Clark K E, Austin J E, Stys S J
Am J Obstet Gynecol. 1982 Nov 1;144(5):497-502. doi: 10.1016/0002-9378(82)90216-2.
Vasoactive intestinal polypeptide has been localized in the uterine vasculature, uterine smooth muscle and the placenta of several species. Vasoactive intestinal polypeptide is a potent uterine vasodilator in nonpregnant sheep and also abolishes spontaneous uterine contractile activity, but the effects of this polypeptide on the uterine vasculature of the pregnant animal is currently unknown. The present experiments were performed in seven late-term pregnant sheep which were chronically catheterized to evaluate the uterine vascular effects of vasoactive intestinal polypeptide. An intra-arterial catheter was placed in a branch of the main uterine artery to allow administration of vasoactive intestinal polypeptide directly into the uterine vasculature. Uterine blood flow was continuously monitored via an electromagnetic flow transducer on both main uterine arteries. Vasoactive intestinal polypeptide infused at the rate of 1 to 30 micrograms/min produced dose-related reductions in uterine blood flow (33% +/- 9% at 30 micrograms/min). This decrease was due to a reduction in systemic arterial blood pressure, since calculated resistance in the uterine vasculature that received the vasoactive intestinal polypeptide did not change significantly. In addition, the contralateral uterine vasculature that did not receive direct intra-arterial infusions of vasoactive intestinal polypeptide showed identical changes. These data suggest that vasoactive intestinal polypeptide produces peripheral vasodilation at doses which have very little uterine effect locally. These data can be interpreted to mean either that high local endogenous production of vasoactive intestinal polypeptide prevents exogenously administered vasoactive intestinal polypeptide from exerting its vascular effects, or that vasoactive intestinal polypeptide is a very weak uterine vasodilator in pregnant ewes. The clarification of these possibilities will require further experimentation.
血管活性肠肽已在几种物种的子宫血管、子宫平滑肌和胎盘中定位。血管活性肠肽在未怀孕的绵羊中是一种强力的子宫血管舒张剂，还能消除子宫的自发收缩活动，但这种多肽对怀孕动物子宫血管的影响目前尚不清楚。本实验对7只晚期怀孕绵羊进行，这些绵羊长期插管以评估血管活性肠肽对子宫血管的影响。将一根动脉内导管置于子宫主动脉的一个分支中，以便将血管活性肠肽直接注入子宫血管。通过两个子宫主动脉上的电磁流量传感器持续监测子宫血流量。以1至30微克/分钟的速率注入血管活性肠肽会导致子宫血流量出现剂量相关的减少（30微克/分钟时为33%±9%）。这种减少是由于全身动脉血压降低所致，因为接受血管活性肠肽的子宫血管中的计算阻力没有显著变化。此外，未接受血管活性肠肽动脉内直接输注的对侧子宫血管也出现了相同的变化。这些数据表明，血管活性肠肽在局部对子宫几乎没有影响的剂量下会产生外周血管舒张。这些数据可以解释为，要么是血管活性肠肽的高局部内源性产生阻止了外源性给予的血管活性肠肽发挥其血管作用，要么是血管活性肠肽在怀孕母羊中是一种非常弱的子宫血管舒张剂。要澄清这些可能性还需要进一步的实验。
