Hines T, Barron W M
Department of Obstetrics and Gynecology, University of Chicago, Illinois 60637.
Am J Physiol. 1992 Jun;262(6 Pt 2):R1100-5. doi: 10.1152/ajpregu.1992.262.6.R1100.
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.
我们通过比较在慢性植入仪器的妊娠大鼠和未孕大鼠中，在大约5周的主动脉去神经支配（SAD）或假手术后，输注血管紧张素II、去氧肾上腺素和血管加压素期间的血压和心率变化，来检验增强的动脉压力反射活动有助于减弱完整妊娠动物的升压反应这一假设。在假手术组（妊娠大鼠平均动脉压91.7±1.7 mmHg，未孕大鼠103.7±2.5 mmHg）和SAD组（妊娠大鼠107.3±4.0 mmHg，未孕大鼠114.1±4.0 mmHg）中，妊娠动物的基线平均动脉压均显著较低。与同样处理的未孕动物相比，妊娠动物对所有三种药物的升压反应均显著减弱，在假手术组和SAD组中减弱幅度相似。在升压输注期间，有完整压力反射的妊娠和未孕动物的心率下降情况相似。这些发现表明，妊娠大鼠升压反应减弱主要是由于动脉压力反射活动增强以外的机制，并且与妊娠期血管敏感性普遍降低一致。
