Blood Pressure Effects of Angiotensin II and Vasopressin in Conscious Pregnant Normotensive and Spontaneously Hypertensive Rats

Abstract

In order to determine vascular reactivity to vasoconstrictor agents during pregnancy in hypertensive animals, dose-response curves to the pressor effect of angiotensin II (AII) and arginine⁸-vasopressin (AVP) were measured in unrestrained, conscious and catheterized normotensive, Sprague-Dawley (SD), Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats at the end of pregnancy and in non-pregnant animals. At the end of gestation, the sensitivity to both agents was decreased by a factor varying from 1.3 to 2.1 in the three strains of rats. The blood pressure reached by each dose of AII and AVP was lower during gestation in the three strains. This was not the result of lower blood pressure in pregnant rats, since pregnant normotensive SD rats did not show any decrease of control blood pressure and their response to each dose of both agents was also reduced. Furthermore, the sensitivity to both vasoconstrictors was decreased in pregnant rats of each strain by comparison to non-pregnant rats. In conclusion, vascular reactivity to both All and AVP decreases during gestation.