosclerotic plaques of apolipoprotein E−/−× LDLR−/−mice compared with C57BL/6J mice. Mice developing MI exhibited the highest plaque mRNA expression of NGAL/24p3 and MMP-9. Zymography revealed strong proteolytic activity in areas rich in 24p3 and MMP-9 protein. Immunohistochemistry performed on human carotid endarterectomy specimens and control tissue from the internal mammary artery showed colocalization of MMP-9 and NGAL with macrophages in the atherosclerotic plaques.Conclusions—NGAL/24p3 is increased in atherosclerotic plaques and MI. Colocalization with MMP-9 in areas with high-proteolytic activity suggests a role for NGAL/24p3 in modulating the MMP-9-mediated remodeling of plaques and infarcted hearts.

Congenital heart block develops in fetuses after placental transfer of Ro/SSA autoantibodies from rheumatic mothers. The condition is often fatal and the majority of live-born children require a pacemaker at an early age. The specific antibody that induces the heart block and the mechanism by which it mediates the pathogenic effect have not been elucidated. In this study, we define the cellular mechanism leading to the disease and show that maternal autoantibodies directed to a specific epitope within the leucine zipper amino acid sequence 200–239 (p200) of the Ro52 protein correlate with prolongation of fetal atrioventricular (AV) time and heart block. This finding was further confirmed experimentally in that pups born to rats immunized with p200 peptide developed AV block. p200-specific autoantibodies cloned from patients bound cultured cardiomyocytes and severely affected Ca2+ oscillations, leading to accumulating levels and overload of intracellular Ca2+ levels with subsequent loss of contractility and ultimately apoptosis. These findings suggest that passive transfer of maternal p200 autoantibodies causes congenital heart block by dysregulating Ca2+ homeostasis and inducing death in affected cells.

DeltaFosB is a transcription factor that accumulates in a region-specific manner in the brain after chronic perturbations. For example, repeated administration of drugs of abuse increases levels of DeltaFosB in the striatum. In the present study, we analyzed the effect of spontaneous wheel running, as a model for a natural rewarding behavior, on levels of DeltaFosB in striatal regions. Moreover, mice that inducibly overexpress DeltaFosB in specific subpopulations of striatal neurons were used to study the possible role of DeltaFosB on running behavior. Lewis rats given ad libitum access to running wheels for 30 d covered what would correspond to approximately 10 km/d and showed increased levels of DeltaFosB in the nucleus accumbens compared with rats exposed to locked running wheels. Mice that overexpress DeltaFosB selectively in striatal dynorphin-containing neurons increased their daily running compared with control littermates, whereas mice that overexpress DeltaFosB predominantly in striatal enkephalin-containing neurons ran considerably less than controls. Data from the present study demonstrate that like drugs of abuse, voluntary running increases levels of DeltaFosB in brain reward pathways. Furthermore, overexpression of DeltaFosB in a distinct striatal output neuronal population increases running behavior. Because previous work has shown that DeltaFosB overexpression within this same neuronal population increases the rewarding properties of drugs of abuse, results of the present study suggest that DeltaFosB may play a key role in controlling both natural and drug-induced reward.

Thyroid hormone governs a diverse repertoire of physiological functions through receptors encoded in the receptor genes alpha and beta, which each generate variant proteins. In mammals, the alpha gene generates, in addition to the normal receptor TRalpha1, a non-hormone-binding variant TRalpha2 whose exact function is unclear. Here, we present the phenotype associated with the targeted ablation of TRalpha2 expression. Selective ablation of TRalpha2 resulted in an inevitable, concomitant overexpression of TRalpha1. Both TRalpha2 +/- and -/- mice show a complex phenotype with low levels of free T3 and free T4, and have inappropriately normal levels of TSH. The thyroid glands exhibit mild morphological signs of dysfunction and respond poorly to TSH, suggesting that the genetic changes affect the ability of the gland to release thyroid hormones. However, the phenotype of the mutant mice also has features of hyperthyroidism, including decreased body weight, elevated heart rate, and a raised body temperature. Furthermore, TRalpha2-/- and TRalpha2+/- mice are obese and exhibit skeletal alterations, associated with a late-onset growth retardation. The results thus suggest that the overexpression of TRalpha1 and the concomitant decrease in TRalpha2 expression lead to a mixed hyper- and hypothyroid phenotype, dependent on the tissue studied. The phenotypes suggest that the balance of TRalpha1:TRalpha2 expressed from the TRalpha gene provides an additional level of tuning the control of growth and homeostasis in mammalian species.

The experiences of a veterinary research and diagnostic laboratory are summarized on the development and application of the PCR to diagnose a wide range of viral diseases in animals. The group started the routine diagnostic application of the PCR as early as 1988 and today a total of 35 nested PCR assays are in routine use for the detection of 15 DNA and 20 RNA viruses. Special tools and laboratory practice were applied to avoid false-positive results, while false-negatives are avoided by internal controls (mimics). At present, the classical nested PCR methods are being replaced by real-time TaqMan and molecular beacon assays and the multiplex real-time PCR detection of viruses is also under development. By direct sequencing of the PCR products, phylogeny studies are performed and molecular epizootiology results are provided for rapid and exact identification of virus variants. Molecular epizootiology also contributes to trace the routes of virus spreading on large geographic areas. Recently, large efforts have been made to follow the recommendations of Office International des Epizooties for the standardization and international harmonization of the molecular diagnostic assays.

Septic shock, a major cause of death, is characterized by a pathophysiologic increased production of nitric oxide (NO), which leads to vasodilation and myocardial toxicity. Septic Escherichia coli frequently express proteinaceous curli fibers. In this study, curliated E. coli induced high levels of NO by directly inducing type 2 nitric oxide synthase (NOS2) both in vitro and in vivo. More severe hypotension and higher plasma nitrite/nitrate levels were seen in wild type mice systemically infected with curliated E. coli than in animals infected with E. coli mutants that lacked curli proteins. Blood pressure remained stable in NOS2-deficient mice with curliated bacteria. Increased heart rates, transient hypothermia, and loss of gross activity were seen in all mice, regardless of curli expression. Study results suggest that expression of curli fibers by E. coli activates the NO/NOS2 arm of the innate immune system, which leads to a significant fall in blood pressure.

1. Mice lacking the apolipoprotein E and low density lipoprotein receptor genes (E degrees xLDLR degrees ) develop atherosclerosis and endothelial dysfunction. The aim of this study was to characterize the roles of L-arginine and tetrahydrobiopterin (BH(4)) for endothelium-dependent relaxation and the changes in the vasoconstrictor response to endothelin-1 (ET-1) in thoracic aortic rings of E degrees xLDLR degrees mice. 2. Histological examination revealed severe atherosclerosis of the thoracic aorta of E degrees xLDLR degrees mice. Relaxations induced by acetylcholine (Ach), but not that to sodium nitroprusside, were significantly impaired in E degrees xLDLR degrees mice compared to control mice indicating attenuated endothelium-dependent relaxations. 3. Preincubation with the nitric oxide (NO) substrate L-arginine did not affect, whereas the co-factor for NO synthase, BH(4), slightly improved the relaxations induced by Ach. Combined preincubation with L-arginine and BH(4) induced a pronounced enhancement of Ach-induced relaxations in E degrees xLDLR degrees mice. The relaxations induced by Ach in E degrees xLDLR degrees mice in the presence of L-arginine and BH(4) were not different from those observed in control mice. 4. Preincubation with superoxide dismutase did not affect Ach-induced relaxations in aorta from E degrees xLDLR degrees mice. 5. The contractile response to ET-1 was enhanced in E degrees xLDLR degrees mouse aorta. The contractions were abolished by the ET(A) receptor antagonist LU 135252. The ET(B) receptor agonist sarafotoxin 6c did not induce contractions or relaxations. 6. It is concluded that endothelial dysfunction of E degrees xLDLR degrees mouse aorta is reversed by combined administration of L-arginine and BH(4). In addition, the ET(A) receptor-mediated vasoconstriction by ET-1 is enhanced in E degrees xLDLR degrees mice.

1. Mice lacking the apolipoprotein E and low density lipoprotein receptor genes (E degrees xLDLR degrees ) develop atherosclerosis. The aim of this study was to investigate changes in endothelium-dependent vasodilation and vasomotion in thoracic aortic rings of E degrees xLDLR degrees mice. 2. K+-induced contractions of the aorta from E degrees xLDLR degrees mice were stronger than those from control mice. The sensitivity of E degrees xLDLR degrees aorta to phenylephrine (PE) was decreased but the maximal contractions were increased. Acetylcholine-induced, but not sodium nitroprusside-induced, relaxations of E degrees xLDLR degrees aorta was decreased. 3. PE induced rhythmic activity in both E degrees xLDLR degrees and control aorta but the amplitude was larger in E degrees xLDLR degrees than in control mice. PE-induced rhythmic activity in both E degrees xLDLR degrees and control aorta was augmented by increase in extracellular Ca2+-concentration, but was abolished by removal of the endothelium, the nitric oxide (NO) synthase inhibitor N-nitro-L-arginine methyl ester, the guanylate cyclase inhibitor LY-83583, high K+ solution and ryanodine. 4. 4-Aminopyridine, a voltage-dependent potassium (KV) channel blocker, increased basal tension and induced rhythmic activity in E degrees xLDLR degrees aorta but not in control aorta. 5. The Ca2+-activated potassium (KCa) channel blockers tetraethylammonium and charybdotoxin abolished PE-induced rhythmic activity in E degrees xLDLR degrees aorta. 6. In conclusion, opening of Kv channels in E degrees xLDLR degrees mice aorta is reduced and it is susceptible to be depolarized resulting in Ca2+ entry. The vascular smooth muscle is then dependent on compensatory mechanisms to limit Ca2+-entry. Such mechanisms may be decreased sensitivity to vasoconstrictors, or increased opening of KCa channels by NO via a cyclic GMP-dependent mechanism.

Queen mating frequency was studied in the European hornet, Vespa crabro, by analyzing four DNA microsatellite loci in 20 workers from each of 14 nests. Queens were found to be predominantly singly mated (9/14), although double (4/14) and triple mating (1/14) also occurred. For most multiply mated queens, paternity was significantly biased with the majority male fathering on average 80% of the female offspring. The population-wide effective mating frequency was therefore low (1.11), and sister-sister relatedness high (0.701 ± 0.023 SE). Low effective mating frequency in Vespa, in combination with data from other vespines, suggests that high paternity frequency is derived in the group. Some problems with the non-detection of fathers, where the queen was not sampled or shared alleles with males, are analyzed.

Thyroid hormone, acting through several nuclear hormone receptors, plays important roles in thermogenesis, lipogenesis and maturation of the neonatal brain. The receptor specificity for mediating these effects is largely unknown, and to determine this we developed mice lacking the thyroid hormone receptor TR alpha 1. The mice have an average heart rate 20% lower than that of control animals, both under normal conditions and after thyroid hormone stimulation. Electrocardiograms show that the mice also have prolonged QRS- and QTend-durations. The mice have a body temperature 0.5 degrees C lower than normal and exhibit a mild hypothyroidism, whereas their overall behavior and reproduction are normal. The results identify specific and important roles for TR alpha 1 in regulation of tightly controlled physiological functions, such as cardiac pacemaking, ventricular repolarisation and control of body temperature.

An evolutionary understanding of the causes, correlates and consequences of multiple paternity in eusocial Hymenoptera (all ants, some bees and some wasps) relies on accurate estimation of this parameter at the species, population and colony level. We developed dinucleotide microsatellite DNA markers in order to study in detail the degree of multiple paternity in a population of the monogynous Panamanian leafcutter ant Atta colombica. These microsatellite markers were highly polymorphic such that nondetection caused by finite allelic diversity was very low (0.016). Hence, accurate information on the patterns of multiple paternity could be obtained. Genetic analysis revealed that in 33 out of 36 colonies two or more males had contributed genetically to the offspring. The mean number of fathers per colony was 2.6 and the mean effective paternity was 2.31. These are the highest values of effective paternity yet reported for any ant species. We examined the patterns of paternity frequency in young and old colonies to test if within-colony genetic diversity is related to colony survival, but found no support for any relationship. Our results confirm previous nongenetic studies showing high levels of multiple mating by queens of higher leafcutter ants. We discuss our findings in relation to known patterns of polyandry and paternity in other eusocial Hymenoptera.

The life of social insects centers around sedentary colonies that can include individuals belonging to different patrilines or matrilines, with a turnover of reproductives. The colony is a scene for both cooperation and conflicts, and the conceptual framework for the evolution of social life and colony organization is provided by the kin selection theory. Variable molecular markers make it possible to dissect kinship within colonies, identifying patrilines and matrilines and estimating genetic relatednesses. Such markers have been used to test hypotheses on social conflicts between queens and workers (split sex ratio hypothesis), among workers (worker policing hypothesis), and among reproductive females (skew hypothesis). The data from several species of ants, bees, and wasps indicate that workers can obtain information on the genetic heterogeneity of their colonies and use that information to manipulate reproductive decisions. The social structure of colonies and the mode of colony founding affect the population-wide dispersal of sexuals. Populations with multi-queen colonial networks have limited dispersal; females stay in their natal colonies, and mating flights can be restricted. As a result, coexisting queens tend to be related to each other, maintaining the genetic integrity of colonies, and populations become spatially differentiated to an extent that can lead even to socially driven speciation.

Highly pathogenic avian influenza (HPAI) subtype H5N1 is an infectious systemic viral disease that results in high morbidity and mortality in poultry, and has been reported in a wide range of wild bird species during the last few years. An outbreak of HPAI H5N1 occurred in wild birds in Sweden in 2006 that affected several duck species, geese, swans, gulls, and raptors. Tufted ducks ( Aythya fuligula) accounted for the largest number of positive cases and, therefore, were selected for more in-depth histologic and immunohistochemical evaluations. The main histologic lesions associated with the presence of avian influenza antigen were found in the brain, pancreas, and upper respiratory tract. Other tissues in which influenza antigen was variably found included liver, lung, adrenal glands, kidneys, and peripheral nerve ganglia. The current study describes the pathology and viral tissue targeting of H5N1 by using histology, polymerase chain reaction, and immunohistochemistry, and highlights the range and variation in the presentation of the natural disease in tufted ducks.

The early and rapid detection and characterization of specific nucleic acids of medico-veterinary pathogens have proven invaluable for diagnostic purposes. The integration of amplification and signal detection systems, including online real-time devices, have increased speed and sensitivity and greatly facilitated the quantification of target nucleic acids. They have also allowed for sequence characterization using melting or hybridization curves. The newer-generation molecular diagnostic technologies offer, hitherto, unparalleled detection and discrimination methodologies, which are vital for the positive detection and identification of pathogenic agents, as well as the effects of the pathogens on the production of antibodies. The development phase of the novel technologies entails a thorough understanding of accurate diagnosis and discrimination of present and emerging diseases. The development of novel technologies can only be successful if they are transferred and used in the field with a sustainable quality-assured application to allow for the optimal detection and effective control of diseases. The aim of these new tools is to detect the presence of a pathogen agent before the onset of disease. This manuscript focuses mainly on the experiences of two World Organisation for Animal Health collaborating centers in context to molecular diagnosis and molecular epidemiology of transboundary and endemic animal diseases of viral origin, food safety and zoonoses.

Many different polymerase chain reaction (PCR) protocols have been used for detection and characterization of avian influenza (AI) virus isolates, mainly in research settings. Blind ring trials were conducted to determine the most sensitive and specific AI PCR protocols from a group of six European Union (EU) laboratories. In part 1 of the ring trial the laboratories used their own methods to test a panel of 10 reconstituted anonymized clinical specimens, and the best methods were selected as recommended protocols for part 2, in which 16 RNA specimens were tested. Both panels contained H5, H7, other AI subtypes, and non-AI avian pathogens. Outcomes included verification of 1) generic AI identification by highly sensitive and specific M-gene real-time PCR, and 2) conventional PCRs that were effective for detection and identification of H5 and H7 viruses. The latter included virus pathotyping by amplicon sequencing. The use of recommended protocols resulted in improved results among all six laboratories in part 2, reflecting increased sensitivity and specificity. This included improved H5/H7 identification and pathotyping observed among all laboratories in part 2. Details of these PCR methods are provided. In summary, this study has contributed to the harmonization of AI PCR protocols in EU laboratories and influenced AI laboratory contingency planning following the first European reports of H5N1 highly pathogenic AI during autumn 2005.

Many different polymerase chain reaction (PCR) protocols have been used for detection and characterization of avian influenza (AI) virus isolates, mainly in research settings. Blind ring trials were conducted to determine the most sensitive and specific AI PCR protocols from a group of six European Union (EU) laboratories. In part 1 of the ring trial the laboratories used their own methods to test a panel of 10 reconstituted anonymized clinical specimens, and the best methods were selected as recommended protocols for part 2, in which 16 RNA specimens were tested. Both panels contained H5, H7, other AI subtypes, and non-AI avian pathogens. Outcomes included verification of 1) generic AI identification by highly sensitive and specific M-gene real-time PCR, and 2) conventional PCRs that were effective for detection and identification of H5 and H7 viruses. The latter included virus pathotyping by amplicon sequencing. The use of recommended protocols resulted in improved results among all six laboratories in part 2, reflecting increased sensitivity and specificity. This included improved H5/H7 identification and pathotyping observed among all laboratories in part 2. Details of these PCR methods are provided. In summary, this study has contributed to the harmonization of AI PCR protocols in EU laboratories and influenced AI laboratory contingency planning following the first European reports of H5N1 highly pathogenic AI during autumn 2005.

The present study was performed to investigate the role of adenosine A1receptors in regulating blood pressure in conscious mice. Adenosine A1-receptor knockout (A1R−/−) mice and their wild-type (A1R+/+) littermates were placed on standardized normal-salt (NS), high-salt (HS), or salt-deficient (SD) diets for a minimum of 10 days before telemetric blood pressure and urinary excretion measurements in metabolic cages. On the NS diet, daytime and nighttime mean arterial blood pressure (MAP) was 7–10 mmHg higher in A1R−/− than in A1R+/+ mice. HS diet did not affect the MAP in A1R−/− mice, but the daytime and nighttime MAP of the A1R+/+ mice increased by ∼10 mmHg, to the same level as that in the A1R−/−. On the SD diet, day- and nighttime MAP decreased by ∼6 mmHg in both A1R−/− and A1R+/+ mice, although the MAP remained higher in A1R−/− than in A1R+/+ mice. Although plasma renin levels decreased with increased salt intake in both genotypes, the A1R−/− mice had an approximately twofold higher plasma renin concentration on all diets compared with A1R+/+ mice. Sodium excretion was elevated in the A1R−/− compared with the A1R+/+ mice on the NS diet. There was no difference in sodium excretion between the two genotypes on the HS diet. Even on the SD diet, A1R−/− mice had an increased sodium excretion compared with A1R+/+ mice. An abolished tubuloglomerular feedback response and reduced tubular reabsorption can account for the elevated salt excretion found in A1R−/− animals. The elevated plasma renin concentrations found in the A1R−/− mice could also result in increased blood pressure. Our results confirm that adenosine, acting through the adenosine A1receptor, plays an important role in regulating blood pressure, renin release, and sodium excretion.

We have previously shown that atherosclerotic apolipoprotein E-deficient (apoE(-/-)) x LDL receptor-deficient (LDLR(-/-)) mice develop myocardial infarction when exposed to hypoxic stress. This study was performed to assess the role of thrombin and thrombosis in this process. ApoE(-/-) x LDLR(-/-) mice were fed a cholesterol-rich diet for 8 mo and were then subjected to hypoxic stress while receiving isoflurane anesthesia. One group received a bolus dose (5.6 micromol/kg) of the thrombin inhibitor melagatran, and control animals received PBS 10 min before the hypoxic stress. The mice were exposed to 10 min of hypoxia followed by normoxia. Ten minutes after the stress, Alzet pumps delivering melagatran (20 nmol x kg x (-1)min(-1)) or PBS were implanted, and the mice were allowed to recover for 48 h. The cardiac response was analyzed by histology, immunohistochemistry, and serum troponin T assay. All animals showed reversible ECG changes as a sign of ischemia during hypoxic stress, and 50% developed infarctions afterward as judged by troponin T levels. The group that received thrombin inhibitor had significantly lower troponin T and smaller myocardial infarctions than the PBS-treated group. These data show that thrombin generation is an important pathogenetic factor and suggest that coronary thrombosis is involved in myocardial infarction in atherosclerotic mice. Exposure of atherosclerotic mice to hypoxia leads to myocardial infarction through a two-phase pathway in which acute transient ischemia is followed by thrombin-dependent, irreversible, myocardial ischemia and myocardial cell death.

The platelet-derived growth factors are implicated in development of fibrotic reactions and disease in several organs. We have overexpressed platelet-derived growth factor-C in the heart using the alpha-myosin heavy chain promoter and created a transgenic mouse that exhibits cardiac fibrosis followed by hypertrophy with sex-dependent phenotypes. The transgenic mice developed several pathological changes including cardiac fibroblast proliferation and deposition of collagen, hypertrophy, vascular defects, and the presence of Anitschkow cells in the adult myocardium. Male mice developed a hypertrophic phenotype, whereas female mice were more severely affected and developed dilated cardiomyopathy, leading to heart failure and sudden death. The vascular defects initially included dilation of microvessels and vascular leakage. Subsequently, a marked loss of microvessels, formation of large vascular sac-like structures, and an increased density of smooth muscle-coated vessels were observed in the myocardium. In part, the observed vascular changes may be because of an up-regulation of vascular endothelial growth factor in cardiac fibroblasts of the transgenic hearts. This unique animal model reveals that a potent mitogen for cardiac fibroblasts result in an expansion of the interstitium that induce a secondary sex-dependent hypertrophic response in the cardiomyocytes.

Most patients with the syndrome resistance to thyroid hormone (RTH) express a mutant thyroid hormone receptor beta (TRbeta) with transdominant negative transcriptional effects. Since no patient with a mutant TRalpha has been identified, we introduced a point mutation into the mouse thyroid hormone receptor (TRalpha1) locus originally found in the TRbeta gene, that reduces ligand binding 10-fold. Heterozygous 2- to 3-week- old mice exhibit a severe retardation of post-natal development and growth, but only a minor reduction in serum thyroxine levels. Homozygous mice died before 3 weeks of age. Adult heterozygotes overcome most of these defects except for cardiac function abnormalities, suggesting that other factors compensate for the receptor defect. However, the additional deletion of the TRbeta gene in this mouse strain caused a 10-fold increase in serum thyroxine, restored hormonal regulation of target genes for TRs, and rescued the growth retardation. The data demonstrate a novel array of effects mediated by a dominant negative TRalpha1, and may provide important clues for identification of a potentially unrecognized human disorder and its treatment.

Blood vessels express estrogen receptors, but their role in cardiovascular physiology is not well understood. We show that vascular smooth muscle cells and blood vessels from estrogen receptor beta (ERbeta)-deficient mice exhibit multiple functional abnormalities. In wild-type mouse blood vessels, estrogen attenuates vasoconstriction by an ERbeta-mediated increase in inducible nitric oxide synthase expression. In contrast, estrogen augments vasoconstriction in blood vessels from ERbeta-deficient mice. Vascular smooth muscle cells isolated from ERbeta-deficient mice show multiple abnormalities of ion channel function. Furthermore, ERbeta-deficient mice develop sustained systolic and diastolic hypertension as they age. These data support an essential role for ERbeta in the regulation of vascular function and blood pressure.

In the multistep process of leukocyte extravasation, the mechanisms by which leukocytes establish the initial contact with the endothelium are unclear. In parallel, there is a controversy regarding the role for L-selectin in leukocyte recruitment. Here, using intravital microscopy in the mouse, we investigated leukocyte capture from the free flow directly to the endothelium (primary capture), and capture mediated through interactions with rolling leukocytes (secondary capture) in venules, in cytokine-stimulated arterial vessels, and on atherosclerotic lesions in the aorta. Capture was more prominent in arterial vessels compared with venules. In venules, the incidence of capture increased with increasing vessel diameter and wall shear rate. Secondary capture required a minimum rolling leukocyte flux and contributed by ∼20–50% of total capture in all studied vessel types. In arteries, secondary capture induced formation of clusters and strings of rolling leukocytes. Function inhibition of L-selectin blocked secondary capture and thereby decreased the flux of rolling leukocytes in arterial vessels and in large (>45 μm in diameter), but not small (

Background Vascular endothelial growth factors (VEGFs) and their receptors are essential regulators of vasculogenesis and angiogenesis in both embryos and adults. One of the factors with a still unknown physiological function is VEGF-B, which is expressed in many tissues, including the heart. Methods and Results Mice carrying a targeted deletion in the VEGF-B gene were developed. In VEGF-B −/− animals, no gross abnormalities were observed in organs that normally show high expression of VEGF-B, such as the heart, muscle, and kidney. Analysis of heart function by ECG showed that adult VEGF-B −/− mice have an atrial conduction abnormality characterized by a prolonged PQ interval. VEGF- or basic fibroblast growth factor–induced corneal angiogenesis was similar in normal and VEGF-B −/− mice. Conclusions VEGF-B seems to be required for normal heart function in adult animals but is not required for proper development of the cardiovascular system either during development or for angiogenesis in adults.

We recently described a mouse model that reproduces important pathophysiological features of mitochondrial DNA (mtDNA) mutation diseases. The gene for mouse mitochondrial transcription factor A, Tfam (also called mtTFA), a nucleus-encoded key regulator of mtDNA expression, was targeted with loxP sites ( Tfam loxP ) and disrupted in vivo by transgenic expression of cre -recombinase from the muscle creatinine kinase ( Ckmm ) promoter. This promoter is active from embryonic day 13, and the knockouts had normal respiratory chain function in the heart at birth and developed mitochondrial cardiomyopathy postnatally. In this paper, we describe a heart-knockout strain obtained by mating Tfam loxP mice to animals expressing cre -recombinase from the α-myosin heavy chain ( Myhca ) promoter. This promoter is active from embryonic day 8, and the knockouts had onset of mitochondrial cardiomyopathy during embryogenesis. The age of onset of cardiac respiratory chain dysfunction can thus be controlled by temporal regulation of cre -recombinase expression. Further characterization demonstrated that ≈75% of the knockouts died in the neonatal period, whereas, surprisingly, ≈25% survived for several months before dying from dilated cardiomyopathy with atrioventricular heart conduction blocks. Modifying gene(s) affect the life span of the knockouts, because ≈95% of the knockout offspring from an intercross of the longer-living knockouts survived the neonatal period. Thus, the tissue-specific knockouts we describe here not only reproduce important pathophysiological features of mitochondrial cardiomyopathy but also provide a powerful system by which to identify modifying genes of potential therapeutic value.

The specific role of each subtype of thyroid hormone receptor (TR) on skeletal muscle function is unclear. We have therefore studied kinetics of isometric twitches and tetani as well as fatigue resistance in isolated soleus muscles of R-α1- or -β-deficient mice. The results show 20–40% longer contraction and relaxation times of twitches and tetani in soleus muscles from TR-α1-deficient mice compared with their wild-type controls. TR-β-deficient mice, which have high thyroid hormone levels, were less fatigue resistant than their wild-type controls, but contraction and relaxation times were not different. Western blot analyses showed a reduced concentration of the fast-type sarcoplasmic reticulum Ca2+-ATPase (SERCa1) in TR-α1-deficient mice, but no changes were observed in TR-β-deficient mice compared with their respective controls. We conclude that in skeletal muscle, both TR-α1 and TR-β are required to get a normal thyroid hormone response.

Neuropeptide Y (NPY), a 36-amino-acid peptide widely expressed in the brain is involved in many physiological responses, including hypothalamic control of food intake and cardiovascular homeostasis. NPY mediates its effects through binding to the Y1, Y2 and Y5 G-protein-coupled receptors. Little is known of the role of the Y2 receptor in mediating the different NPY effects. We inactivated the Y2 receptor subtype in mice and found that these mice developed increased body weight, food intake and fat deposition. The null mutant mice showed an attenuated response to leptin administration but a normal response to NPY-induced food intake and intact regulation of re-feeding and body weight after starvation. An absence of the Y2 receptor subtype also affected the basal control of heart rate, but did not influence blood pressure. These findings indicate an inhibitory role for the Y2 receptor subtype in the central regulation of body weight and control of food intake.

We have examined the effects of chronic voluntary running for 30 d on the levels of nerve growth factor inducilble-B (NGFI-B) and neuron-derived orphan receptor 1 (NOR1) mRNAs in Fischer and Lewis rats. The aim was to compare the addiction-prone Lewis rat strain to the Fischer strain in a plausible model for natural reward. The Lewis strain ran markedly more than the Fischer strain, as indicated by the length of running per day when given free access to running wheels. Both strains progressively increased their amount of daily running. By day 14, Lewis rats had reached a maximal level corresponding to 10 km/d, which slowly decreased to approximately 8 km/d. Fischer rats ran considerably less, averaging approximately 1. 5 km/d by day 30. After 30 d of running, levels of mRNA encoding NGFI-B and Nor1 were decreased in cerebral cortex in Lewis but not Fischer rats. The downregulation of NGFI-B mRNA in Lewis rats could not be attenuated by the opioid receptor antagonist naloxone. Instead, naloxone by itself downregulated NGFI-B in striatum and cerebral cortex in both strains. In contrast, naloxone had no effect on Nor1 mRNA levels, although the running-induced downregulation of Nor1 was, in most cases, attenuated by naloxone. Data from the present study suggest that the same genetic factors contributing to the drug addiction-prone behavior of Lewis rats also control the excessive running behavior and that this coincides with downregulation of transcription factors of the NGFI-B family.

Myocardial infarction is linked to atherosclerosis, yet the sequence leading from silent coronary atherosclerosis to acute myocardial infarction has remained unclear. Here we show that hypercholesterolemic apolipoprotein E −/− low density lipoprotein receptor −/− mice develop not only coronary atherosclerosis but also myocardial infarction. Exposure of mice to mental stress or hypoxia led to acute ischemia, which, in a large proportion of the mice, was followed by electrocardiographic changes, leakage of troponin T, and loss of dehydrogenase from the myocardium, all indicative of acute myocardial infarction. Apoptotic death of cardiomyocytes was followed by inflammation and fibrosis in the heart. All these pathological changes could be prevented by a blocker of the endothelin type A receptor. Thus, stress elicits myocardial infarction through endothelin receptor signaling in coronary atherosclerosis caused by hypercholesterolemia.

Background Although the important role of the non-structural 1 (NS) gene of influenza A in virulence of the virus is well established, our knowledge about the extent of variation in the NS gene pool of influenza A viruses in their natural reservoirs in Europe is incomplete. In this study we determined the subtypes and prevalence of influenza A viruses present in mallards in Northern Europe and further analysed the NS gene of these isolates in order to obtain a more detailed knowledge about the genetic variation of NS gene of influenza A virus in their natural hosts. Results A total number of 45 influenza A viruses of different subtypes were studied. Eleven haemagglutinin- and nine neuraminidase subtypes in twelve combinations were found among the isolated viruses. Each NS gene reported here consisted of 890 nucleotides; there were no deletions or insertions. Phylogenetic analysis clearly shows that two distinct gene pools, corresponding to both NS allele A and B, were present at the same time in the same geographic location in the mallard populations in Northern Europe. A comparison of nucleotide sequences of isolated viruses revealed a substantial number of silent mutations, which results in high degree of homology in amino acid sequences. The degree of variation within the alleles is very low. In our study allele A viruses displays a maximum of 5% amino acid divergence while allele B viruses display only 2% amino acid divergence. All the viruses isolated from mallards in Northern Europe possessed the typical avian ESEV amino acid sequence at the C-terminal end of the NS1 protein. Conclusion Our finding indicates the existence of a large reservoir of different influenza A viruses in mallards population in Northern Europe. Although our phylogenetic analysis clearly shows that two distinct gene pools, corresponding to both NS allele A and B, were present in the mallards populations in Northern Europe, allele B viruses appear to be less common in natural host species than allele A, comprising only about 13% of the isolates sequenced in this study.

Background The analysis of the nonstructural (NS) gene of the highly pathogenic (HP) H5N1 avian influenza viruses (AIV) isolated in Sweden early 2006 indicated the co-circulation of two sub-lineages of these viruses at that time. In order to complete the information on their genetic features and relation to other HP H5N1 AIVs the seven additional genes of twelve Swedish isolates were amplified in full length, sequenced, and characterized. Results The presence of two sub-lineages of HP H5N1 AIVs in Sweden in 2006 was further confirmed by the phylogenetic analysis of approximately the 95% of the genome of twelve isolates that were selected on the base of differences in geographic location, timing and animal species of origin. Ten of the analyzed viruses belonged to sub-clade 2.2.2. and grouped together with German and Danish isolates, while two 2.2.1. sub-clade viruses formed a cluster with isolates of Egyptian, Italian, Slovenian, and Nigerian origin. The revealed amino acid differences between the two sub-groups of Swedish viruses affected the predicted antigenicity of the surface glycoproteins, haemagglutinin and neuraminidase, rather than the nucleoprotein, polymerase basic protein 2, and polymerase acidic protein, the main targets of the cellular immune responses. The distinctive characteristics between members of the two subgroups were identified and described. Conclusion The comprehensive genetic characterization of HP H5N1 AIVs isolated in Sweden during the spring of 2006 is reported. Our data support previous findings on the coincidental spread of multiple sub-lineage H5N1 HPAIVs via migrating aquatic birds to large distance from their origin. The detection of 2.2.1. sub-clade viruses in Sweden adds further data regarding their spread in the North of Europe in 2006. The close genetic relationship of Swedish isolates sub-clade 2.2.2. to the contemporary German and Danish isolates supports the proposition of the introduction and spread of a single variant of 2.2.2. sub-clade H5N1 avian influenza viruses in the Baltic region. The presented findings underline the importance of whole genome analysis.

Summary: Infusion of felodipine and verapamil in increasing doses to anesthetized spontaneously hypertensive rats induced a progressive fall in arterial blood pressure (BP). To estimate the cardiac action of the different drugs, we also measured changes in cardiac output (CO) and velocity of flow (dF/dT) by a Doppler flow probe placed on the ascending aorta. Infusion of verapamil induced a parallel decrease in mean arterial BP, CO, and cardiac inotropy (as estimated by max. dF/dT). In contrast, upon felodipine administration, the decrease in arterial BP was accompanied by an initial small rise in dF/dT. A decrease in dF/dT was observed only after high doses of felodipine, which cause pronounced levels of hypotension.

The silicon used in the present study was Bisico S4i, which consists of dual chamber tubes filled with two components. Silicon S4i is loaded in a dispenser and its outlet is connected to a nozzle and a small tip (these all come from Bisico, Germany). When the dispenser is triggered, the two components flow into the nozzle, mix there, and then go out through the tip. The mixed silicon hardens in room temperature within a few minutes. Spontaneously hypertensive rats (SHR) (260 ? 9 g) were from Mollegaard Breeding Centre (Skensved, Denmark). They were given standard rat pellets and tap water ad libitum and housed in the animal unit of the department for at least 1 week (22” C, 60% humidity and 12:12 of light-dark cycle). The experiments were approved by the Animal Ethical Committee at Karolinska Institute, Stockholm, Sweden. The rats were anesthetised with methohexital (Brietal) 60 mg/kg i.p.. Body temperature was kept at about

In this paper we discuss recent experimental and clinical findings which lead us to propose that prolonged rhythmic exercise can activate central opioid systems by triggering increased discharge from mechanosensitive afferent nerve fibers (Group III or A-delta) arising from contracting skele

We studied the effect of the dihydropyridine calcium antagonists felodipine nimodipine on perfusion of the cerebral cortex in the spontaneously hypertensive rat (SHR). Nimodipine and felodipine were infused in equipotent doses in chloralose-anaesthetized SHR. During the infusion of a low and an intermediate dose of felodipine, mean arterial blood pressure was lowered to 90.5 +/- 1.5 and 67.1 +/- 2.9% of the control level. The nimodipine infusion lowered mean arterial pressure to 85.7 +/- 2.0 and 59.7 +/- 2.4% of the control level. At these pressures, cortical perfusion as measured by a laser Doppler flow technique increased to 123.5 +/- 6.9 and 130 +/- 5.4% of the control level during the felodipine infusion and to 114.0 +/- 1.6 and 122.3 +/- 3.2% of the control level during the nimodipine infusion. When these results were compared by covariance analysis of variance, felodipine induced a significantly greater change in cortical perfusion. At the highest dose of felodipine and nimodipine there was no significant difference in cortical perfusion between the two drugs. The administration of felodipine induced a decrease in cerebrovascular autoregulation. However, this impairment of cerebrovascular autoregulation is not likely to trigger cerebral hypoperfusion. Thus, for a mean arterial pressure of 55 mmHg, the laser Doppler-measured cortical flow was, if anything, elevated after felodipine administration.

1 Mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded in conscious spontaneously hypertensive rats (SHR). 2 Infusion of metoprolol (4 mumol kg-1 h-1) or propranolol (1.5 mumol kg-1 h-1) reduced HR and significantly increased RSNA. 3 Administration of metoprolol caused a sustained decrease of MAP starting in the third hour of infusion. In contrast, administration of propranolol induced a biphasic response in MAP. It is suggested that the increase of RSNA after both beta-adrenoceptor blocking drugs is due to a decrease in arterial baroreceptor activity.

Cerebral blood flow (CBF, by laser Doppler flowmetry) and extracellular cortical concentrations (by microdialysis) of adenosine, inosine, xanthine, hypoxanthine, and lactate were measured together with somatosensory evoked potentials (SEP) in chloralose-anaesthetized spontaneously hypertensive rats (SHR) during relative cerebral ischemia induced by hypotensive hemorrhage. Reduction of mean arterial blood pressure (MABP) to 40–50 mm Hg, which decreased SEP to about 50% of prebleeding control level, decreased CBF only to about 75% of control due to cerebrovascular “autoregulation.” A secondary, marked rise in cerebrovascular resistance (CVR) occurred after about 15 min in parallel with a striking increase in heart rate (after initial bradycardia). This late rise in heart rate is probably elicited by relative ischemia in medullary centers. The increase in CVR might indicate increased sympathetic nerve activity to the circle of Willis and large cerebral arteries. Cortical lactate increased initially but started to decline after about 30 min, and after 2 h it was not significantly higher than control. Cortical adenosine, inosine, hypoxanthine, and xanthine increased slowly and were significantly elevated after 50 min of hemorrhage. After 80 min, adenosine and inosine had returned to initial levels, while hypoxanthine and xanthine were further elevated. Despite the apparent partial recovery of metabolic disturbances during late hemorrhage, and with a blood flow maintained at 75% of resting control, SEP did not improve. It is suggested that the depression of SEP is not primarily caused by circulatory-metabolic derangements, but instead by activation of specific inhibitory systems.

The aim of this study was to determine the mechanism of action of norepinephrine (NE) on arterial baroreceptors (BRs), with the focus on regularly discharging, presumably myelinated fibers. With the use of an in vitro aortic arch/aortic nerve preparation from rats, BR single-fiber discharge was recorded simultaneously with aortic pressure and diameter. At constant suprathreshold pressure, NE had two dose-dependent effects. Inhibition was produced at low concentrations (10(-10)-10(-7) M), whereas excitation was produced at high concentrations (10(-6)-10(-5) M). Inhibition was attributed to BR unloading since the response was consistent with the fall in diameter, was mimicked by angiotensin II (10(-10)-10(-6) M), and was prevented by pretreatment with the smooth muscle relaxant sodium nitroprusside (10(-6) M) or the selective alpha 1-adrenergic antagonist, prazosin (10(-6) M). Excitation was attributed to direct activation of the BR endings since this response was independent of changes in diameter, was not mimicked by angiotensin II, and was not prevented by sodium nitroprusside but was blocked by prazosin. These results indicate that NE has two modes of action, one mediated by contraction of local vascular smooth muscle and the other due to direct excitation of the nerve endings. It was also found that BR discharge at given diameters decreased more when pressure was lowered (smooth muscle passive) than when the aorta constricted (smooth muscle active). Furthermore, if diameter was held constant during smooth muscle contraction, discharge increased, as opposed to decreasing at constant pressure. These later results suggest that BR responses to vasoactive agents reflect not only changes in wall dimension but perhaps changes in wall tension and/or the coupling relation between BR and smooth muscle structures.

The response of 14 atrial receptors with nonmedullated vagal afferents to changes in atrial pressure was determined in anesthetized thoracotomized cats. Recordings were made from 11 single fibers and three two-fiber filaments. Mean conduction velocity was 0.9 m/sec (range, 0.35 to 2.2 m/sec). During the control period, either no activity was detected or there was a sparse discharge (mean, 1.4 impulses/sec), which occasionally was related to the a or v waves. As atrial pressure was increased by transfusion or by occlusion of the aortic, pulmonary arterial, mitral, and tricuspid orifices, an increased rate of firing occurred, often related to the atrial v wave. The threshold for individual receptors was between 2 and 3 mm Hg (mean pressure) in the right atrium, and 5 and 12 mm Hg in the left atrium. The maximal firing rate was 5-11 impulses/sec for right atrial and 10-20 impulses/sec for left atrial receptors. The receptors were localized by probing the opened heart, and were identified in both atria, in the interatrial septum, and in the atrial-venous junctions. Thus receptors connected to vagal C fibers are present throughout both atria and are activated by moderate changes in pressure.

In 7-week-old male, spontaneously hypertensive rats (SHR) and matched normotensive control rats, Wistar Kyoto Rats (WKY), a bilateral renal denervation was performed. In two additional groups of rats a sham denervation was done (SHRS, WKYS). The animals were then kept in metabolic cages during a 10-day period during which sodium intake, urine volume, urinary sodium excretion, fecal sodium excretion, urinary aldosterone excretion and plasma renin activity were determined. Fractional urinary excretion of sodium was higher in the denervated SHR (p < 0.1) and WKY (p < 0.05) during the first 3 days after denervation, but during the following 3-day periods no difference between denervated and sham-operated groups was noted. The difference in fractional urinary excretion of sodium initially was due to a diminished urinary sodium excretion in the sham-operated groups since both SHRS and WKYS exhibited a significant increase between the first and the last 3-day period. Urine volume increased significantly in both SHR and WKY after denervation. Urinary aldosterone excretion on the 7th day after denervation was significantly lower in SHR compared to WKY, but there was no significant difference between the denervated and sham-operated groups. PRA was also significantly lower in SHR but no significant decrease was seen after denervation.

The study was undertaken to examine if endogenous opioid systems mediate the response of the sympathetic nervous system to halothane anesthesia. Steady state values of renal sympathetic nerve activity (rSNA), mean arterial pressure (MAP), and heart rate (HR) were continuously recorded in the conscious state and at three depths of halothane anesthesia (0.6%, 1.2%, and 2.4%) in rats. Halothane caused an inhibition of rSNA and hypotension and a decrease in HR at the three halothane concentrations. Repeated bolus doses of the opiate antagonist (-)naloxone given iv during 1.2% halothane anesthesia did not significantly increase any of the variables. However, pretreatment with (-)naloxone (2 or 15 mg.kg-1) induced an increase in rSNA at 0.6% halothane, and subsequently the rSNA inhibition was less pronounced at the two higher halothane concentrations compared with control. HR showed a similar pattern, whereas the hypotension was essentially unaffected. Pretreatment with the pharmacologically inactive compound (+)naloxone had no effect on the halothane-induced depression of rSNA. The ED50 halothane concentration concerning nociceptive aversive behavior was not significantly changed with (-)naloxone pretreatment (2 mg.kg-1). In order to determine if sympathoinhibitory bulbospinal serotonin pathways are activated during halothane anesthesia, rSNA, MAP, and HR were recorded in rats pretreated with the serotonin synthesis inhibitor parachlorophenylalanine (PCPA). However, PCPA pretreatment did not affect the rSNA response to halothane compared with control. These findings indicate that the halothane-induced inhibition of rSNA might partially result from a stereospecific activation of opioid receptors, whereas halothane analgesia does not seem to be mediated by opioid mechanisms.

Synthese par reaction de la chloro-4' acetophenone avec la dimethylamine en solution aqueuse

Two antihypertensive lipids can be derived from the renal papilla, the antihypertensive polar (APRL) and the antihypertensive neutral (ANRL) renomedullary lipid. The renal venous effluent of the unclipped kidney contains both ANRL and APRL. This effluent lowers the arterial pressure (AP) of the normal rat when infused i.v. As it lowers the AP the heart rate (HR) and sympathetic nerve activity (SNA) are depressed. ANRL infused i.v. also lowers HR and SNA as it depresses the AP. Conversely, APRL elevates HR and SNA as it lowers the AP. Thus, of the two lipids in the renal venous effluent after unclipping, ANRL appears to be dominant. APRL, however, in the renal venous effluent could potentiate the action of ANRL. The net effect of these observations is to support the view that ANRL is an antihypertensive hormone liberated by the kidney after unclipping. The renomedullary interstitial cells (RIC) degranulate after unclipping. ANRL can be derived from these cells. Thus, the RIC, cells known to exert an endocrine-type antihypertensive function, may well be the source of ANRL in the renal venous effluent after unclipping. The hormonal action of ANRL appears as a major cause of the lowering of the AP after unclipping. It is not known what factors modulate the RIC endocrine system. There is a suggestion that angiotensin may be one of these factors based on the ineffectiveness of these cells toward retarding hypertension when the circulating plasma angiotensin level is high, and their effectiveness when the circulating plasma angiotensin level is low.

CBF and somatosensory evoked potentials (SEPs) were measured in a model of moderate cerebral ischemia in anesthetized spontaneously hypertensive rats. The rats were bled to reduce SEP amplitudes to about 50% of prebleeding control. The consequent blood pressure fall reduced CBF to 77% of control as measured by the laser-Doppler technique. Naloxone (5 mg kg−1 i.v. plus 25 mg kg−1 h−1 i.v. for 30 min) caused a significant increase in SEP amplitudes, while CBF did not change significantly. In addition, the latency of the first SEP component decreased toward prebleeding values. Heart rate (HR) decreased, but MABP was held constant by a pressure-regulating reservoir. In unbled rats, naloxone (5 mg kg−1 i.v.) caused a transient small increase in MABP and SEP amplitudes and decrease in HR. These results indicate that sensory input is regulated by opioid systems. Increased opioid activity may inhibit ascending sensory pathways during relative cerebral ischemia and thereby depress SEP responses. Thus, naloxone can release this inhibition and enhances SEP independently of CBF during relative cerebral ischemia. Similar mechanisms might explain the apparently beneficial effects of naloxone in some stroke models.

Two antihypertensive lipids can be extracted from fresh renal medulla. One is polar (the antihypertensive polar renomedullary lipid, or APRL) and the other is nonpolar (the antihypertensive neutral renomedullary lipid, or ANRL). APRL and ANRL differ in their biologic activities: APRL in bolus intravenous injections causes a very rapid decline in the arterial pressure (AP) while ANRL, after a lag of 2 minutes, causes a slower decline in AP. APRL increases heart rate and sympathetic activity. ANRL decreases heart rate and sympathetic activity. ANRL appears to convert to APRL, under certain in vitro circumstances, suggesting that the structure of the two molecules is related. ANRL and APRL appear in the renal venous effluent after unclipping; biologically, ANRL seems dominant. The renal venous effluent of the unclipped isolated kidney lowers the HR and sympathetic activity of the normal rat. Unclipping degranulates the renomedullary interstitial cells (RIC). The antihypertensive effect of unclipping appears due to the secretion of ANRL and APRL by the kidney. It is concluded that ANRL seems to be the antihypertensive hormone of the RIC.