Yamasaki M, Lindheimer M D, Umans J G
Department of Medicine, University of Chicago, IL 60637, USA.
Am J Obstet Gynecol. 1996 Sep;175(3 Pt 1):730-6. doi: 10.1053/ob.1996.v175.a73870.
Our purpose was to test the hypothesis that augmented basal and vasodilator agonist-stimulated synthesis of endothelium-derived nitric oxide would blunt vasoconstrictor-induced contraction and enhance relaxation in isolated femoral resistance vessels from pregnant rats.
Potassium chloride-, phenylephrine-, and angiotensin II-induced contraction and acetylcholine-induced relaxation were assessed in small (approximately 240 microns diameter) femoral resistance arteries from gravid and virgin animals studied under isometric conditions; the effects of potassium chloride, phenylephrine, and acetylcholine were also studied in the presence of nitroarginine.
Maximal vasoconstriction was similar in vessels from virgin and pregnant rats, whereas phenylephrine potency was slightly enhanced in vessels from gravid animals. Nitroarginine augmented contraction in both groups but with greater effect on phenylephrine potency and on submaximal potassium chloride contractions in virgins. Acetylcholine-induced relaxation did not differ between groups and was similarly, but only partially, inhibited by nitroarginine.
Pregnancy does not result in vasoconstrictor resistance, increased basal nitric oxide synthesis, or augmented agonist-stimulated endothelium-dependent relaxation in this particular isolated rat microvascular preparation. Further, endothelium-dependent relaxation of these vessels depends only partly on nitric oxide.
我们旨在验证这一假设，即增强基础状态下及血管舒张剂激动剂刺激的内皮源性一氧化氮合成，会减弱血管收缩剂诱导的收缩，并增强妊娠大鼠离体股部阻力血管的舒张。
在等长条件下，评估来自妊娠和未孕动物的小（直径约240微米）股部阻力动脉中氯化钾、去氧肾上腺素和血管紧张素II诱导的收缩以及乙酰胆碱诱导的舒张；还在存在硝基精氨酸的情况下研究了氯化钾、去氧肾上腺素和乙酰胆碱的作用。
未孕和妊娠大鼠血管中的最大血管收缩相似，而妊娠动物血管中去氧肾上腺素的效力略有增强。硝基精氨酸增强了两组的收缩，但对未孕动物去氧肾上腺素效力和次最大氯化钾收缩的影响更大。两组之间乙酰胆碱诱导的舒张没有差异，并且硝基精氨酸对其有相似但仅部分的抑制作用。
在这种特定的离体大鼠微血管制备中，妊娠不会导致血管收缩剂抵抗、基础一氧化氮合成增加或激动剂刺激的内皮依赖性舒张增强。此外，这些血管的内皮依赖性舒张仅部分依赖于一氧化氮。
