Role of cardiopulmonary receptors in reflex control of renin release in man.

ABSTRACT

Animal studies have shown that renin release is reflexly modulated by cardiopulmonary and arterial baroreceptors, and that during changes in posture the former receptors play a major role. This role has been challenged in man, however, by reflex modulation of renin secretion which has been claimed to take place only if arterial and cardiopulmonary receptor areas are engaged together. We studied 19 normotensive and essential hypertensive subjects in which plasma renin activity was assessed by radioimmunoassay during a mild 20 min increase and a mild 20 min reduction in central venous pressure (+1.1 +/- 0.2 mmHg and -2.6 +/- 0.4 mmHg). The increase and reduction in central venous pressure were accompanied by no change in systolic blood pressure, diastolic blood pressure and heart rate which indicated that the increased and reduced stimulus had involved only cardiopulmonary receptors and not arterial baroreceptors as well. During the increase in central venous pressure plasma renin activity showed a significant (P less than 0.01) reduction (-18 +/- 3%) whereas during the reduction in central venous pressure it showed a significant (P less than 0.01) and more marked increased (+64 +/- 17%). The plasma renin activity increase observed during lower body suction was not significantly different from that observed during a 20 min tilting, a manoeuvre that reduced central venous pressure to an extent similar to that observed during lower body suction, but that also deactivated carotid baroreceptors by positioning the carotid sinuses above the heart and reducing their transmural pressure. Thus in normotensive and hypertensive humans renin release can be reflexly modulated by selective engagement of cardiopulmonary receptors.(ABSTRACT TRUNCATED AT 250 WORDS)