AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 1 76-R81, Copyright © 1993 by American Physiological Society
Effect of elevated atrial pressure on plasma renin activity in hypotensive fetal lambs
A. U. Sheikh, L. K. Washburn, R. K. Jaekle and J. C. Rose
Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, Wake Forest University Medical Center, Winston-Salem, North Carolina 21757.
In adults, renin secretion is stimulated by reductions in arterial pressure
and inhibited by increases in atrial pressure. In the late gestation fetus,
a fall in arterial pressure stimulates renin secretion, but it is unknown
whether elevation of atrial pressure will alter such an increase. Therefore
we studied the effect of elevated atrial pressure on renin secretion in the
presence of nitroprusside-induced arterial hypotension. Thirteen fetal
lambs at 127.9 +/- 0.9 days of gestation were prepared 5 days before study
with inflatable pulmonary artery occluders and right atrial, vascular, and
amniotic catheters. Each fetus underwent two protocols (hypotension and
hypotension with occlusion) using a randomized block design. Nitroprusside
reduced arterial pressure by 34% in both groups. Right atrial pressure
during the course of hypotension was significantly higher in the occlusion
group (F = 14.2, P = 0.001). Plasma renin activity increased similarly in
both groups during hypotension (F = 6.0, P = 0.003). Elevated right atrial
pressure did not alter hypotension-induced renin secretion in the fetus.
