Assali N S, Nuwayhid B, Brinkman C R, Tabsh K, Erkkola R, Ushioda E
Am J Obstet Gynecol. 1981 Dec 15;141(8):873-84. doi: 10.1016/s0002-9378(16)32678-3.
Pregnancy alters the autonomic control of the peripheral circulation. Present in vivo and in vitro studies were designed to investigate the mechanisms of these alterations. In the in vivo studies, pelvic and systemic circulatory responses to intra-arterial and intravenous injections of agonists were monitored in unanesthetized pregnant and nonpregnant ewes. In in vitro studies, a comparison was made of responses to transmural nerve stimulation (TNS) and to norepinephrine (NE) of different blood vessels obtained from pregnant and nonpregnant ewes. The results were the following: (1) Pelvic vascular response to all vasoactive stimuli was considerably more depressed during pregnancy than was systemic circulatory response. (2) In vitro reactivity to alpha-adrenergic stimulation with NE of different blood vessels obtained from pregnant animals was similar to that of vessels from nonpregnant animals. (3) The response to TNS of blood vessels obtained from pregnant ewes was less than that of vessels from nonpregnant ewes. The conclusions were that (a) probably largely related to dilution of a given dose of the stimulus in the greater blood volume and flow; and (b) the increased neurogenic tone of the peripheral circulation during pregnancy is most likely related to increased nerve firing rather than neural density in the vessel walls.
怀孕会改变外周循环的自主控制。目前的体内和体外研究旨在探究这些改变的机制。在体内研究中，监测了未麻醉的怀孕母羊和未怀孕母羊对动脉内和静脉内注射激动剂的盆腔和全身循环反应。在体外研究中，比较了从怀孕母羊和未怀孕母羊获取的不同血管对跨壁神经刺激（TNS）和去甲肾上腺素（NE）的反应。结果如下：（1）怀孕期间，盆腔血管对所有血管活性刺激的反应比全身循环反应受到的抑制程度要大得多。（2）从怀孕动物获取的不同血管对NE的α-肾上腺素能刺激的体外反应性与从未怀孕动物获取的血管相似。（3）从怀孕母羊获取的血管对TNS的反应小于从未怀孕母羊获取的血管。结论是：（a）这可能很大程度上与给定剂量的刺激在更大的血容量和血流中被稀释有关；（b）怀孕期间外周循环中神经源性张力增加最可能与神经放电增加有关，而非血管壁中神经密度增加。
