O'Hagan K P, Skogg K A, Stevenson J B
Department of Physiology, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois 60515, USA.
Am J Physiol Heart Circ Physiol. 2001 May;280(5):H1996-2005. doi: 10.1152/ajpheart.2001.280.5.H1996.
The role of ANG II in the arterial baroreflex control of renal sympathetic nerve activity (RSNA) in eight term-pregnant (P) and eight nonpregnant (NP) conscious rabbits was assessed using sequential intracerebroventricular and intravenous infusions of losartan, an AT1 receptor antagonist. The blood pressure (BP)-RSNA relationship was generated by sequential inflations of aortic and vena caval perivascular occluders. Pregnant rabbits exhibited a lower maximal RSNA reflex gain (-44%) that was primarily due to a reduction in the maximal sympathetic response to hypotension (P, 248 +/- 20% vs. NP, 357 +/- 41% of rest RSNA, P < 0.05). Intracerebroventricular losartan decreased resting BP in P (by 9 +/- 3 mmHg, P < 0.05) but not NP rabbits, and had no effect on the RSNA baroreflex in either group. Subsequent intravenous losartan decreased resting BP in NP and further decreased BP in P rabbits, but had no significant effect on the maximal RSNA reflex gain. ANG II may have an enhanced role in the tonic support of BP in pregnancy, but does not mediate the gestational depression in the arterial baroreflex control of RSNA in rabbits.
利用AT1受体拮抗剂氯沙坦，通过依次进行脑室内和静脉内输注，评估了八只足月妊娠（P）和八只非妊娠（NP）清醒家兔中血管紧张素II（ANG II）在肾交感神经活动（RSNA）的动脉压力反射控制中的作用。通过依次充气主动脉和腔静脉血管周围阻塞器来建立血压（BP）-RSNA关系。妊娠家兔的最大RSNA反射增益较低（-44%），这主要是由于对低血压的最大交感反应降低所致（P组，相对于静息RSNA的248±20%，NP组为357±41%，P<0.05）。脑室内注射氯沙坦可降低P组家兔的静息血压（降低9±3 mmHg，P<0.05），但对NP组家兔无此作用，且对两组的RSNA压力反射均无影响。随后静脉注射氯沙坦可降低NP组家兔的静息血压，并使P组家兔的血压进一步降低，但对最大RSNA反射增益无显著影响。ANG II可能在孕期血压的紧张性支持中发挥增强作用，但并不介导家兔动脉压力反射对RSNA控制中的妊娠性抑制。
