Baroreflex Control of Sympathetic Nerve Activity in Hypertensive Pregnant Rats with Reduced Uterine Perfusion

Abstract

OBJECTIVE: Baroreflex sensitivity is reduced in women with preeclampsia. The aim of this study was to determine whether baroreflex control of renal sympathetic nerve activity (RSNA) is altered in pregnant rats with reduced uterine perfusion (a model of human preeclampsia). METHODS: Uterine perfusion was reduced in the third trimester by clipping the distal aorta and uterine branches of the ovarian arteries. RSNA baroreflex parameters were compared at term gestation in rats with reduced uterine perfusion (n = 12), in normal pregnant rats (n = 14) and in nonpregnant rats (n = 14). RESULTS: Reduced perfusion rats were hypertensive (123.6 +/- 2.3 mm Hg), and normal pregnant rats were hypotensive (97.7 +/- 2.2 mm Hg), compared with controls. In rats with reduced perfusion, the baroreflex was shifted to a higher set-point, and maximum and minimum RSNA were increased compared with normal pregnant rats. CONCLUSION: The blunted baroreflex gain of normal pregnancy is maintained in rats with reduced uterine perfusion, but a hypertensive shift in baroreflex function exists in this rat model that is associated with a reversal of the reflex maximum and minimum RSNA observed in normal pregnancy.