[Changes of right atrial myoendocrine cells during hypertension and after arterial pressure decrease]

It is well known now that atrial cardiomyocytes carry out both contractile and endocrine activities--they synthesize, accumulate in specific secretory granules and release the natriuretic peptides. The main physiological effects of natriuretic peptides are antagonistic to the renin-angiotensin-aldostrol system, but their role in the development of hypertension is still disputable. The aim of this investigation is to estimate using electron microscopy the secretory activities of atrial myoendocrine cells in rats with inherited stress-induced arterial hypertension (ISIAH stain). It has been shown that myoendocrine cells in the ISIAH rats with arterial pressure about 180 mm Hg reveal morphological features of increased synthesis, extra accumulation and release of natriuretic peptides compared with normotensive control rats. In the ISIAH rats treated with losartan (angiotensin II receptor blocker) and therefore having a sustained decrease in arterial pressure to 140 mm Hg, changes in granular pool composition, reduction of the number and diameter of the secretory granules, reduction of Golgi complexes, and increased intracellular degradation of secretory stores were found in the myoendocrine cells. At the same time the marked capillary hyperemia and interstitial edema in the myocardium were observed. Thus, in rats with severe inherited hypertension, the secretory activity of heart myoendocrine cells is sharply increased and directly depends on the arterial blood pressure level. This proves that natriuretic peptides actively participate in the regulation of hemodynamics during with cardiovascular pathology.

[Cardiac natriuretic peptides and hypertension: experimental study]

The peculiarities of cardiac natriuretic peptide secretion have been investigated during ontogenesis using the hypertonic disease model in ISIAH rat line (with inherited stress induced arterial hypertension). The qualitative and quantitative ultrastructural investigations of right atrium myocardium revealed that the cardiac hormonal synthetic and secretory activities in ISIAH rats are higher as compared with normotensive even-aged rats from control group. Secretory hyperactivity of atrial myocytes in ISIAH rats during early ontogeny precedes the manifestations of hereditary hypertension. Natriuretic peptides present the hypotensive circuit of hemodynamic regulation during the whole ontogeny and the complementary chain in hypertension development.

[Cardiovascular peculiarities in hypertensive rats (Hsiah strain) after antihypertensive drug intervention during juvenile period of life]

Treatment with different types of antihypertensive drugs during second month age has not prevented development of arterial hypertension and myocardial hypertrophy in the adult rats with inherited stress-induced arterial hypertension. At 6 months of age, the 11% attenuation of basal blood pressure has beet achieved only in the rats treated with angiotensin-converting enzyme inhibitor enalapril. Nevertheless, they expressed the most pronounced left ventricular hypertrophy. The unfavorable tissue and ultrastructural abnormalities were revealed in the myocardium of the rats which received the alpha1-adrenoceptor blocker terazosin. The delayed effects of losartan (angionetsin II receptor antagonist) and corinfar (calcium channel antagonist) on the myocardial structure were inessential.

[Stereomorphometric study of target organs in rats with hereditary stress-induced arterial hypertension at different periods of postnatal ontogenesis under changed conditions of nursing]

In rats with inherited stress-induced arterial hypertension (ISIAH strain), myocardium, adrenal gland, and renal glomerular apparatus were studied at different periods of postnatal ontogenesis (3 weeks and 6 months) to assess the influence of the changed conditions of nursing on the development of a hypertensive status and structural-functional characteristics of target organs. It was demonstrated that nursing of rats by foster normotensive Wistar females exerted a modulating influence upon the realization of stress-determined program of arterial hypertension development, seemingly delaying it and alleviating the negative consequences in respect to the target organs, through increased effectiveness of recruitment of adaptive-compensatory organism reserves, however, on the whole, it did not interrupt this program.

[Structure of the adrenal gland in rat strain with hereditary stress-induced arterial hypertension nursed by Wistar dams]

The comparative investigation of the adrenal structure in two groups of rats of Inherited Stress-Induced Arterial Hypertension (ISIAH) strain was conducted. The animals of the first group were nursed by normotensive Wistar rats, while those of the second (control) group were reared by their own mothers. The volume of the adrenal medulla in rats of the first group was found to exceed that in the second group. In the adrenal zona glomerulosa and zona fasciculata of 3-week-old rats of the first group parenchymal-stromal ratio and the average volume of adrenocorticocytes were lower than those in the animals of the second group. This was accompanied by a decrease in mitochondrial volume density and accumulation of lipid droplets in the cytoplasm, indicating a reduction of hormone-producing activity of endocrinocytes in the animals the first group as compared to controls. By 6 month of age, arterial pressure and quantitative parameters of adrenal medulla and cortex in the animals the first group were..... as compared to those in the second group. It is suggested that the nursing of ISIAH rat pups by normotensive Wistar dams had modulating effect on the adrenal structure and therefore on arterial hypertension development.

[Ultrastructural changes of kidney corpuscles in rats with hereditary stress-induced arterial hypertension]

Comparative electron microscopic study of glomerular apparatus was performed in 6-month old Wistar rats and in rat strain with inherited stress-induced arterial hypertension (ISIAH). It was shown that this stage of hypertensive status formation was characterized by hypertrophy of renal corpuscles, accompanied by structural changes of all their cellular and noncellular components. These included abrupt capillary constriction or dilation, endothelial flattening, podocyte hypertrophy and flattening of their cytopodia, thickening of basal lamina, mesangial volume expansion and increase in the number of intercapillary processes of mesangial cells. Complex of these signs suggests a disturbance of glomerular capillary blood circulation and a functional podocyte stress, compensating these microcirculatory disturbances. Changes in basal membranes and mesangium are indicative of not only increase in filtration barrier functional load, but also of initial stages of glomerular sclerosis.

[Structural characteristics of the adrenal cortex from rats with stress-induced hereditary arterial hypertension in the late postnatal ontogenesis]

The comparative investigation of the adrenal cortex in hypertensive (INHERITED STRESS-INDUCED ARTERIAL HYPERTENSION--ISIAH) and normotensive strain (Wistar) 12-months age rats was performed. The structural signs such as the lowering of the mitochondria volume involved in steroid synthesis in showed more notable age-related reduction of steroidogenesis in the adrenal glomerular and fascicular zones and in the ISIAH rats. The lowering of the cell steroidogenesis was compensated by the adrenal glomerular and fascicular zones and hypertrophy as a result the adrenocorticocytes hyperplasia. At the same time the more considerable sclerotic changes of the adrenal cortex periendothelial space were demonstrated in the ISIAH rats. The results obtained give evidence that reducing potential of compensatory possibilities of the adrenal cortex of the ISIAH rats in the late postnatal ontogenesis period cause high probability of adaptative-compensatory mechanisms failure and pathological process aggravation in these animals.

[The specificity of lipid metabolism in hereditary arterial hypertension induced by stress]

Studies of lipid metabolites in the plasma and lymph of rats with hereditary arterial hypertension induced by stress (HAHIS) showed decreased plasma and lymph pool of total cholesterol (TC) in comparison with normotensive Wistar rats. In HAHIS animals, TC concentration in the lymph was lower than in the plasma. The concentrations of triglycerides and free fatty acids in the plasma and lymph of hypertensive animals were virtually the same and higher than in normotensive ones. Plasma concentration of malonic dialdehyde (MDA) in HAHIS rats was the same as in Wistar rats, while the lymph concentration of MDA was higher than in Wistar rats. The detected lipid metabolism characteristics reflect its genotypical and phenotypical rearrangement and are a component of the "metabolic syndrome", detected in patients with essential hypertension and animals with spontaneous arterial hypertension.

[Blood pressure increase in foster mothers in ISIAH and Wistar rats: effect of reciprocal cross-fostering]

Maternal arterial blood pressure (ABP) of hypertensive (ISIAH) and normotensive (Wistar) rats rearing their natural litter or litter of opposite strain, was assessed when the pups were 1.5-, 3- and 4-month old and compared with the ABP of these rats prior to their mating. The ABP was increased in both breeds of rat strains for either cross-fostered or infostered pups. No ABP changes were observed in control rats.

[Metabolic damage to the myocardium in normotensive and hypertensive rats (morphometric analysis)]

Morphological changes of myocardium were demonstrated in normotensive Wistar rats and in rats with inherited stress-induced arterial hypertension 1, 7 and 30 days following adrenaline induced damage. In acute period contracture damage to cardiomyocytes was more pronounced in Wistar rats. Death of the fraction of cardiomyocytes is compensated by hypertrophy of the surviving cells already by d 7. In hypertensive rats' hypertrophied myocardium on d 1 microcirculatory bed is more impaired, while regenerative processes in cardiomyocytes are delayed and defective, which leads to dystrophy and degeneration by the end of the experiment. It is concluded that the course and prognosis of myocardial metabolic injury is determined by its initial state and potential compensatory resources.

[The protective reaction of the myocardium to ischemic damage]

The morphological and functional consequences of epinephrine-induced myocardial infarction were studied in normo- (Wistar) and hypertensive (ISIAH) rats. After experimental myocardial infarction there was an irreversible transition to the "worn-out" stage or "plastic damage" to the myocardium. Thus, myocardial hibernation in ISIAH rats anticipates and determines the development of myocardial stunning, i.e., irreversible myocardial damage, whereas in the normotensive animals, the protective effect of hibernation is fully shown. The ontogenetic features of myocardial response of ISIAH rats to hypoxia promote transformation of adaptive hibernation and stunning to maladaptive pathological changes causing hypoxic alterations.

[Structural features of the rat adrenal cortex with inherited stress-induced arterial hypertension in the early period of postnatal ontogenesis]

Comparative morphometric examination of adrenal cortex was carried out in 3 wks HNCAI rats with inherited stress induced arterial hypertension and normotensive Wistar rats. Relative adrenal mass, volume of cortex and its glomerular zone in HNCAI rats exceeds appropriate values in Wistar rats. Increase of adrenocorticocytes due to hyperplasia of their ultrastructural components was found. In hypertensive rats adrenocorticocyte numerical density increase due to their hyperplasia was found in adrenal fasciculate zone in contrast to glomerular one. These structural organization peculiarities in 3 wks hypertensive rat adrenal cortex reflect their elevated functional activity and may determine genetically programmed increased organism responsiveness to stress that consequently provides the grounds for the hypertensive status formation in this rat line.

[Effect of cryopreservation on the morphology of preimplantation embryos of the ISIAH rat line]

Micronuclei of preimplantation embryos of the hypertensive rat strain with inherited spontaneously induced arterial hypertension (ISIAH) are studied. Also studied are the formation of micronuclei and other morphological changes in these embryos after freezing, cryoconservation, and consequent transplantation to Wistar recipient rats. Analysis of semithin sections demonstrates that the above procedures lead to the formation of micronuclei in most embryos, while the shape of nuclei changes in only some embryos. There is a tendency towards perinuclear location of organelles and inclusions and to the partial disappearance of polarity in the majority of blastomeres. We believe that the increase in the number of micronuclei can be associated with a certain selection of embryos during cryoconservation and transplantation.

[Elevated arterial pressure in normotensive Wistar strain rats after the transplantation of embryos from hypertensive ISIAH strain rats. Inherited stress-induced arterial hypertension]

The ISIAH embryos exerted no effect on surrogate mothers if the embryos had been cryopreserved before transferring. The data obtained is discussed from the standpoint of surrogateship in medicine and possible effect of the embryo cryobanking on some inherited traits in mammals.

[The morphofunctional characteristics of the zona glomerulosa of the adrenal cortex in rats with hereditary stress-induced arterial hypertension]

Morphometrical analysis of adrenal cortex glomerular zone performed in rats with hereditary stress-induced arterial hypertension assisted in establishing important peculiarities of the zone structure. Adrenocorticocytes of adrenal cortex glomerular zone in hypertension rats are subjected to hyperplastic intercellular changes, suggesting the increase of the zone functional activity, which is substantiated by data on significantly high aldosterone concentration in plasma of these animals.

[The effect of acute hypoxia on the fatty acid composition and lipid peroxidation of the liver microsomal membranes and blood plasma in rats with different resistances to oxygen deficiency]

The experiments in rats showed the changes in the fatty acids composition of lipids of hepatic microsomal membranes and lipids of blood plasma after acute hypobaric hypoxia to depend on individual resistance of animals to oxygen deficiency. In highly resistant rats the content of unsaturated fatty acids and lipid peroxidation activity in blood plasma increased. In low-resistant rats similar changes occurred in lipids of hepatic microsomal membranes.

[Aldosterone and electrolyte content in blood and myocardium of rats after single physical load in acute alcoholic intoxication]

It is shown that acute alcoholic intoxication causes essential changes of aldosterone content and balance of electrolytes in blood plasma of Wistar rat males. The SPL test revealed the inadequate reaction in the mineral-corticoid function of the adrenal glands in the rats with acute alcoholic intoxication. The method of the free choice of the load by the experimental rats is the most optimal way to assess. The rats with acute alcoholic intoxication displayed smaller tolerance to physical load.

[Contents of aldosterone and electrolytes in blood plasma and the myocardium of rats after single physical exertion during acute alcoholic intoxication]

It was proved in experiments with male Wistar rats that acute alcohol intoxication caused significant changes in electrolytes balance in blood plasma and myocardium remaining for a long time after ethanol injection. SPL test makes it possible to reveal inadequate reaction of blood plasma aldosterone in alcohol injected rats. This fact may be considered as the fact of involving extracardiac component of compensation of myocardial functional insufficiency conditioned mainly by electrolyte unbalance. The tolerance to physical loading is significantly higher in alcohol injected rats than in intact animals.

[Glucocorticoid function of the adrenal cortex in patients with myocardial infarction: study of elimination of exogenous cortisol]

The paper yields the results of the study into the elimination of exogenous cortisol from the blood bed in 26 patients with myocardial infarction. It is concluded that the nature of cortisol elimination may reflect the natural history and prediction of myocardial infarction. In terms of the body tissue demand, two type of elimination are identified: retarded (a favorable type) and accelerated (an unfavorable type). The data on the nature of cortisol elimination may serve as an indication for glucocorticoid therapy. The baseline cortisol concentrations fail to reflect the nature of glucocorticoid metabolism in patients with myocardial infarction.

[The role of the Ca2(+)-blocking effect of alcohol in the genesis of ischemic myocardial damage]

The experiments on Wistar male rats with induced myocardial infarction have studied the role of Ca-blocking effect of acute ethanol administration in ischemic injury of myocardium. It has been established that acute alcohol intoxication led to destabilization of adaptive processes in ischemic myocardium.

[Effect of glutamic acid on the course of recovery processes in the adrenal cortex]

Glutamic acid in a dose of 1/100 of the LD50 was injected in the form of sodium salt into male and female Wistar rats for 7 days after 8- and 12-day injections of dexazone. During the first 3 days of injections, female rats received a low dexazone dose (5 micrograms/100 g bw). Injection of glutamic acid in conjunction with dexazone reduced the inhibitory effect of the latter drug on the adrenals but did not avert its inhibitory effect on the central nervous system. Prolonged injections of glutamic acid after dexazone treatment promoted more rapid and more complete recovery of adrenal function.

[Ultrastructural and cellular functional activity changes in the zona fasciculata of the rat adrenal cortex resulting form the prolonged administration of adrenocorticotropic hormone]

The fasciculata zone cell ultrastructure has been studied in addition to the level of steroidogenesis of rat adrenal glands on days 2,7 and 13 after the administration of ACTH with prolonged action. The marked changes in the ultrastructure of different cells have been noticed, some of which suggest a compensatory stimulation of hormone production, and the others indicate irreversible subcellular injuries. Changes in the cell ultrastructure show the phase character in time to correlate with changes in the activity of the corticosteroid synthesis and secretion.

[Variations in the response of adrenocortical and hepatic parenchyma of mice of different genetic strains to stress]

Distinctions in adrenal cortex and liver parenchyma responses to acute stress were found in mice of different stains. These distinctions consisted in differences in concentration of 11-OCS in blood, corticosterone and testosterone of metabolism in liver and in quantitative parameters of hepatocyte ultrastructures.

[Change in the enzymatic activity of liver carbohydrate metabolism after the one-time carbon tertrachloride poisoning of rats]

Activity of gluconeogenesic enzymes was more distinctly decreased than the activity of glycolytic enzymes within 8 and 24 hrs after a single intoxication of rats with CCl4. Within 72 hrs the enzymatic activity of glycolysis and gluconeogenesis was similar but the activity of the enzymes participating in the hexose monophosphate shunt was 2-3-fold higher as compared with the patterns characteristic for the intact animals. Mechanisms of these alterations are discussed; they are apparently related to the change in hepatocyte population due to necrosis and regeneration as well as to localization of enzymes of gluconeogenesis in central part of liver lobule.

[Changes in the ultrastructure and functional parameters of rat adrenal cortex cells in the course of reparative regeneration]

On the tenth and twenty-first days after bilateral enucleation of adrenal glands of Wistar rat-males their regeneration and mitochondria have been studied biochemically and with the electron microscope. The signs of transformation of glomerular zone cells into cells of lower gland zones have been found. The process of vertical zone transformation for glomerular cells remained under the gland capsule after the operation is shown to be accompanied by functional cell reconstruction. During the process of cell differentiation the adrenal gland cells are supposed to function by means of golocrinical secretion of some of the regenerated cells.

[Changes in rat liver lysosomes following stimulation of recovery processes in the damaged organ by triton WR-1339]

The effect of a single injection of lysosomotropic agent--Triton WR-1339 on the properties of the rat liver lysosomes and the course of pathological process during chronic toxic hepatitis were studied. Triton WR-1339 administration was followed by a more rapid restoration of the liver structure and function. A possible mechanism of the favourable effect of Triton WR-1339 is discussed.

[Effect of sex and phase of the estrous cycle on the intensity of the damage and recovery processes in the liver of rats following acute carbon tetrachloride poisoning]

Morphometric, histochemical, and electron microscope methods were applied to the study of peculiarities of Wistar rat liver damage and recovery, depending on sex and phase of the estrous cycle, and also under conditions of deficiency of sex hormones and after the beta-estradiol injection to ovariectomized animals. A marked increase of the structural alterations caused by CCl4 and inhibition of the restoration reactions in the liver of female animals, both during the natural increase of blood estrogen concentration and under the effect of exogenous estradiol, as well as the protective effect of ovariectomy were demonstrated. As for male rats, the structural damage in the liver was more expressed than in the females with a low blood estrogen level and differed but little from the changes in the female animals during increased sex steroids secretion.

[Ultrastructural and functional features of the reversibility of sclerotic liver changes in rats treated with exogenous organ specific RNA]

Ultrastructural peculiarities of hepatocytes and Kupffer's cells in rats during the spontaneous reversibility of the experimental cirrhosis of the liver under the usual conditions and also under the influence of exogenous RNA, administered by different methods, were studied. The changes in cell ultrastructure proved to correlate with those of the quantitative indices of the protein synthesizing the liver function during the hepatic cirrhosis reversibility. A positive role of the RNA influence of short duration on the intracellular reparative hepatocytes regeneration, and a negative one in case of RNA influence of long duration was revealed. Participation in the resorption of collagen both of the parenchymal cells and of the stroma was shown.

[Effect of triton WR 1339 on the ultrastructure of liver parenchymal and stromal cells in rats with chronic toxic hepatitis]

A preliminary injection of triton WR 1339 protectively influenced the chronic toxic CCl4-hepatitis. The ultrastructural peculiarities were close to the normal ones in hepatocytes, in addition to the increased triglyceride rejection from cells by means of autophagy. The revealed stimulation signs of pinocytosis in hepatocytes and the Kupfer cells are accompanied by the activation of the Golgi complex and, probably, by the increased protein catabolism in lysosomes. The signs of phagocytosis increase in the Kupfer cells were determined. It is supposed that the marked ultrastructural peculiarities of liver cells reflect a more effective restoration or a lesser injury under the influence of triton WR 1339.

[Tyrosine-alpha-ketoglutarate transaminase activity in the rat liver after partial hepatectomy and CCl4 poisoning]

Acitivity of tyrosine-alpha-ketoglutarate transaminase and induction of the enzyme by hydro cortisone were studied in rat liver tissue after partial hepatectomy and intoxication with CCl4 Administration of the hormone increased the enzymatic activity within 72 hrs after treatment with CCl4 but did not affect its value within 8 and 24 hrs. Activation of the enzyme by hydrocortisone correlated with the increased enzymatic activity observed within 20 hrs after partial hepatectomy. Possible mechanisms for activation of the enzyme, caused by endo- and exogenous factors, are discussed.

[Ultrastructure and function of zona fasciculata cells in the adrenal cortex of mice of differing genetic lines but physiologically normal]

Ultrastructure and function were studied of the cells of zona fasciculata of the adrenal cortex of male mice of strains CBA and C57B1. The results obtained point to potentially higher possibilities of the adrenal zona fasciculata in mice of strain C57B1. These data show the role of the genotype in determining the structure and functions of the cells of the adrenal cortex as well as an evident correspondence of the ultrastructural features to the specificity of functions and the level of activity of cells.

[Effect of sodium aurothiomalate in acute toxic hepatitis]

The effect of lysosomotropic agent--sodium aurothiomalate on liver damage and lysosomal changes during acute toxic hepatitis was studied. Combined administration of sodium aurothiomalete led to less extensive necrosis and to widening dystrophic areas in the hepatic parenchyma. Solubilization of the acid RNA-ase activity was decreased, and nonsedimentable activities of beta-galactosidase, cathepsin D were the same as in acute CCl4-hepatitis.