CYCLICAL CHANGES IN THE RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM DURING THE MENSTRUAL-CYCLE OF THE BABOON (PAPIO-HAMADRYAS)

This study characterizes the renin-angiotensin-aldosterone system duri ng the normal menstrual cycle in the baboon. Ten animals received a da ily dose of an ACE inhibitor or placebo in a randomized blind cross-ov er design. Data were obtained during the mid-follicular and early lute al phases of normal non-pregnant menstrual cycles. All examinations an d blood collections were performed with ketamine sedation: 7-kg by im injection. Blood pressure was recorded by sphygmomanometer. Serum ACE activity was measured by spectrophotometry. Aldosterone (ALDO), angiot ensin I(AI), and angiotensin II (All) were measured by radioimmunoassa y. Plasma renin activity (PRA) was measured by AI generation. The reni n-angiotensin-aldosterone system was found to be activated in the foll icular phase and suppressed during the luteal phase of the normal non- pregnant menstrual cycle in the baboon.