Pressor responses to angiotensin II, phenylephrine, and vasopressin were significantly blunted in pregnant rats compared with virgins, with similar attenuation in both sham and SAD states.
Does sinoaortic denervation alter pressor responses to angiotensin II, phenylephrine, and vasopressin in pregnant rats compared to virgin rats?
Attenuated pressor responses in pregnant rats are primarily due to mechanisms other than augmented arterial baroreflex activity, consistent with a generalized reduction in vascular sensitivity during gestation.
We tested the hypothesis that augmented arterial baroreflex activity contributes to attenuation of pressor responses in intact pregnant animals by comparing changes in blood pressure and heart rate during infusions of angiotensin II, phenylephrine, and vasopressin in chronically instrumented pregnant and virgin rats approximately 5 wk after sinoaortic denervation (SAD) or sham surgery. Baseline mean arterial pressure was significantly lower in pregnant animals in both the sham-operated (pregnant 91.7 +/- 1.7 mmHg, virgin 103.7 +/- 2.5 mmHg) and SAD states (pregnant 107.3 +/- 4.0 mmHg, virgin 114.1 +/- 4.0 mmHg). Pressor responses to all three agents were significantly blunted in pregnant animals compared with similarly treated virgins, with the magnitude of attenuation similar in both sham and SAD states. Heart rate decreased similarly in reflex-intact pregnant and virgin animals during pressor infusions. These findings suggest that attenuated pressor responses in the pregnant rat are due primarily to mechanisms other than augmentation of arterial baroreflex activity and are consistent with a generalized reduction in vascular sensitivity during gestation.
Hines et al. (Mon,) conducted a other in Pregnancy. Sinoaortic denervation (SAD) vs. Sham surgery was evaluated on Changes in blood pressure and heart rate during infusions of angiotensin II, phenylephrine, and vasopressin. Pressor responses to angiotensin II, phenylephrine, and vasopressin were significantly blunted in pregnant rats compared with virgins, with similar attenuation in both sham and SAD states.