Baroreflex control of sympathetic outflow in pregnant rats: effects of captopril.
Baroreflex control of sympathetic outflow in pregnant rats: effects of captopril.
复制标题
妊娠大鼠交感神经流出的压力反射控制：卡托普利的作用。
DOI：
10.1152/ajpregu.1990.258.6.r1417
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Heesch,CM
中科院分区：
文献类型：
--
作者：
Crandall,ME;Heesch,CM
在氯醛糖麻醉的未孕（NP）和近孕（P）大鼠中比较了肾交感神经活动（RSNA）的动脉压力反射控制。通过记录由于平均动脉压（MAP）[静脉注射苯巴比妥和硝普钠（NTP）]升高和降低引起的RSNA反射变化（表示为基线的百分比），获得压力反射曲线。比较压力反射曲线的斜率、中点（EP 50）和阈值压力。妊娠动物的基线MAP显著较低（P = 96 +/- 3 vs. NP = 113 +/- 5 mmHg）。妊娠动物的压力反射曲线也具有显著较低的阈值（P = 95 +/- 3 vs. NP = 110 +/- 5 mmHg）和中点值（P = 105 +/- 4 vs. NP = 119 +/- 5 mmHg）。压力感受器卸载的反应在妊娠动物中减弱，如压力感受器反射曲线的NTP部分的斜率的降低所示（P = 0.95 +/- 0.17 vs. NP = 1.61 +/- 0.29%神经活动/mmHg）。还检查了对血管紧张素转换酶与卡托普利（2 mg/kg iv）的阻断的反应。在未妊娠或妊娠动物中，对照、卡托普利和恢复期压力感受性反射曲线之间的EP 50或斜率无差异。而给药后，孕鼠的MAP下降幅度较大，而RSNA则升高至相同水平。因此，妊娠导致压力感受器反射功能曲线向较低的工作压力范围移动。此外，妊娠大鼠表现出受损的能力，增加交感神经流出超过基线值，以响应一个兴奋的挑战。
Arterial baroreflex control of renal sympathetic nerve activity (RSNA) was compared in nonpregnant (NP) and near-term pregnant (P) chloralose-anesthetized rats. Baroreflex curves were obtained by recording reflex changes in RSNA (expressed as a percent of base line) due to increases and decreases in mean arterial pressure (MAP) [intravenous phenylephrine and nitroprusside (NTP)]. The slope, midpoint (EP50), and threshold pressures of the baroreflex curves were compared. Base-line MAP was significantly lower in the pregnant animals (P = 96 +/- 3 vs. NP = 113 +/- 5 mmHg). The baroreflex curves of pregnant animals also had significantly lower threshold (P = 95 +/- 3 vs. NP = 110 +/- 5 mmHg) and midpoint values (P = 105 +/- 4 vs. NP = 119 +/- 5 mmHg). The response to unloading the baroreceptors was attenuated in the pregnant animals as indicated by a decrease in slope of the NTP portion of the baroreflex curve (P = 0.95 +/- 0.17 vs. NP = 1.61 +/- 0.29% nerve activity/mmHg). Responses to blockade of angiotensin-converting enzyme with captopril (2 mg/kg iv) were also examined. There were no differences in EP50 or slope among the control, captopril, and recovery baroreflex curves within either the nonpregnant or pregnant animals. However, after captopril, MAP decreased to a greater extent in the pregnant rats, yet RSNA increased to the same level for the two groups. Thus pregnancy results in a leftward shift of the baroreflex function curve toward a lower operating pressure range. In addition, pregnant rats demonstrated an impaired ability to increase sympathetic outflow above base-line values in response to a hypotensive challenge.