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The study aims to investigate the relationships between colostral concentrations of insulin-like growth factor 1 (IGF-1), immunoglobulin G (IgG) and vitamin A (Vit A) and growth (body weight and average daily gain) in Black Bengal (BB) and its crossbred. The colostrum from dams (n = 16) was collected at parturition to measure the concentrations of IGF-1, IgG and Vit A. The kid weight at birth (W-0), day 14 (W-14) and day 28 (W-28) were measured and the average daily gain during day 1-14 (ADG1-14) and day 14-28 (ADG14-28) were calculated. The average concentrations of IGF-1, IgG and Vit A in colostrum were 504.6 ± 74.9 ng/ml, 9.7 ± 0.6 mg/ml and 549.1 ± 72.5 µg/100 g, respectively. The average body weight of kids at birth, day 14 and 28 were 1.72 ± 0.08, 2.95 ± 0.11 and 3.94 ± 0.13 kg respectively. Kid's breed, IGF-1, IgG and Vit A had significant positive effects on ADG14-28 while parity, litter size and sex had no effect. The growth factors that were classified into 2 classes based upon the mean values of colostral contents in all kids showed that the kids receiving the higher concentrations of IGF-1, IgG and Vit A in colostrum had higher body weight gain than those receiving the lower concentrations (92.1 ± 7.8 vs. 59.8 ± 5.7 g/day; p = 0.002, 88.3 ± 7.8 vs. 60.3 ± 6.1 g/day; p = 0.009 and 91.1 ± 6.8 vs. 56.7 ± 5.8 g/day; p 0.001 respectively). It is concluded that IGF-1, IgG and Vit A concentrations in colostrum of dams were associated with increased kid's body weight gain at the end of first month in BB and BB crossbred goats.

Background Polymorphisms of the vitamin D receptor (VDR) are associated with calcium oxalate (CaOx) nephrolithiasis in humans. Objectives To investigate the association between VDR polymorphisms and susceptibility to CaOx urolithiasis in dogs. Animals Thirty‐five dogs with CaOx urolithiasis were compared with 40 stone‐free dogs. Methods This was a case‐control study. Two VDR gene polymorphisms (rs851998024 and rs852900542) were detected by specific TaqMan real‐time polymerase chain reaction assay, and their relationship with serum 1,25‐dihydroxyvitamin D, serum and urinary electrolyte concentrations was evaluated. Results The distribution of the rs852900542 polymorphism was significantly different between the case and the control dogs (x 2 = 6.369, P = .04). Dogs with a CC or CT genotype had an increased risk of CaOx stones than those with the TT genotype (odds ratio = 3.82, 95% confidence interval 1.04‐13.98). The CaOx dogs with the TT genotype had a significantly lower urinary calcium‐to‐creatinine ratio than the CT+CC genotypes. 1,25‐(OH)2D concentrations did not differ between the cases and the controls (308.7 ± 217.4 vs 286.7 ± 185.1 pg/mL, P = .45). Conclusions and Clinical Importance This finding suggests that vitamin D metabolism might play a role in CaOx stone formation in dogs.

Iron metabolism, hepcidin and some blood profiles were investigated in 13 healthy and 31 chronic kidney disease (CKD) dogs. The study consisted of 2 experiments, experiment I included healthy dogs (CONT) and CKD dogs (stage 2, 3 and 4), while experiment II consisted of anemic CKD dogs subjected to 28-day darbepoetin alfa treatment. The response to darbepoetin alfa could divide anemic CKD dogs into responder (RP) and non-responder (NRP) subgroups. The results from experiment I showed that packed cell volume (PCV) and plasma albumin concentration were significantly lower in CKD dogs of all stages while the total iron binding capacity (TIBC) was lower in only CKD stage 3 and 4 compared with dogs in CONT group. The PCV was related to both TIBC and albumin when considering among all dogs or only in CKD dogs. The hepcidin concentration in CKD dogs with anemia was lower than those without anemia (P

Chronic kidney disease (CKD) is a common renal disease in dogs and cats. Renal fibrosis is a main pathologic process leading of CKD progression. Renal biopsy is the gold standard for renal fibrosis assessment. However, it is not routinely performed in clinic due to its invasiveness. Therefore, the aim of this study was to evaluate the use of ultrasonographic strain elastography (SE), which is a non-invasive method for renal tissue stiffness determination and its association with renal function. Renal strain ratios and renal function were evaluated in 13 CKD dogs (CKDD), 38 healthy dogs (HD), 17 CKD cats (CKDC) and 26 healthy cats (HC). There were significantly lower renal cortical strain ratios than medullary strain ratios in all groups (HD; P

The objective of the present study was to determine the factors that influenced growth performance of the goat kids of Black Bengal (BB), Saanen (SA), and their crossbred F1 (male Bengal × female Saanen [BBSA] and male Saanen × female Black Bengal [SABB]). Data for 674 kids were analyzed from 316 litters and 134 does. All kids were weekly measured on their characteristics (body weight, length, height at the withers, and chest girth) from birth to 11 weeks old. The kid's breed and sex, litter size, and season of kidding influenced birth weight and other characteristics through the experiment. The SA and BBSA kids showed similar performance, which were higher than BB and SABB kids. Male kids had higher performance than female kids, and kids from a single litter showed the highest performance. Kids born during rainy season showed lower performance than those born in hot and cool seasons. In conclusion, the crossbred BBSA is superior to SABB or BB to raise in tropical climate Moreover, sex, litter size, and kidding season also affected growth performance during the preweaning period up to 11 weeks old.

Sildenafil is a selective phosphodiesterase-5 inhibitor that has been demonstrated to delay ventricular remodeling in humans and experimental animals. The aim of this prospective study was to assess the chronic effects of sildenafil administration on echocardiographic indices and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with naturally occurring, asymptomatic myxomatous mitral valve degeneration. Thirty client-owned dogs with ACVIM class B1 or B2 were enrolled. Dogs were randomly assigned to treatment (sildenafil 1–3 mg/kg, PO, BID for 180 days) or control groups. A total of 12 dogs completed the 180 days trial in the sildenafil group, whereas 10 dogs remained in control group. When comparing the difference from baseline values obtained over time between groups, the stroke volume (SV) at day 30 was significantly higher in the sildenafil group (P=0.038). The LA/Ao and the MR jet area were significantly lower beginning at day 30 (only MR jet area; P=0.006), day 90 (P=0.006 and P=0.027, respectively) and day 180 (P=0.029 and P=0.032, respectively). The 2D-LA was significantly lower at day 90 when compared with control group (P=0.028). The differences of NTproBNP from baseline were significantly lower when compared with control group at the same timepoint (D90, P=0.017 and D180, P=0.013). In conclusion, this study suggested that long-term treatment with sildenafil prevented aggravation of disease progression as suggested by several echocardiographic indices (i.e. SV, LA/Ao, MR jet area, 2D-LA) and reduced NTproBNP level at the indicated timepoints in dogs with asymptomatic mitral valve degeneration.

Klotho protein is recognized as having a renoprotective effect and is used as a biomarker for kidney injury. We investigated the level of Klotho protein in hyperoxaluria-induced kidney injury and the effects of vitamin E (Vit E) and vitamin C (Vit C) supplementation. Hyperoxaluria was induced by feeding 2% (w/v) Hydroxy-L-proline (HLP) in the drinking water for 21 days. Rats were divided into 5 groups; control (Group 1, n=7), HLP treated rats that received nothing else (Group 2, n=7), Vit E (Group 3, n=6), Vit C (Group 4, n=6) and both Vit E and Vit C (Group 5, n=7). Vit E (200 mg/kg) was injected on days 1, 6, 11 and 16, while Vit C (500 mg/kg) was given intravenously on days 1 and 11. The Klotho protein levels and oxidative status were measured. The expression level of kidney Klotho protein expression was significantly reduced by HLP-treatment, while the mRNA expression was higher (P

Hyperoxaluria and oxidative stress are risk factors in calcium oxalate (CaOx) stone formation. Supplement with antioxidant could be effective in prevention of recurrent stone formation. The present study aims to evaluate the protective effects of vitamin E and vitamin C in hyperoxaluric rat. The experiment was performed in rats for 21 days. Rats were divided into 5 groups as follows: control (group 1, n=8), hyperoxaluric rats (group 2, n=8), hyperoxaluric rats with vitamin E supplement (group 3, n=7), hyperoxaluric rats with vitamin C supplement (group 4, n=7) and hyperoxaluric rats with vitamin E and C supplement (group 5, n=7). Hyperoxaluria was induced by feeding hydroxyl L-proline (HLP) 2% w/v dissolved in drinking water. Intraperitoneal 200 mg/kg of vitamin E was given in groups 3 and 5 on days 1, 6, 11 and 16, while 500 mg of vitamin C was injected intravenously in groups 4 and 5 on days 1 and 11. Renal functions and oxidative status were measured. The urinary oxalate excretion was increased in HLP supplement rats, while glomerular filtration rate, proximal water and sodium reabsorption were significantly lower in group 2 compared with a control (P

The role of cardiac autonomic modulation on ventricular arrhythmia, known as ventricular premature complexes (VPC), after splenectomy was investigated. Twelve dogs undergoing splenectomy were divided into 2 groups: low VPC (

Objective: The aim of the present study was to investigate the beneficial effects of dietary supplementation with oil palm frond (leaf) (OPF) with and without oil palm meal (OPM) on nutrient intake and digestibility, ruminal fermentation and growth performance in goats.Methods: Six female crossbred goats were fed for 28 days of 3 diet treatments; 100% paragrass (T1); 50% para-grass + 50% OPF (T2), and 30% para-grass + 50% OPF + 20% OPM (T3). Body weight, rectal temperature, respiratory rate, and urine volume, food intake, dry matter intake and water intake were measured daily. Nutrient digestibility was determined from five consecutive days of last week in each diet. Ruminal fluid, urine and blood were collected at the end for determination of rumen protozoa and volatile fatty acid contents, urinary allantoin excretion, blood cell count and chemistry profiles.Results: Goats fed T2 and T3 showed higher dry matter and nutrients intakes while protein digestibility was suppressed compared with those for T1. Crude fat digestibility declined in T2 but maintained after adding the OPM (T3). High fat intake by giving OPF and OPM corresponded to a higher ruminal acetate/propionate ratio (C2/C3) and serum cholesterol level. An increased urinary allantoin/creatinine ratio was found in T2 and T3 compared with T1, implying an increased number of ruminal microbes.Conclusion: Increased dry matter intake in T2 and T3 suggested that oil palm by-products are partly useful as a replacement for para-grass in goats. Replacement with the by-products increased plasma cholesterol level, which suggested that these products are a useful energy source. Changes in rumen parameters suggested an increased microbial number and activity suitable for acetate production. However, the limited digestibility of protein implies that addition of high protein feeds may be recommended to increase body weight gain of goats.

Dronedarone is a class III antiarrhythmic that has been used for management of atrial fibrillation in humans, but limited information was found in dogs. The objective of this study was to determine the acute effects of escalating concentrations of dronedarone on electrocardiograms (ECG), hemodynamics and cardiac mechanics in healthy dogs. A total of 7 beagle dogs were anesthetized with isoflurane and instrumented to obtain lead II ECG, pressures at ascending aorta, right atrium, pulmonary artery and left ventricle, and left ventricular pressure-volume relationship. Five dogs were given vehicle and followed by escalating doses of dronedarone (0.5, 1.0 and 2.5 mg/kg, 15 min for each dose), and two dogs were used as a vehicle-treated control. All parameters were measured at 15 min after the end of each dose. The results showed that all parameters in vehicle-treated dogs were unaltered. Dronedarone at 2.5 mg/kg significantly lengthened PQ interval (P

The evaluation of proarrhythmic and hemodynamic liabilities for new compounds remains a major concern of preclinical safety assessment paradigms. Contrastingly, albeit functional liabilities can also translate to clinical morbidity and mortality, lesser preclinical efforts are focused on the evaluation of drug-induced changes in inotrope and lusitrope, particularly in the setting of concomitant hemodynamic/arrhythmic liabilities. This study aimed to establish the feasibility of an anesthetized guinea pig preparation to assess functional liabilities in the setting of simultaneous drug-induced electrocardiographic/hemodynamic changes, by evaluating the effects of various compounds with known cardiovascular properties on direct and indirect indices of left ventricular function. In short, twenty nine male guinea pigs were instrumented to measure electrocardiograms, systemic arterial pressure, and left ventricular pressure-volume relationships. After baseline measurement, all animals were given intravenous infusions of vehicle and two escalating concentrations of either chromanol 293B (n = 8), milrinone (n = 6), metoprolol (n = 7), or nicorandil (n = 8) for 10 minutes each. In all cases, these compounds produced the expected changes. The slope of preload-recruitable stroke work (PRSW), a pressure-volume derived load independent index, was the most sensitive marker of drug-induced changes in inotropy. Among the indirect functional indices studied, only the "contractility index" (dP/dtmax normalized by the pressure at its occurrence) and the static myocardial compliance (ratio of end diastolic volume and pressure) appeared to be adequate predictors of drug-induced changes in inotropy/lusitropy. Overall, the data confirms that both electrophysiological and mechanical liabilities can be accurately assessed in an anesthetized guinea pig preparation.

Oxidative stress parameters and erythrocyte characteristics were studied in 15 normal healthy dogs and 33 renal azotaemic dogs from Small Animal Hospital, Faculty of Veterinary Science, Chulalongkorn University. Dogs with renal azotaemia had reduced mean corpuscular volume (MCV) (P

Oxidative stress parameters; thiobarbituric acid reaction substances (RBC-TBARS), catalase (RBC-CAT) and reduced glutathione (RBC-GSH)) and the intraerythrocytic concentrations of electrolytes; sodium and potassium (RBC-Na and RBC-K) were determined in 18 well- controlled (WC) and 22 poorly-controlled diabetic mellitus (DM). Dogs with DM had significant higher blood glucose concentration (P

Blood pressure (BP) was measured in 31 renal azotaemic dogs by oscillometric measurement at the posterior tibia artery, and urine and blood samples were collected. Haematology, blood chemistry and urinalysis were performed and urinary protein:creatinine ratio (UPC) and fractional excretions of electrolytes (FE(e)) were calculated. The results showed that only 19% of dogs with renal azotaemia were hypertensive, whereas almost all of them had high urinary protein and electrolyte excretions. There was no association between BP, UPC and FE(e). A positive correlation was found between all pairs of electrolyte fractional excretions. When the severity of renal impairment was observed using plasma creatinine concentration, neither BP nor UPC was correlated. Only the FE( e ) was associated with the degree of azotaemia. The results suggest that dogs with renal azotaemia do not necessarily have hypertension. The fractional urinary excretion of electrolytes may be a good indicator for severity of renal dysfunction in azotaemic dogs.

SUMMARY: Aim: Effects of L-carnitine on nephrotoxicity and oxidative stress induced by doxorubicin (DOX) in rats were investigated. Methods: The rats were divided into four groups: group 1, control (0.9% NaCl); group 2, DOX injection (7.5 mg/kg, i.v.); group 3, DOX plus low dose (40 mg/kg) L-carnitine; and group 4, DOX plus high dose (200 mg/kg) L-carnitine. L-carnitine was administered 1 h before doxorubicin injection and daily thereafter for 15 days. Results: Rats in group 2 were associated with hypoalbuminaemia, hyperlipidaemia, high urinary excretion of protein and elevated plasma creatinine and urea nitrogen. The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) decreased with increased renal vascular resistance (RVR). Kidney catalase (CAT) activity was decreased. In group 3 and 4, plasma triglyceride and cholesterol declined. L-carnitine improved renal functions by elevated GFR and ERPF and decreased plasma creatinine and urea nitrogen. The kidney CAT activity were increased significantly compared with group 2. From histopathological results, group 2 rats were found to have glomerular capillary dilation and tubular dilation. The lesions were less in group 3 and 4 rats. Conclusion: L-carnitine can protect renal impairment functionally, biochemically and histopathologically with a corresponding reduction of oxidative stress.

Objective—To determine effects of variations in dietary intake of sodium chloride (NaCl) on systemic arterial blood pressure (ABP) in cats with normal and reduced renal function. Animals—21 adult cats (7 with intact kidneys [control cats; group C], 7 with unilateral renal infarction with contralateral nephrectomy [remnant-kidney model; group RK], and 7 with unilateral renal infarction and contralateral renal wrapping and concurrent oral administration of amlodipine [remnant-wrap model; group WA]). Procedure—All cats were sequentially fed 3 diets that differed only in NaCl content (50, 100, or 200 mg of Na/kg); each diet was fed for 7 days. The ABP was recorded continuously by radiotelemetry, and renal function (glomerular filtration rate [GFR]) was determined on the sixth day of each feeding period. Results—Dietary supplementation with NaCl did not affect ABP, but it increased GFR in groups C and WA. The renin-angiotensin-aldosterone axis was activated in groups RK and WA at the lowest NaCl intake, but supplementation with NaCl suppressed this activation in group WA. The lowest NaCl intake was associated with hypokalemia and a high fractional excretion of potassium that decreased in response to supplementation with NaCl. Arterial baroreceptor resetting was evident after chronic hypertension but was not modified by dietary supplementation with NaCl. Conclusions and Clinical Relevance—Low NaCl intake was associated with inappropriate kaliuresis, reduced GFR, and activation of the renin-angiotensinaldosterone axis without evidence of a beneficial effect on ABP. Therefore, this common dietary maneuver could contribute to hypokalemic nephropathy and progressive renal injury in cats. ( Am J Vet Res 2004;65:620–627)

There is evidence to suggest that antiplatelet aggregation and inhibition of angiotensin converting enzyme will attenuate the progression of renal disease. In the present study, dipyridamole (DPM; 30 mg/kg per day, p.o.) or fosinopril (FOS; 20 mg/kg per day, p.o.) was given to rats for 5 weeks starting immediately after renal mass reduction (right uninephrectomy and ligation of approximately two-thirds of the blood supply to the left kidney). Renal mass reduction caused increased mean arterial blood pressure, reduced effective renal plasma flow (ERPF) and glomerular filtration rate (GFR), azotemia and proteinuria. Neither proteinuria nor hypertension was affected by DPM, although renal function improved markedly. Rats receiving FOS showed normalization of blood pressure with a significant increase in both ERPF and GFR, along with a lower degree of proteinuria. A histological examination of the remnant kidney detected the presence of vasodilation with a lower degree of podocyte swelling in both treatment groups, with a remarkable effect in the FOS group. These data indicate that both FOS and DPM attenuate the progression of glomerular disease associated with renal mass reduction in rats. However, FOS was more beneficial than DPM because it reduced proteinuria and lowered blood pressure.

The blood pressure, renal function, baroreflex response of heart rate and noradrenaline (norepinephrine) pressor response were determined in conscious, normotensive, sodium-replete dogs that had received fosinopril. Oral administration of fosinopril at a dose of 1 mg/kg per day for 5 days decreased the systolic arterial pressure from 147.1±3 to 131.8±4.3 mmHg (p

Heart rate variability (HRV) and echocardiography were performed in 14 dogs with mitral regurgitation (MR) before and after 14 days of 0.5mg/kg/day of enalapril treatment. All dogs were in heart failure stages B1 and B2. After enalapril treatment, left ventricular end diastolic diameter (LVEDd), left ventricular end diastolic diameter normalized for body weight (LVEDdN) and percent mitral regurgitant jet decreased (P0.05). The diastolic blood pressure decreased (P0.05). Increased time domain parameters of HRV were found. For frequency domain analysis, the total frequency (TF) increased significantly (P0.05). The normalized low frequency (LF norm) decreased while normalized high frequency (HF norm) increased causing significant reduction in LF/HF (P0.05). Before enalapril treatment, LF was correlated with end diastolic volume (EDV) (P0.01) and LVEDd (P0.05). In conclusion, MR dogs receiving enalapril treatment for 14 days had increased cardiac parasympathetic tone while sympathetic tone was suppressed. The decreased sympathetic activity corresponded to the reduction in cardiac preload and afterload.

Cardiac autonomic neuropathy in dogs with diabetic mellitus (DM) was evaluated using measurement of heart rate variability (HRV) and plasma norepinephrine (NE) concentration. Dogs were divided into 2 groups; the control non-DM group (n = 13) and the diabetic group (n = 22) which was further divided into the well-controlled DM (n = 11) and the poorly-controlled DM subgroups (n = 11) according to their fasting plasma fructosamine concentrations. The electrocardiogram (ECG) was recorded continuously for at least 30 min to yield HRV. The results showed that in the poorly-controlled DM subgroup, the average of normal R-R interval (mean N-N), SD of the mean of all 5-min segments of normal RR intervals (SDANN) were lower than the control group while heart rate was higher (P < 0.05). The NNA, SDNN, SDNN index and pNN50% were significantly lower when compared with the well-controlled DM subgroup (P < 0.05). The high frequency (HF) and total power were significantly lower while the ratio of low to high frequency (LF/HF) was higher (P < 0.05) when compared with the well-controlled DM subgroup. Moreover, in the poorly-controlled DM subgroup, plasma NE concentration was lower than the control group (210 ± 37 vs. 479 ± 74 pg/ml, P < 0.05). There was a significantly negative correlation between plasma NE and plasma fructosamine concentrations. It is concluded that cardiac autonomic neuropathy occurred in poorly-controlled DM dogs. The sympathetic activity was suppressed as shown by decrease in both plasma NE concentration and LF component.

The effects of brimonidine, an alpha(2)-adrenoceptor agonist, on blood pressure, heart rate, respiratory rate, renal function and some blood parameters were investigated in 10 dogs. Dogs were divided into two groups, low dose (LD; 0.2 mg/kg) and high dose (HD; 0.5 mg/kg) of brimonidine given orally. The alpha(2)-adrenergic antagonist yohimbine hydrochloride was injected to dogs at a dose of 0.1 mg/kg in both groups at the fifth hour after brimonidine administration. The results demonstrated that after administration of brimonidine, mean arterial blood pressure decreased dramatically at 2 h by 23% and 20% in LD and HD groups, respectively. Heart rate was decreased in a similar manner and both remained low at 5 h after brimonidine administration. Respiratory rate was decreased by 50%, while the electrocardiogram showed prolongation of the PR interval. Glomerular filtration rate (GFR) and effective renal blood flow were reduced when measured at 4 h after brimonidine ingestion in both groups, but the effect was more pronounced in the LD group. Brimonidine caused natriuresis and kaliuresis in both LD and HD groups. The packed cell volume was decreased and hyperglycaemia was detected. Most of the effects can be reversed completely after administration of yohimbine. However, yohimbine can restore GFR only partially. These data suggest that brimonidine caused cardiovascular and respiratory depression. The adverse effects of this drug can be antagonized by yohimbine, suggesting that these effects were mediated via the alpha(2)-adrenoceptor.

We studied whether the effects of bethanechol are mediated via a muscarinic receptor, the role of extracellular calcium on bladder contraction, and down-regulation of bladder contraction by bethanechol after activation with potassium chloride (KCl) and acetylcholine (Ach). Smooth muscle strips of normal urinary bladder were studied with standard methods to measure isometric force. Bethanechol caused a dose-dependent increase in bladder contraction. The potency of bethanechol is higher than Ach, as shown by higher peak active isometric stress (P(max)) and lower half-maximal contraction (ED(50)) (P< 0.01). The contractile responses to bethanechol were diminished in the presence of atropine, nifedipine and in calcium-free medium as shown by P(max) decreased by 58%, 87% and 65% and ED(50) increased by 314-, 24- and 16-fold, respectively. When bladder strips were stimulated with KCl and Ach, pre-treatment with bethanechol reduced the responses to KCl by 116-242% (P

Objective—To determine norepinephrine (NE) kinetics in dogs with experimentally induced renal vascular hypertension. Animals—4 mixed-breed dogs. Procedure—The study comprised a control and hypertensive period. The hypertensive period followed induction of renal vascular hypertension achieved by surgical placement of clips on both renal arteries to reduce diameter by approximately 80%. Arterial blood pressure, renal clearance, and NE kinetics were measured during each period while dogs were receiving a low-sodium diet. Measurements of NE kinetics and renal clearance during the hypertensive period were made 5 days after induction of hypertension. Results—Five days after induction of hypertension, arterial blood pressure increased by 15 to 20 mm Hg. Mean (± SEM) plasma NE concentration and NE spillover rate increased significantly from 151.5 ± 14.1 pg/ml and 8.03 ± 0.62 ng/kg/min, respectively, during the control period to 631.4 ± 30.5 pg/ml and 54.0 ± 5.2 ng/kg/min, respectively, during the hypertensive period. Norepinephrine clearance rate also increased (54.0 ± 2.4 vs 86.0 ± 9.3 ml/kg/min). Positive associations between mean arterial pressure (MAP) and NE concentration and spillover rate were detected. However, MAP and NE clearance rate were not associated. Conclusions and Clinical Relevance—Increased blood pressure during the hypertensive period was likely attributable to increased NE spillover rate, which resulted in a significant increase in plasma NE concentration. Analysis of these results suggests that central sympathetic outflow was increased and may be responsible for the pathogenesis of high blood pressure during the acute phase of renal vascular hypertension in dogs. (Am J Vet Res 2000;61: 1534–1541)

During 2 h of acute heat exposure in pigs (36:27 °C, dry bulb: wet bulb temperature), the rectal temperature increased from 40·5 to 42·3 °C, the heart rate (HR) increased from 122 ± 7 to 176 ± 16 beats/min, and the respiratory rate (RR) increased from 48 ± 9 to 196 ± 11 breaths/min. There were no significant changes in the mean arterial blood pressure and renal haemodynamics in heat-stressed pigs. Plasma concentration of Cl− significantly increased while plasma Na+ and K+ did not change. In the second hour of heat exposure, the rate of urine flow was unchanged while urinary pH and fractional and urinary excretion of K+ significantly increased. The intravenous injection of β-blocker carazolol (0·1 mg/kg) in heat-stressed animals slightly affected RR, while there was a marked reduction of HR. The glomerular filtration rate and renal blood flow slightly increased whereas fractional excretion of K+, plasma Cl− concentrations, and urinary pH markedly decreased after carazolol administration. These findings suggest that in heat-stressed animals, carazolol influences the renal electrolyte transport activities by directly altering the acid-base balance mechanism.