SYSTEMIC AND RENAL HEMODYNAMIC-CHANGES IN THE LUTEAL-PHASE OF THE MENSTRUAL-CYCLE MIMIC EARLY-PREGNANCY

Blood pressure decreases during early pregnancy in association with a decrease in peripheral vascular resistance and increases in renal plas ma flow and glomerular filtration rate. These early changes suggest a potential association with corpora lutea function. To determine whethe r peripheral vasodilation occurs following ovulation, we studied 16 he althy women in the midfollicular and midluteal phases of the menstrual cycle. A significant decrease in mean arterial pressure in the midlut eal phase of the cycle (midfollicular of 81.7 +/- 2.0 vs. midluteal of 75.4 +/- 2.3 mmHg, P < 0.005) was found in association with a decreas e in systemic vascular resistance and an increase in cardiac output. R enal plasma flow and glomerular filtration rate increased. Plasma reni n activity and aldosterone concentration increased significantly in th e luteal phase accompanied by a decrease in atrial natriuretic peptide concentration. Serum sodium, chloride, and bicarbonate concentrations and osmolarity also declined significantly in the midluteal phase of the menstrual cycle. Urinary adenosine 3',5'-cyclic monophosphate (cAM P) excretion increased in the luteal compared with the follicular phas e, whereas no changes in urinary cGMP or NO2/NO3 excretion were found. Thus peripheral vasodilation occurs in the luteal phase of the normal menstrual cycle in association with an increase in renal plasma flow and filtration. Activation of the renin-angiotensin-aldosterone axis i s found in the luteal phase of the menstrual cycle. These changes are accompanied by an increase in urinary cAMP excretion indicating potent ial vasodilating mediators responsible for the observed hemodynamic ch anges.