Naden R P, Coultrup S, Arant B S, Rosenfeld C R
Am J Physiol. 1985 Jul;249(1 Pt 1):E49-55. doi: 10.1152/ajpendo.1985.249.1.E49.
Reduced vascular responsiveness to infused angiotensin II (ANG II) has been observed during pregnancy. It has been proposed that infusions produce lower circulating concentrations of ANG II in pregnancy, due to an increase in the metabolic clearance rate of ANG II (MCRangii). We have evaluated the MCRangii and the arterial plasma concentrations of ANG II during constant infusions of 1.15 micrograms ANG II/min into chronically instrumented pregnant (n = 6) and nonpregnant (n = 9) sheep. Although the pressor responses were significantly less in the pregnant than in the nonpregnant sheep (17.5 +/- 0.5 vs. 34.9 +/- 3.2 mmHg, P less than 0.001), the values for MCRangii were not different: 56.2 +/- 6.3 ml X min-1 X kg-1 in nonpregnant and 55.9 +/- 4.3 ml X min-1 X kg-1 in pregnant sheep. The steady-state plasma ANG II concentrations during the infusions were slightly less in pregnant than in nonpregnant sheep (388 +/- 36 vs. 454 +/- 36 pg/ml); however, this difference would be responsible for only a 2-mmHg reduction in the pressor response. We conclude that the reduced pressor response to infused ANG II in pregnancy is not due to an increase in MCRangii nor to lower plasma ANG II concentrations.
妊娠期已观察到血管对输注的血管紧张素II（ANG II）的反应性降低。有人提出，由于ANG II的代谢清除率（MCRangii）增加，输注导致妊娠期ANG II的循环浓度降低。我们对6只慢性植入仪器的妊娠绵羊和9只非妊娠绵羊持续输注1.15微克ANG II/分钟，评估了MCRangii和动脉血浆ANG II浓度。虽然妊娠绵羊的升压反应明显低于非妊娠绵羊（17.5±0.5对34.9±3.2 mmHg，P<0.001），但MCRangii的值并无差异：非妊娠绵羊为56.2±6.3 ml·min-1·kg-1，妊娠绵羊为55.9±4.3 ml·min-1·kg-1。输注期间的稳态血浆ANG II浓度，妊娠绵羊略低于非妊娠绵羊（388±36对454±36 pg/ml）；然而，这种差异仅会导致升压反应降低2 mmHg。我们得出结论，妊娠期对输注ANG II的升压反应降低，并非由于MCRangii增加，也不是由于血浆ANG II浓度降低。
