Erkkola R, Tabsh K, Ushioda E, Nuwayhid B, Brinkman C R, Assali N S
Am J Obstet Gynecol. 1981 Nov 15;141(6):599-607. doi: 10.1016/s0002-9378(15)33297-x.
The responses of different parts of the pelvic vascular bed to beta-adrenergic and cholinergic receptor stimulation were studied in chronically instrumented, unanesthetized pregnant and nonpregnant sheep. Isoproterenol and acetylcholine were administered intra-arterially in progressively increasing bolus injections, and dose-response curves were constructed for changes in blood flows, arterial pressure, and heart rate. Response to beta-adrenergic and cholinergic stimulation was measured before and after the agents reached the central circulation. In addition, data were obtained from the same animals before and after pharmacologic cardiac denervation. Results show: (1) Stimulation of beta-adrenergic and cholinergic receptors produced active vasodilatation in extrauterine vascular beds with minor changes in uterine blood flow of the pregnant horn; (2) the changes in uterine flow observed during beta-adrenergic and cholinergic stimulation were probably secondary and related to a shift of blood from the uterus to other vascular beds that were actively dilated; (3) the response of the pregnant animal to any given dose of the autonomic agonist was strikingly smaller to that of the nonpregnant animal. A number of physiologic factors peculiar to pregnancy may contribute to this difference; among these are: (1) dilution factor related to the greater volume flow; (2) near-maximal dilatation of some blood vessels and the presence of the two resistance system of placental circulation, and (3) the effect of progesterone on the vascular smooth muscle.
在长期植入仪器、未麻醉的怀孕和未怀孕绵羊中，研究了盆腔血管床不同部位对β-肾上腺素能和胆碱能受体刺激的反应。以逐渐增加的推注剂量动脉内注射异丙肾上腺素和乙酰胆碱，并构建血流、动脉压和心率变化的剂量反应曲线。在药物到达体循环之前和之后测量对β-肾上腺素能和胆碱能刺激的反应。此外，从同一动物在药物性心脏去神经支配之前和之后获取数据。结果显示：(1) 刺激β-肾上腺素能和胆碱能受体在子宫外血管床产生主动血管舒张，怀孕侧子宫血流量变化较小；(2) 在β-肾上腺素能和胆碱能刺激期间观察到的子宫血流量变化可能是继发性的，并且与血液从子宫转移到其他主动扩张的血管床有关；(3) 怀孕动物对任何给定剂量的自主激动剂的反应明显小于未怀孕动物。许多妊娠特有的生理因素可能导致这种差异；其中包括：(1) 与更大流量相关的稀释因子；(2) 一些血管接近最大扩张以及胎盘循环存在两个阻力系统，以及(3) 孕酮对血管平滑肌的作用。
