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.

Structural characteristics of renomedullary interstitial cells of hypertensive ISIAH rats.

The structural characteristics of the renal medulla and its interstitial cells were studied in hypertensive ISIAH rats (in comparison with normotensive WAG rats) in order to clear out the role of the renomedullary interstitial cells in the mechanisms of AP regulation. Morphometric electron microscopic analysis and immunohistochemical studies in ISIAH rats detected the initial signs of the renomedullary sclerosis. The renomedullary interstitial cells of ISIAH rats were characterized by higher numerical density and were larger in size, with a higher volumic share of their secretory granules.

Chromogranin location in the adrenal glands of ISIAH rats.

Comparative immunohistochemical and electron microscopic study of the adrenals from hypertensive ISIAH rats and normotensive WAG rats (control) showed a more intense reaction to chromogranin A in the ISIAH adrenal in comparison with the control. Electron microscopy and morphometric analysis showed high volume and numerical densities of the secretory granules in chromaffin cells of hypertensive rats. The results indicate stimulation of the adrenal medullary substance in ISIAH rats.

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.

Structural characteristics of renal glomerular system in ISIAH rats under conditions of chronic stress and preventive hypotensive drug therapy.

The effects of chronic stress on the structure and function of the renal glomerular system were studied in hypertensive ISIAH rats treated with hypotensive drugs during the early ontogeny. The morphometric parameters of the renal glomerular system, characteristic of each of the experimental animal groups treated by enalapril, losartan, or terazosin in early age virtually did not change under conditions of stress exposure. These results indicate a persistent delayed nephroprotective effect of these drugs.