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The objectives of this study were to: (a) test the functional activity of Chinchilla lanigera spermatozoa suspended in either glycerol or ethylene glycol, cooled to 4 degrees C, and stored for 24 or 72 h and (b) investigate, after these cooling periods, the effects of incubating sperm at 37 degrees C (for 4 h) upon sperm functional activity. The ejaculate was mixed with the cryoprotectant medium (at 1 M final concentration) and cooled to 4 degrees C. After warming, sperm motility, sperm viability, hypoosmotic swelling test results, and acrosomal integrity were significantly higher for samples containing ethylene glycol than for those in glycerol, stored for 24 or 72 h, and then assayed after 0 or 4 h incubation at 37 degrees C. A significant reduction of sperm motility and viability was detected only when the glycerol cryoprotectant agent was employed, compared to the fresh samples. These results clearly indicate that under our experimental conditions, ethylene glycol is a better protectant for sperm storage than glycerol., (Copyright 2001 Elsevier Science.)

To investigate some possible effects of low doses of nonsteroidal anti-inflammatory drugs upon functional activity of mouse sperm, the authors injected lysine acetyl salicylate (im 14.3 mg/kg day(-1), ibuprofen (ip 5.6 mg/kg day(-1)), or piroxicam (ip 0.28 mg/kg day(-1) to pregnant females (the male cohort was sacrificed at adulthood) (A) or to adult males during 35 (B) or 60 (C) days. Parameters measured were motility, viability, acrosomal integrity, responses to hypoosmotic shock, in vitro fertilization index, and testosterone plasma levels. Salicylate evoked a slight reduction in the percentage of swollen gametes in A, and ibuprofen diminished testosterone plasma levels in B. The other parameters remained unchanged in all groups. Results are well supported by the low doses assayed, which are equivalent to the content of one tablet commercially available for each compound.

Although the in vitro fertilisation index is a parameter commonly employed to investigate sperm functional activity, little attention has been given to the occurrence of parthenogenesis. The purpose of this study was to study at 6 h or 22 h incubation: (a) the cleavage-related events that occur in in vitro incubated mouse oocytes, in the absence (parthenogenesis) or presence of homologous spermatozoa; (b) the effect of mineral oil, commonly used in in vitro fertilisation assays; (c) the effect of piroxicam, a prostaglandin synthesis inhibitor, on the parthenogenetic rate; and (d) the influence on parthenogenesis of spontaneous loss of the cumulus oophorus coat during incubation. Under the experimental conditions employed, there was parthenogenetic activation and activation due to fertilisation. Both increased in a time-dependent manner. The mineral oil enhanced the parthenogenetic rate at 22 h incubation. However, it did not have any effect when the oocytes were inseminated. Since we can not discriminate how much of this activation was due to fertilisation and how much to parthenogenesis we must be very careful with this comparison. Piroxicam 10(-8) M did not show any effect on the mouse oocyte parthenogenetic rate at neither 6 h or 22 h incubation. Our results suggest that oocyte susceptibility to spontaneous parthenogenetic activation may be modified by the presence of the cumulus and corona radiata cells. In conclusion, we consider that further rigorous studies on these influences are necessary in order to confer more reliability on the results.

In epididymal mouse spermatozoa, the effects of dibutyryl cyclic adenosine monophosphate 1 mmol/L (dbcAMP), pentoxifylline 5 mmol/L (PX), and/or mastoparan 50 mumol/L (MT) were evaluated for the following parameters: percentage of motile cells and response to hypoosmotic shock (HOS). The gametes were incubated during 80 min (A) or 200 min (B) in Tyrode's medium, and the drugs were added during the last 20 min. In A, dbcAMP + PX (61.5 +/- 5.4%; n = 10) enhanced and MT decreased significantly the population of motile cells (13.4 +/- 5.4%; n = 6) (control: 47.6 +/- 3.9%; n = 11). In B, PX significantly increased this parameter and MT plus PX also exerted a significant detrimental effect. Responses to HOS dropped significantly in the presence of PX + MT in A or in B; in this latter condition a similar decrease was evoked by MT alone. A positive correlation between percentages of swollen and motile spermatozoa was detected in A or in B in samples incubated with PX (r = .58, n = 11 and r = .76, n = 10; p < .05, respectively). These results that support that, in mouse sperm tail, PX would preserve functional membrane integrity, a relevant condition for adequate motility.

Because reproductive studies and the application of assisted reproductive techniques are relevant issues for an endangered species such as Chinchila laniger, the availability of a source of viable spermatozoa becomes of utmost importance. In this paper, we evaluate several functional parameters (motility, viability, response to hypoosmotic swelling test and acrosomal integrity) of fresh or frozen-thawed spermatozoa. Electro-ejaculation trials (50-cyc/sec sinusoidal wave was applied for 5 of every 10 sec) were successful in all unanesthetized animals. After volume (108.3 +/- 12.0 microL, n = 15) and concentration (421.8 +/- 34.4 x 10(6) cells/mL, n = 15) measurements, the above mentioned parameters were determined. In frozen-thawed semen samples sperm motility, viability, hypoosmotic swelling test and acrosomal integrity were significantly lower than in fresh semen samples. The results clearly indicated that electro-ejaculation is a useful method for evaluating spermatozoa for genetic analysis or for used in Al in this species. In addition, the cryopreservation procedure in this study preserved adequate levels of functional sperm activity.

Chinchilla laniger is an endangered species and improved cryopreservation of spermatozoa would constitute a significant advance in the development of assisted reproductive techniques in this species. The functional activity of epididymal spermatozoa from adult males was studied immediately after extrusion and after 24 hours incubation, and the ability of five extenders to protect these gametes during cryopreservation was determined. A decrease in sperm motility, viability, acrosome intact cells and response to hypo-osmotic swelling test was detected 24 hours later. The extenders here assayed showed well-defined differences in their cryoprotective ability; however such differences could not be attributed to any one of their individual components. The presence of TES plus Tris, the proportion of the individual constituents and/or the differences in metabolic substrate content could explain the above-mentioned finding. The results indicate that cryo-buffer II (TES-Tris-egg yolk-fructose-glycerol) is the most powerful protector of sperm functional activity in this species.

Several studies indicate that reactive oxygen species (ROS) are involved in defective sperm function pathophysiology. In this study we attempted to determine differentially the effects of xanthine (0.12 mM) plus xanthine oxidase (0.035 U/mL) (X+XO, a ROS promoter system), ROS scavengers (Tiron (TIR, 15 mM); catalase (CAT, 10 micrograms/mL); dimethylsulfoxide (DMSO, 140 mM)), and X+XO plus scavengers on several epididymal mouse spermatozoa functional parameters, incubated in NTPC medium, for 29 min. In the presence of X+XO, progressive gametes significantly diminished. TIR or CAT attenuated this effect, but DMSO did not. Inversely, X+XO increased the bending-forms population; only TIR reversed this phenomenon. The ROS promoter system diminished the viable cell population; all scavengers assayed maintained sperm viability at levels similar to control ones. When exposed to hypoosmotic shock after 29 min incubation with X+XO, the percentage of swollen cells decreased; TIR, CAT, or DMSO did not prevent this effect. Our experiments demonstrate that it is possible to differentiate the deleterious ROS effects upon sperm functional activity. O-2. and H2O2 preferentially seem to modify sperm motility, O-2. exhibiting the greatest ability for generating bending-form gametes, OH-being the most lethal ROS. In addition, sperm membrane clearly appears as the most damaged structure.

Promethazine is currently used for its antipsychotic and ansiolytic effects. It is a phenothiazine with anticalmodulin action, not toxic for human beings at therapeutic doses. The present results show that promethazine has trypanocidal effect on both epimastigote and trypomastigote stages of T. cruzi; two hundred microM inhibited epimastigote growth in culture medium and 2 microM immobilized and killed bloodstream trypomastigotes. When promethazine (55 mg/Kg/day) was used as treatment of T. cruzi infected mice, it proved effective in reducing parasitemia and it increased the survival of treated animals. Ultrastructural studies suggest that the lethal effect of this phenothiazine is related to a detergent effect that disrupts T. cruzi cell membrane.

The kinetics of functional modifications during in vivo or in vitro incubation was studied in spermatozoa from Albino Swiss mice, obtained from cauda epididymis (E) or from uterus (U) or oviduct (O) post copulation (p.c.). Results clearly suggest that functional activity as reflected by measurements of motility, hypoosmotic swelling test and acrosome reaction differs according to the segments of the reproductive tract from which they were collected. The comparison of results obtained after equivalent periods of in vitro or in vivo incubation, shows that the time course of changes in sperm motility and percentage of swollen sperm is similar in both conditions. Since the percentage of acrosome-reacted gametes was higher in O, at all times scored, oviductal environment appeared to be capable of inducing this phenomenon. Our experimental conditions seemed to be adequate for completion of spermatozoa maturation and successful interaction between male and female gametes as reflected by the results of fertilization rate and embryo cleavage.

The evaluation of spermatic morphology is of importance due to its prognostic value in potential male fertility, both in natural and in assisted reproduction. In the present work, the morphologic profile of samples of semen from normal and dispermic patients was determined, in order to establish a correlation between structure and function. Samples were obtained from male partners of infertile couples who attended andrologic consultation. The smears were stained by the Papanicolaou technique, and the criteria of the OMS and the recent modification of Kruger were followed to evaluate spermatic morphology. Of all the patients studied (n = 46), 35% were normospermics (A), 39% asthenospermics, 7% oligospermics, 2% terastospermics and 17% presented combined alterations. The average percentage of normal spermatozoa was of 23.7 +/- 1.23 in the whole population. When group A patients were compared with asthenospermics, significant differences were found in the percentage of spermatozoa with middle piece and tail alterations, in the last group (p < 0.02). Similarly, when samples were analysed according to the presence of alterations: none (A), one (B) two or more (C), it was observed that the percentage of normal forms decreased in the groups in that order (A < B < C); (A or B vs C p < 0.05). The percentage of tapering spermatozoa was significantly higher in group C (p < 0.01 vs A or B). From the above results, it appears that 1) the larger number of functional alterations is related to a higher percentage of structural anomalies, and 2) the deficient motility in the asthenospermic group, is associated to the middle piece and tail alterations.(ABSTRACT TRUNCATED AT 250 WORDS)

In a preceding paper we reported the evolution of chagasic cardiopathy in mice inoculated with low number of T. cruzi from 2 days to 75 days post-infection (p.i.). The present work analyzed the contractility, pharmacological response and histopathology of myocardium isolated from chronic chagasic mice from 90 days until 180 days. p.i. Myocardium contractile force reached values similar to controls until 165 days p.i. From this to the end contractility was significantly lower. At 90 days p.i. NE provoked negative inotropic effect or had no effect in 13% of the cases tested. The others had a reactivity to NE similar to normal ventricles. From 105 days until 180 days p.i. NE induced to a positive inotropic effect significantly lower than in normal. ACh effect was significantly smaller from 165 days to the end. Previously ACh ventricles responses were as control. The effects of dibenamine, propranolol and atropine (10-6M) on chagasic ventricles were similar to those observed in normal tissues. At 90 days p.i. the histopathology showed focalized inflammatory infiltrates. At 180 days p.i. fibers fragmentations and loss of typical striated characteristic of cardiac tissue. The abnormal pharmacological response described could be attributed to alterations in cardiac beta and muscarinic receptors probably due to a lower oxygen support. The present paper shows that during chronic Chagas' disease myocardial function and pharmacological reactivity are seriously and definitively compromised.

The tricyclic anti-calmodulin drug trifluoperazine (TFP) inhibited growth and motility of epimastigotes of Trypanosoma cruzi, at concentrations lower than 100 microM, and motility and infectivity of the bloodstream trypomastigote form at 200 microM. Electron microscopy of TFP-treated epimastigotes showed that the major effect was at the mitochondrial level, with gross swelling and disorganization. The oligomycin-sensitive, mitochondrial ATPase was completely inhibited by 20 microM TFP, and the same drug concentration caused a 60% decrease in intracellular ATP content. The results suggest that the trypanocidal effect of TFP may be related more to mitochondrial damage than to the well-known anticalmodulin effect of the drug.

Cardiac disease is usually the most serious complication of human infection with Trypanosoma cruzi in our country. This report studies the evolution of the chagasic cardiopathy in mice inoculated with low number of parasites during acute and indeterminate stages in different aspects: contractility, histopathology and pharmacological response. From 2-45 days post infection (p.i.) (acute stage) myocardium contractile force reached higher values than in controls, but norepinephrine (NE) response was significantly lower. Acetylcholine (ACh) caused a negative inotropic effect similar to the observed in control group. In this period cardiac damage evolved to an acute interstitial myocarditis. In the indeterminate phase (45-75 days p.i.) of this parasitosis NE produced either small inotropic effect, negative inotropic effect or had no effect on the ventricles tested. A significantly low ACh effect, sub-endocardiac perivascular fibrosis and necrosis in wall bases were also observed. The abnormal pharmacological response described could be ascribed to modifications in cardiac beta and muscarinic receptors number or affinity. The present results showed that in myocardium isolated from T. cruzi infected mice the histopathology, contractility and pharmacological response were altered from 48 h p.i. reaching a maximum disorder at 60 days p.i.

The scope of this study was to investigate possible relationships between He-Neon laser radiation and mitotic and phase indices in meristematic cells of Allium cepa L. bulbs. Our results indicate that mitotic index increased after irradiation depending this modification on the time exposure and the potency of the He-Neon beam. Phase indices were also modified: frequency of prophase increased, while inter- meta- and anaphase decreased: telophases remain unchanged. These variations were significative only when the preparations were irradiated a) with 5 mW for 10 min. or more, b) with 10 mW or c) when the preparations were processed 60 min. after irradiation. These findings could not be attributed to thermal changes. Modifications in RNA or protein synthesis could be responsible.

The contractile recoverability of isolated portal veins made hypodynamic by removal of glucose from the perfusion medium by diverse exogenous substrates was studied. It was found that glucose, mannose, pyruvate, lactate, acetate, and butyrate readily restored contraction. The effects of anoxia and metabolic inhibitors were also investigated. Both anoxia and dinitrophenol abolished spontaneous activity within 10 min. Fluoroacetate markedly depressed contractility (-60.9 +/- 2.8% at 10 min), the reduction being essentially similar in medium with or without glucose. 2-Deoxy-D-glucose (2-DG) in glucose medium reduced contractility only slightly whereas in the absence of glucose it drastically inhibited contraction (-76% at 10 min and -97% at 40 min). Intracellular ATP was significantly reduced by anoxia and fluoroacetate in medium with or without glucose and by 2-DG only in substrate-free medium. However, ATP depletion showed no clear correlation with the extent of contractile depression. These findings indicate a strong dependence for mechanical activity in this vein on aerobic metabolic pathways. But, from the results with 2-DG, it is suggested that an adequate glucose metabolism might be of importance for functional processes other than contraction itself.

The levels of isometric developed tension (IDT) in portal veins from starved and diabetic rats in glucose medium were of the same magnitude but significantly reduced compared with veins from normal rats. Glucose removal led to contractile depression, more marked in starved veins (-74%; p < 0.001 vs. diabetics and normals). Addition of glucose, pyruvate, acetate, lactate, or butyrate counteracted this depression in all groups but in diabetics butyrate significantly stimulated IDT over controls whereas in starved veins lactate overcame IDT reduction only partially. Added insulin significantly enhanced contractile recovery with glucose in normal and diabetic preparations but was ineffective in starved veins. Glycogen content was significantly lower in diabetics; however, in no group did changes occur in incubated veins as compared with unincubated ones. Glycerol production was significantly higher in diabetic veins. It would appear that, although experimental diabetes induces a shift to fatty acid utilization, aerobic glycolysis and mitochondrial respiration are somehow preserved as reflected by the IDT recovery with pyruvate or lactate.

The presence of prostaglandins (PGs) E1 and F2 alpha in extracts of endometrial, myometrial and placental samples from 19 pregnant women at term, was investigated. The tissue samples were obtained from the following group of patients: untreated, A) with onset of labor, B) without onset of labor; pre-treated (without onset of labor); C) with betamethasone, D) with estradiol-17 beta. Thin-layer chromatography determinations demonstrated PGE1 presence in all tissue samples from the four groups. On the other hand, PGF2 alpha was consistently found in placenta and endometrial samples from groups A, C, and D, but it was absent in those from group B. The results suggest a physiological role of PGF2 alpha in human parturition, and a possible influence of estrogens and corticosteroids on the appearance of this prostaglandin.

In order to display some electrophysiological properties of the motoneurons, a special program for a microcomputer has been designed. The images in the monitor resemble those of an oscilloscope screen. The microelectrode penetration in the cell membrane, magnitude of the resting potential, inhibition and facilitation phenomena and the time-course of a spike potential are shown. The sequences of program's sentences (detailed in the text) can be exhibited in the screen also. Related theoretical basis of neurophysiology and a discussion of the present work are included.

The isometric developed tension (IDT) and the pharmacological response of isolated myocardium from T. cruzi infected Albino Swiss mice in the acute and chronic Chagas' disease, were studied. The animals were infected with 7 X 10(4) trypomastigotes, form of T. cruzi, Tulahuen strain for the acute infection and with 45 parasites for the chronic stage. The isolated myocardium from acute and chronic chagasic mice reached IDT levels similar to normal hearts. The addition of norepinephrine (NE) to acute ventricles led to lower IDT values than in control group; this hyporeactivity to NE was absent in the chronic stage. On the other hand, epinephrine (EPI) effects on acute and chronic ventricles lead to significantly higher IDT values when compared with their controls. Propranolol blocked the higher effect of EPI in isolated myocardium from the acute stage, but the hyperreactivity described in the chronic stage could not be inhibited by the beta receptors antagonist. The agonist and antagonist tested act on cardiac plasma membrane beta receptors and their actions modify transmembrane calcium fluxes, so that the present study shows that Chagas' disease modifies the normal behavior of adrenergic beta cardiac receptors in different degree depending on the stage of the trypanosomiasis.

Oxygen uptake and isometric developed tension (IDT) of isolated rat portal vein were simultaneously measured after glucose removal, following the readmission of metabolic substrates and addition of 2-deoxy-D-glucose (2-DG) or insulin. In control conditions, basal O2 uptake was 0.128 +/- 0.004 microliter O2/mg dry weight/min (n = 50). After 40 min of incubation in a glucose-free medium, IDT and O2 uptake decayed to a similar degree. Addition of 11 mM glucose, 5 mM pyruvate, acetate, lactate or butyrate to hypodynamic veins, elicited differential recoveries in the mechanical and metabolic parameters, pyruvate and acetate being the most effective. Insulin (0.1 U/ml) added 5 min prior to readmission of 11 mM glucose, increased the restoration of IDT without any effect on oxygen uptake. 2-DG 5.5 mM, when added in glucose-free medium, abolished IDT but only depressed the cellular respiration by 38% at 20 min; these effects were decreased in presence of glucose (11 mM). These results suggest that the oxygen uptake of this vessel depends, among other factors, on the exogenous substrate offered. They show also the relationship between peak of developed isometric force and metabolic activity as well as the relevance of glycolytic and oxidative pathways in this tissue.

The effects of piretanide upon mechanical activity and pharmacological reactivity of vascular and myocardial tissues from normotensive rats were investigated. Magnitude of phasic contractions of isolated rat portal vein was diminished by the drug in a dose-related manner; contractile depression induced by piretanide (10(-4)M) was less in the presence of insulin (0.1 U/mL), glucose (22 mM) or pyruvate (5 mM). Responses to KCl (90 mM), or norepinephrine (2.5 X 10(-5)M) were also reduced. Contractile activity of atria and ventricle strips was diminished only when piretanide reached 10(-4)M. Results support direct actions of piretanide upon cardiac and vascular tissues. Possible mechanisms of action are discussed.

The studies concerned the effects of epinephrine, norepinephrine, phenylephrine, acetylcholine and K+ ions, in doses inducing maximal contraction on oxygen consumption of isolated rat portal veins. All the agonists tested stimulated the rate of O2 uptake, whereas high K+ did not. After specific blockade of alpha-adrenoceptors, the effects of epinephrine and norepinephrine on O2 consumption were not affected, whilst those of phenylephrine were abolished, and beta-adrenoceptor blockade suppressed the metabolic effect of epinephrine and norepinephrine. Acetylcholine was the agonist that most elevated O2 consumption; atropine blocked both contractile and metabolic effects of this drug. It appears that there is a clear dissociation between contractile and metabolic actions of some pharmacological agents, and a question is posed concerning phenylephrine and acetylcholine effects. Results with K+ suggest that different metabolic pathways might be involved in the activation and maintenance of drug-induced contraction in smooth muscle.

The present study investigates the effects of Sodium Nitroprusside (SNP) on isometric developed tension (IDT) and tonic component of K+ induced contracture of rat portal vein. The availability of activator calcium for the contraction was modified by changing the ionic composition of the Krebs Ringer bicarbonate medium (KRB) or by using pharmacological agents such as nifedipine or KCl. In control conditions (KRB media) magnitude of IDT was 10.61 +/- 0.56 mN (n = 13). Addition of increasing concentrations of SNP (non cumulative) diminished IDT in a dose related manner. Tonic component of 60 mM KCl evoked contracture decayed 27.04 +/- 10.9% (n = 6) after 10(-4)M SNP incubation. Relaxant effect of SNP was more pronounced in the presence of nifedipine 10(-10)M (72.35 +/- 7.5% of inhibition, n = 6). The sensitivity of the preparation to SNP was strongly reduced in conditions of diminished Ca+2 efflux (slow sodium media = KRB sucrose). Experiments here presented support the hypothesis that the vasodilator effect of SNP could be attributed to an enhanced Ca+2 efflux from the vessel.

The purpose of this study was investigate the effect of depolarizing (high K+, procaine 5 mM, high K+-Ca2+ free) or hyperpolarizing (K+ free) solutions on the generation and release of prostaglandins (PGs) E and F from the rat uterus. The output of PGs in the bathing solution was measured by bioassay. Results are expressed as ng/g dry weight/min. Under basal conditions in Krebs Ringer Bicarbonate medium, the total output of PGs (E + F) was 12.8 +/- 0.9, 20.5 +/- 2.5 and 39.1 +/- 4.3 ng/dw/min at 0-60, 60-80, 80-100 min intervals respectively, the major proportion being PGF like material in all cases. When the strips were bathed in depolarizing solution the total output increased significantly PGE being the most augmented. However, when K+ free solution was used there was a marked reduction in prostaglandins release as compared with basal conditions or depolarizing media. These results can not be attributed to osmotic effect, muscular work or neurotransmitter release from nerve endings. A close relationship between the variations in membrane potential and prostaglandins release seems to indicate that both parameters might correlate well.

Effects of calcium antagonists on spontaneous mechanical activity and pharmacological reactivity of isolated rat portal vein were investigated. Prenilamine (PREN) 2 X 10(-4) M, verapamil (VER) 2 X 10(-5) M and nifedipine (NIF) 3 X 10(-8) M abolished spontaneous phasic contractions. In veins incubated in calcium-free medium plus PREN, VER or NIF, readmission of calcium restored mechanical activity up to similar control values when [Ca2+]0 reached 4.88 mM. Contractures evoked by epinephrine (EPI) 2.5 X 10(-5) M or KCl 90 mM were diminished in a similar degree by all three antagonists, its pharmacological potency being NIF greater than VER greater than PREN. Tonic component of contracture was significantly more depressed than phasic. Contracture evoked by methoxamine 10(-4) M was impaired by prazosin 10(-8) M as well as by NIF 3 X 10(-10) M. The alpha1 antagonist also blocked EPI contractile effects. Comparative studies were performed in isolated rat tail ventral artery; contractions evoked by KCl 120 mM or EPI 5 X 10(-5) M or methoxamine 10(-4) M were differentially affected by calcium omission or by NIF 3 X 10(-8) M. Results support the hypothesis that calcium antagonists act mainly by interfering with calcium influx across cell membrane without selective action upon voltage or receptor operated channels.

Conflicting reports exist about the effects of diabetes on vascular function. In the present study we investigated (1) the influences of diverse stages of diabetes on mechanical activity and pharmacological reactivity of portal vein and tail ventral artery isolated from male rats 7, 21 or 30 days after alloxan injection (150-180 mg/kg) and (2) the effects of in vitro or in vivo insulin treatment. Various parameters were used to assess the diabetic state (serum glucose levels, body weight, percentage of glycosylated hemoglobin and glucosuria). Isometric developed tension of portal vein from control rats was 10.86 +/- 0.41 mN (n = 54), and was enhanced significantly in diabetics (+56% at 21 days and +45% at 30 days; p less than 0.001 vs. controls). When challenged with noradrenaline, portal veins from diabetics exhibited a greater contractility and lower reactivity (as reflected by EC50 values). The magnitude of responses to KCl remained similar to those obtained in controls, but nonetheless the reactivity seems to be higher. Tail ventral artery from diabetics also exhibits a greater contractility in response to noradrenaline with no significant changes in EC50 values. The results demonstrate that diabetes affects mechanical performance of the vascular smooth muscle in a differential manner depending on the stage of the endocrinopathy and on the types of vessel studied. These modifications were not avoided by insulin treatment.

The effects of different pharmacological agents on the isometric developed tension (IDT) of right ventricles isolated from chronic chagasic C3HS mice were studied. The IDT in ventricles of chagasic animals was lower than in ventricles of normal mice (P less than 0.01). Chagasic ventricles exhibited hyperreactivity to norepinephrine but not to epinephrine. This hyperreactivity was masked by propranolol and not by dibenamine. Acetylcholine produced a reduction of IDT to similar values in normal and chagasic myocardia. The possibility that the effect of the drugs tested might not result from specially beta adrenoceptor-mediated reactions, but from alterations at other cellular sites is discussed.