Lamping K G, Chilian W M, Eastham C L, Marcus M L
Department of Internal Medicine, College of Medicine, University of Iowa, Iowa City 52242.
Microvasc Res. 1992 May;43(3):294-307. doi: 10.1016/0026-2862(92)90027-m.
The objectives of the present study were first, to determine the coronary microvascular response to vagal stimulation and to compare it to exogenously administered acetylcholine, and second, to determine the microvascular response to larger doses of acetylcholine which preferentially increase subendocardial blood flow. In anesthetized cats and dogs, the left ventricular epicardial vasculature was visualized in mid-diastole with stroboscopic epi-illumination. Myocardial perfusion was measured with the radioactive microsphere technique. In cats microvascular diameters were measured at control and following bilateral vagal nerve stimulation (5-30 Hz) or left atrial infusion of acetylcholine (0.4-1.0 micrograms/kg/min). Aortic pressure and heart rate (A-V-sequential pacing) were maintained constant. Vagal stimulation (n = 13) increased myocardial perfusion by 25 +/- 9% (control: 161 +/- 17 ml/min x 100 g). Acetylcholine (n = 13) produced a similar increase in myocardial flow (control: 185 +/- 16 ml/min x 100 g, 30 +/- 9%). Both vagal stimulation and acetylcholine dilated all size arteries and arterioles (51-410 microns; 5 +/- 1% and 11 +/- 2%, respectively). In dogs intracoronary administration of acetylcholine (10 micrograms/min) that increased myocardial flow twofold (control: 129 +/- 7 ml/min x 100 g; 10 micrograms/min: 263 +/- 26 ml/min x 100 g) and increased the endo/epi flow ratio also dilated all vessel sizes. In conclusion, vagal stimulation and exogenously administered acetylcholine produce similar effects on the coronary microcirculation and dilate all size classes of arteries and arterioles in a similar manner. Intracoronary infusion of acetylcholine which preferentially increases subendocardial blood flow also dilates all size classes of microvessels. Thus, the ability of acetylcholine to preferentially increase subendocardial blood flow cannot be explained by a selective dilation of a particular size class of arterioles. These data suggest that neurally released acetylcholine can diffuse to the endothelial layer to release vasodilator substances in vivo.
本研究的目的，其一，是确定冠状动脉微血管对迷走神经刺激的反应，并将其与外源性给予的乙酰胆碱相比较；其二，是确定微血管对较大剂量乙酰胆碱的反应，该剂量会优先增加心内膜下血流量。在麻醉的猫和狗身上，用频闪灯心外膜照明在舒张中期观察左心室心外膜血管系统。用放射性微球技术测量心肌灌注。在猫身上，于对照时以及双侧迷走神经刺激（5 - 30赫兹）或左心房输注乙酰胆碱（0.4 - 1.0微克/千克/分钟）后测量微血管直径。维持主动脉压和心率（房室顺序起搏）恒定。迷走神经刺激（n = 13）使心肌灌注增加25±9%（对照：161±17毫升/分钟×100克）。乙酰胆碱（n = 13）使心肌血流量产生类似增加（对照：185±16毫升/分钟×100克，30±9%）。迷走神经刺激和乙酰胆碱均使所有大小的动脉和小动脉扩张（51 - 410微米；分别为5±1%和11±2%）。在狗身上，冠状动脉内给予乙酰胆碱（10微克/分钟）使心肌血流量增加两倍（对照：129±7毫升/分钟×100克；10微克/分钟：263±26毫升/分钟×100克）并增加内膜/外膜血流比值，同时也使所有血管大小扩张。总之，迷走神经刺激和外源性给予的乙酰胆碱对冠状动脉微循环产生类似作用，并以类似方式使所有大小类别的动脉和小动脉扩张。冠状动脉内输注优先增加心内膜下血流量的乙酰胆碱也使所有大小类别的微血管扩张。因此，乙酰胆碱优先增加心内膜下血流量的能力不能用特定大小类别的小动脉的选择性扩张来解释。这些数据表明，神经释放的乙酰胆碱可在体内扩散至内皮细胞层以释放血管舒张物质。
