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Biomedical subjects

V Pelouch

Publications and source records attributed to V Pelouch.

At least 55 records · Page 3Linked to original sources
PubMed1987

Different effect of propranolol and verapamil on isoprenaline-induced changes in the chick embryonic heart.

Isoprenaline (IPRO) has been reported to cause pathological lesions of the embryonic heart. The purpose of the present study was to ascertain whether the development of IPRO-induced changes can be reduced--similarly as in adults--by beta blockade or calcium antagonists. IPRO was administered to 10-day-old chick embryos intraamnially (i.a.) in a dose of 2 X 10 mg.kg-1 per 48 h; propranolol (Inderal) and verapamil (Isoptin) were injected i.a. in a dose of 1.0 or 10.0 mg.kg-1 before each injection of IPRO. It was found that propranolol completely blocked the cardiac IPRO-induced changes, i.e. cardiomegaly, avascular areas and elevation of cAMP. On the other hand, verapamil was found to have no protective effect in any dose used. Furthermore, it increased the mortality of experimental embryos. This fact support the hypothesis that cardiac sensitivity to calcium antagonists may differ during prenatal development.

Animals↗
PubMed1987

Increased affinity to substrate in sarcolemmal ATPases from hearts acclimatized to high altitude hypoxia.

It has been well documented that acclimatization to chronic high altitude hypoxia involves a complex of adaptation changes which are capable of protecting the myocardium in diverse situations such as in acute hypoxia, coronary occlusion-induced ischaemia or isoprenaline-induced calcium overload. Since many of the former changes concern membrane functions, namely those of the sarcolemma, the activities and kinetic properties of sarcolemmal Mg2+-, Ca2+- and (Na+ + K+)-ATPase were investigated in right heart ventricles of rats acclimatized to intermittent high altitude hypoxia simulated in a barochamber. In the course of the experiment, the ventricles were subjected to a special anoxic test in vitro. The high altitude induced increase in cardiac tolerance to anoxia was not accompanied by any preservation of the sarcolemmal ATPase activities. On the contrary, membrane preparations obtained from the right ventricles of hearts acclimatized to high altitude exhibited significantly lower ATPase activities in comparison to non-acclimatized controls. The significant diminution in Km values of ATPases established in acclimatized hearts points to an increase in the affinity of their active sites to ATP. The latter effect is in agreement with the lowered rate of both the decrease in ATPase activities and the reduction of contractility in acclimatized hearts during the anoxic test, as well as with the considerably improved postanoxic reparability of contractions as compared to the controls. It is being concluded that the sarcolemmal changes at the level of ATPases involved in ionic transport processes represent an integral part of the adaptation complex to chronic high altitude hypoxia.

Acclimatization↗
PubMed1987

Increase and regression of the protective effect of high altitude acclimatization on the isoprenaline-induced necrotic lesions in the rat myocardium.

Cardiac resistance to the cardiotoxic effect of isoprenaline--ISO (single dose of 0.1 mg X kg-1) was studied in rats acclimatized to intermittent high altitude--IHA (barochamber, 8 h a day, 5 days a week, stepwise up to 7000 m). The extent of lesions was evaluated quantitatively by means of the increased accumulation of 203HgCl2. Five weeks' acclimatization was followed by a marked increase in the resistance of the myocardium to the necrogenic effect of ISO; this effect was more expressed in the left ventricle, so that the right to left difference generally observed under normoxic conditions disappeared. The increased resistance of the myocardium to ISO-induced damage persisted long after the animals had been returned to normoxic conditions; even six weeks after the last hypoxic exposure the sensitivity of the myocardium to damage had still not returned to the values of unacclimatized animals.

Acclimatization↗
PubMed1986

Ontogenetic differences in cardiac sensitivity to verapamil in rats.

The degree of a negative inotropic response of the isolated right ventricle to verapamil as well as the mortality rate were studied in rats during their postnatal development. Male Wistar rats aged 3, 15, 30, and 90 days were used. The isolated right ventricle was incubated in a glucose-free solution with a mixture of 95% O2 and 5% CO2 and electrically stimulated. The amplitude of isotonic contractions (AIC) was registered. In 90-day-old rats, AIC was 74.1 +/- 6.2% of initial amplitude 45 min after administration of verapamil; in 30-day-old, 41.1 +/- 6.4%; in 15-day-old, 38.2 +/- 4.1%; and in 3-day-old rats, only 2.6 +/- 1.5. The difference between the 3-day-old rats and all older groups was statistically highly significant. The mortality rate of verapamil-treated rats increased with decreasing age of animals. It is concluded that the sensitivity of the rat myocardium to verapamil is age dependent: the negative inotropic effect of this drug increases with decreasing age of the animal. This indicates a possible risk in the therapeutic use of verapamil when given to newborns and infants.

Aging↗
PubMed1986

The effect of oxidized isoprenaline on the chick embryonic heart.

Intra-amnial administration of isoprenaline (IPRO) to chick embryos induces a number of myocardial lesions. The purpose of the present study was to investigate whether similar changes may also be induced after injection of spontaneously oxidized isoprenaline and commercially obtained adrenochrome. Cardiotoxicity of these substances has been demonstrated in adult animals. IPRO, oxidized IPRO, or adrenochrome were administered intra-amnially to 10-day-old chick embryos at doses of 0.1, 1.0, 10.0, and 100.0 mg X kg-1. Parallel experimental groups received propranolol at a dose of 1 mg X kg-1, 15 s before injection of IPRO or oxidized IPRO. The cAMP level in the heart was determined by radioimmunoassay 2 and 30 min after administration of IPRO, oxidized IPRO, or adrenochrome at a single dose of 10.0 mg X kg-1. It has been found that in embryos the effect of IPRO and oxidized IPRO is dose dependent. The rise in mortality and development of cardiomegaly together with increased hydration and disturbances of the development of coronary vascularization were highly significant starting from the dose of 10 mg X kg-1. Furthermore, both drugs significantly increased cAMP levels in the embryonic heart. On the other hand, the administration of adrenochrome was without any effect. The changes induced by IPRO were prevented by the administration of the beta-blocking agent propranolol; the lesions induced by spontaneously oxidized IPRO were, however, prevented only partially.

Adrenochrome↗
PubMed1986

Transport ATPases in the erythrocytes of rats acclimatized to intermittent altitude hypoxia.

The activity of Na+/K+- and Ca2+-ATPase and some allosteric properties of Na+/K+-ATPase were studied in whole erythrocytes and their membrane preparations (ghosts) from rats exposed to intermittent altitude hypoxia (10 and 24 exposures, 8 h/day in an altitude chamber, stepwise up to an altitude of 7,000 m). Ca2+-ATPase activity was increased both in whole erythrocytes and ghosts after the first phase of acclimatization (10 exposures). In a standard incubation medium (containing 3 mmol.l-1 MgCl2 ), Na+/K+-ATPase activity in the ghosts was also increased after the initial phase of acclimatization whereas in whole erythrocytes Na+/K+-ATPase was only decreased in the regression phase. At high MgCl2 concentrations (12 mmol.l-1) changes of Na+/K+-ATPase activity both in whole erythrocytes and in the ghosts followed similar time course with a pronounced increase in the first phase of acclimatization (10 exposures) followed by an abrupt drop (24 exposures) and then by a gradual normalization in the regression phase. Sensitivity of the enzyme to mounting MgCl2 concentrations was increased in the ghosts at the end of acclimatization and was decreased in whole erythrocytes during acclimatization and especially in the regression phase. It has been suggested that chronic altitude hypoxia leads to the alteration of cooperative interaction of the Na+/K+-ATPase subunits in the erythrocyte membrane and accumulation of some factor in the cells inhibiting this enzyme.

Acclimatization↗
PubMed1985

Phospholipid content in the compact and spongious musculature of the carp heart (Cyprinus carpio).

The phospholipid content of the spongious and compact musculature of the heart of the carp (Cyprinus carpio) was compared. The content of phospholipids is higher in the spongious musculature, the greatest difference being in the content of diphosphatidylglycerol: 2.53 mumol P . g-1 wet weight in the spongious layer and 1.29 mumol P . g-1 wet weight in the compact one. In both tissues plasmalogens represent 20-27% of the tissue content of choline and ethanolamine phosphoglycerides.

Animals↗
PubMed1985

Response of the rat cardiovascular system to a moderate altitude in connection with endurance training.

The authors investigated whether an altitude of 1,350 m would affect the rat cardiovascular system in the same way as genuine altitude hypoxia and the way it would take effect when combined with endurance training in the form of swimming It was found that 8 weeks spent at this altitude led to an increase in absolute and relative heart weight, to right ventricular hypertrophy, and to increased resistance of the myocardium to acute anoxia. Physical training at a moderate altitude resulted in an increase in the relative weight of the musculature of both the right and the left ventricle and of the septum. Unlike low altitude training, however, growth of the two compartments of the heart was proportional. The resistance of the myocardium of trained animals against anoxia was the same, irrespective of whether they trained at a low or a high altitude. The results show that even a moderate altitude is not a matter of indifference for the rat organism, but that it leads to characteristic manifestations of altitude hypoxia in the cardiovascular system.

Altitude↗
PubMed1984

Comparison of cardiopulmonary responses of male and female rats to intermittent high altitude hypoxia.

Intermittent high altitude hypoxia (8 hours a day, 5 days a week, stepwise up to the altitude of 7000 m, total number of exposures 24) induced in male and female rats, chronic pulmonary hypertension and right ventricular hypertrophy. No significant sex differences were found in both these parameters. A significant sex difference was demonstrated in the resistance of the cardiac muscle to acute anoxia in vitro: the myocardium of control female rats proved to be significantly more resistant to oxygen deficiency. Intermittent altitude hypoxia resulted in significantly enhanced resistance in both sexes, yet the sex difference was maintained. Sex differences were further observed in the growth response of experimental animals to the acclimatization process. Whereas the body weight of male rats exposed to intermittent altitude hypoxia was significantly lower, hypoxic females had body weights comparable to those of control animals.

Altitude↗
PubMed1984

Adenylate cyclase activity and localization in necrotic and non-necrotic areas of rat myocardium after injection of high doses of isoproterenol.

With the help of electron microscopical cytochemical investigation, adenylate cyclase activity was shown to be strongly reduced in the necrotic tissue 24 h after isoproterenol injection. However, no changes were found in the basal activity of adenylate cyclase in this tissue region by biochemical determination, while the isoproterenol-stimulated activity was markedly reduced under corresponding conditions in the same tissue. It was suggested that these discrepancies between cytochemical and biochemical findings are due to partial solubilization of the adenylate cyclase protein by damaging the membrane structure.

Adenylyl Cyclases↗
PubMed1983

Effect of beta adrenergic blocking agents on erythropoiesis in rats.

The purpose of the present study was to analyze the effect of two different beta blocking agents, metipranolol (Trimepranol) and dl-propranolol (Inderal), upon erythropoietin production, erythropoietin responsive cell compartment and erythrocyte production. The effect on erythropoietin production: in rats metipranolol or dl-propranolol was injected daily in a single dose of 10 mg/kg b.wt. On the 5th day, the rats were exposed to an atmospheric pressure of 353.7 torr (47.1 kPa, 6000 m) to stimulate erythropoietin production. The onset of hypoxic exposure was started 1, 4, 12 or 24 hr after the last injection of beta blocking drugs. After the termination of hypoxia, erythropoietin plasma levels were determined in polycythemic mice. The rats treated with metipranolol 1 and 4 hr before hypoxia produced significantly less erythropoietin in response to hypoxia than saline-treated control animals. The effect on erythropoietin responsive cell compartment: polycythemic mice were treated with metipranolol or dl-propranolol in doses of 10 to 40 mg/kg b.wt. and with an erythropoietin standard. Radioiron incorporation into red blood cells in control mice and in mice pretreated with beta blocking agents was not significantly different. The effect on erythrocyte production: in rats treated daily with metipranolol in a single dose of 10 mg/kg b.wt., for a period of 10 days, the rate of erythropoiesis measured by the incorporation of 59Fe into red blood cells was decreased, dl-propranolol (10 mg/kg b.wt.) did not reduce the rate of erythropoiesis. Our results demonstrate that the changes in erythropoiesis after administration of metipranolol may be caused by reduction of erythropoietin production with a consequent reduction of the erythrocyte production rate.

Adrenergic beta-Antagonists↗