[SECRETORY ACTIVITY OF ATRIAL CARDIOMYOCYTES IN NORMOTENSIVE AND HYPERTENSIVE RATS DURING STRESS].

The pioneer overall ultrastructural and immune-enzymatic evaluation of the secretory activity of atrial myoendocrine cells in WAG strain (control) and in ISIAH rats with inherited stress induced arterial hypertension has been carried out. It was revealed that under basal conditions the cardiac hormone synthesis, storage and secretion in myoendocrine cells of hypertensive rats were certainly intensified, and the atrial natriuretic peptide (ANP) blood concentration was reliably higher than in normotensive WAG rats. All rats demonstrated the unidirectional reaction during the subchronic restraint stress: the ANP release was depressed, the peptides accumulated in the cardiomyocyte numerous large secretory granules, and ANP blood concentration 6 times decreased, while interline differences preserved.

[C-TYPE NATRIURETIC PEP- TIDE: WHAT, WHERE AND WHAT FOR IS THIS?].

The up-to-day world-wide data about the structure, distribution, and physiological effects of the most poorly known among the natriuretic peptides--the C-type (CNP)--are summarized in the review. Despite its name, this peptide does not stimulate sodium excretion but shares the prominent vasodilating and antyproliferating effects in different organs and tissues. The special emphasis is attended to CNP functions in central nervous system.

Inhibition of secretory activity of atrial myocytes in hypertensive rats after losartan treatment.

Male ISIAH rats with inherited stress-induced arterial hypertension (BP 174.0 ± 1.3 mm Hg) received antagonist of angiotensin II receptors losartan in a dose of 10 mg/kg/day for 16 days.

Cardiac natriuretic peptides and development of hereditary hypertension in rats.

Ultrastructure of the right atrial cardiomyocytes of suckling ISIAH rats was studied to clarify the role of cardiac natriuretic peptides in hypertension development during the period when blood pressure is not yet elevated. Cardiomyocytes diameter was significantly greater, Golgi complex was more developed, and granules in the sarcoplasm were more abundant in ISIAH rats as soon as on postnatal day 12 in comparison with age-matched normotensive animals. The smaller diameter of granules and their qualitative composition (ratio of forming, mature, and dissolving forms) attest to active synthesis and release of secretory product.

Delayed effect of hypotensive drugs on blood pressure and structure of the myocardium in hypertensive ISIAH rats during chronic stress.

Administration of antihypertensive drugs alpha(1)-adrenoceptor antagonist and Ca(2+) channel blocker during early ontogeny had various delayed effects on blood pressure in ISIAH rats with inherited stress-induced arterial hypertension under resting conditions and chronic stress. The drugs did not prevent the development of myocardial hypertrophy. Chronic stress had little effect on myocardial structure in adult animals.

Functional morphology of chorioallantoic vascular network in chicken.

The formation, development, and reduction of the capillary network in the chicken chorioallantoic membrane on days 7-20 of egg incubation were studied by light and electron microscopy with morphometry. Specific features in the architectonics and structure of the mesodermal large vessels and their connection to the suprachoroidal capillaries for provision of adequate gas exchange are shown.

Structural characteristics of cardiomyocytes in the right atrium of NISAG rats.

Electron microscopy and stereomorphometric analysis of hypertrophic cardiomyocytes in the right atrium of NISAG rats revealed signs of activation of biosynthetic processes: increased relative volume of euchromatin (compared to Wistar rats), high density of nuclear pores, presence of large numerous Golgi complexes, and well-developed endoplasmic reticulum. The numerical density of secretory granules in the cytoplasm of cardiomyocytes in NISAG rats significantly surpassed that in Wistar rats. However, these granules in NISAG rats were smaller than in Wistar rats.

Pathophysiological aspects of experimental myocardial infarction during arterial hypertension.

We compared the results of clinical and experimental studies of endocrine parameters in patients with myocardial infarction and arterial hypertension and NISAG rats with hereditary stress-induced arterial hypertension during experimental myocardial infarction. Changes in the content of corticosterone, aldosterone, insulin, triiodothyronine, and thyroxin were similar in animals and patients with myocardial infarction and arterial hypertension. The disadaptive course of myocardial infarction against the background of arterial hypertension can be explained by reduced compensatory capacity of the myocardium.

Effect of chronic stress during early postnatal ontogeny on structural characteristics of the myocardium and glomerular apparatus of the kidneys in NISAG rats.

We studied structural characteristics of the myocardium and glomerular apparatus of the kidneys in 3-week- and 6-month-old male NISAG rats (hereditary stress-induced arterial hypertension) subjected to handling on days 1-21 of postnatal ontogeny. The animals were daily isolated from mothers for 10 min. Handling did not modulate the development of arterial hypertension and typical morphological signs in the myocardium and kidneys.

Activation of nucleolar DNA expression in hepatocytes by glucocorticoids and high density lipoproteins.

A novel mechanism of protein biosynthesis regulation in liver under the action of reduced forms of steroid hormones (tetrahydrocortisol) and apolipoprotein A-I (apoA-I) is presented. Kupffer cells play an important role in uptake of the cortisol and high density lipoproteins (HDL) as well as in formation of the active complex, tetrahydrocortisol+apolipoprotein A-I (THC-apoA-I). If macrophages are stimulated by lipopolysaccharides (LPS), these processes enhance dramatically, thus causing parallel activation of nucleolar DNA expression and ribosome formation in hepatocytes.

Peculiarities of myocardial structure in rats with hereditary hypertension reared by normotensive females.

Morphometric analysis revealed no signs of myocardial hypertrophy at the tissue and ultrastructural levels in 3-week-old NISAG rat pups reared by normotensive Wistar females. The severity of myocardial hypertrophy in these animals aging 6 months was similar to that in NISAG rats reared by natural mothers. However, raising conditions during the early ontogeny form compensatory structural changes in the myocardium of rats with genetically determined hypertension.