Renal Effects of Angiotensin Ii Infusions in Normotensive Pregnant and Nonpregnant Women.

• Infusion of angiotensin n has profound effects upon renal function in normotensive subjects. The glomerular nitration rate and renal plasma flow are reduced and filtration fraction rises; there is a marked decrease in urine volume and in excretion of sodium, potassium, and chloride." Although angiotensin ir is the most potent pressor substance known, doses even too small to raise the blood pressure will elicit the renal changes. The promptness of the renal response and its occurrence in adrenalectomized subjects suggest that angiotensin has a direct effect upon the kidney in causing sodium retention. Recent evidence indicates, furthermore, that the renin-angiotensin system may be a major humoral regulator of aldosterone secretion,which would in turn have a bearing upon sodium retention. Jones et al. found the average rate of aldosterone secretion in six pregnant women to be about three times that in six nonpregnant women. This has been confirmed and extended by work thus far published only in abstracts. It is not known that angiotensin mediates this great increase, but it has been suggested that pregnant women may inactivate exogenous angiotensin at an accelerated rate. Abdul-Karim and Assali found smaller pressor responses to single injections of 5 /u.g of synthetic angiotensin n in pregnant than in nonpregnant women, and related the observation to Page's report of a progressive rise