Aust. }. exp. Btot. med. Sci. (1970), 48, pp. 493-500 PERIPHERAL VASCULAR REACTIVITY' TO ANGIOTENSIN AND NORADRENALINE IN PREGNANT AND NON-PREGNANT WOMEN by EUGENIE K. LUMBERS' (From the Department of Human Physiology and Pharmacology, University of Adelaide.) {Received March 25, 1970. Accepted for publication August 26, 1970.). Summary. The hand vascular sensitivity to angiotensiii is reduced in preRtiant women as lumpared to non-prejinant wonu'ii. Sime tht- tiand viiscnlatiirc retains II norinid respoti.sc to iioradrenaline in preKniinl women this rediKticm in sensitivity to anKiotetisin is seltttive. Fiirthennore. tlie rcduttion in sensitivity to the pressor re.spon.se to uiiuio- tensin seen in prvgnaiit womm must, in purt. be due tu a rttluc-tiun in pi-ripheritl vascular sensitivity. Elevations in plasma renin activity, rcnin L-uni'enlrutJun and renin substrate it'vt'Ls are associatttl with the reduction in sensitivity to angiotviutin observed. INTRODUCTION. A reduction in the pressor rc-spon.se to intravenous infu.<iiom of angiotensin i.s characteristic of pathological conditions a.s.sociati'd with lugh circulating levels of renin and presumably angiotensin (Kaplan and Silah, 1964). A .similar associa- tion occurs in pregnancy. Tlie sensitivit)- to intravenous infusions of angiotensin is reduced in pregnant women when the pressor response obtained for a given do.se of angioten.sin is compared to that obtained in non-pregnant women (Chesley, Talledo, Bohler :uid Zuspan, 1965). Elevations in renin levels ami n?nin activit)' in pregnancy are well described ((k-ncst. de Chainplaiii. \'eynit, Hoiieher, Trembliiy. Strong, Koiw and Marc-Aurele. 1965; Helmer iind Jiidson. 1967). Hecently it ha.s been shown (Scroop and Whelan, 1968) that the reduction in pre.ssor sensitivity seen in patients with renovaseular hyperten.sion (Kaplan and Silah, 1964) is associated u-ith a decrease in hand peripheral vascular reactivity. It was. therefore, of some interest to see wliether the decreased pressor respoasivencss of the pregnant woman was also asscK-iated with a reduction in the sensitivity of the peripheral vessels to the constrictor action of the drug. MATEBIAJLS AND METIHODS. Nine precnaiit. female volunteers were stiidie<I. Their ajjes raiiHitl from IH tu 2fi years, all were niilhpiiroiis. more than 32 weeks pregnant and had no tlirieal evidence of toxaemia of pregnancy. Six female vohmteers. who were not pregnant and mil taking oral ctmtratcptive preparati<ms. were aLso studied. Their iiges extendiil over the same ratige us that de.strilied for preRTant women. • National Health ami Medical Research &MineiI Host-griidiiatf Medfc-nl Research Scluilar.