CONTROL OF ALDOSTERONE IN NORMAL AND HYPERTENSIVE PREGNANCY - EFFECTSOF METOCLOPRAMIDE

To test whether factors other than angiotensin II (AII) are important in the control of aldosterone during pregnancy, we examined the inhibi tory effects of dopamine upon aldosterone release during normal pregna ncy in women with pregnancy-induced hypertension (PIH) and in normal a ge-matched non-pregnant women, using the dopamine antagonist metoclopr amide. Plasma renin (PRC), plasma aldosterone (PAC), and serum cortiso l concentrations were measured before and 30 minutes after intravenous metoclopramide in 6 non-pregnant women during both phases of their me nstrual cycle, 6 women taking oral contraceptive pills (OCPs) during b oth halves of their menstrual cycle, 6 normal third-trimester primigra vidas and 9 women with PIH. All were sodium replete and eating an adli bitum diet. Six pregnant and 6 non-pregnant women served as controls a nd had the same measurements before and after 2 ml intravenous saline instead of metoclopramide. Baseline PRC, PAC and cortisol were higher in normal pregnant than non-pregnant women and PRC was reduced signifi cantly from values for normal pregnancy in those with PIH. Serum corti sol was elevated significantly in women taking OCPs compared with othe r non-pregnant women (P < 0.05). PAC increased following metoclopramid e in every subject, but PRC and cortisol remained unchanged. PAC, PRC or cortisol were not altered significantly over the same time period i n control subjects. Although the percentage increment in PAC following metoclopramide was greater in women with PIH than in normal pregnant women (P <0.05), absolute changes were not significantly different bet ween these two groups. Our findings demonstrate that dopamine exerts c onsiderable inhibitory influence upon aldosterone release in both non- pregnant and pregnant women despite markedly elevated aldosterone conc entration in pregnancy. This effect is apparent in both normotensive p regnant women and in those with PIH.