CHANGES OF RIGHT ATRIAL MYOENDOCRINE CELLS DURING HYPERTENSION
AND AFTER ARTERIAL PRESSURE DECREASE
V.F. Maksimov, I.M. Korostyshevskaya,* S.A. Kurganov, A.L. Markel,
N.S. Rudenko, G.S. Jakobson
State Research Institute of Physiology and Fundamental Medicine, Siberian Branch of RAMS, Novosibirsk;
* e-mail: kor@physiol.ru
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.
Key words: cardiomyocyte, natriuretic peptides, arterial hypertension, losartan, electron microscopy
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