Gutterman D D, Morgan D A
Veterans Affairs Medical Center, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
Basic Res Cardiol. 1995 Jul-Aug;90(4):348-55. doi: 10.1007/BF00797913.
In vivo studies have shown that sympathetic nerve stimulation improves the transmural distribution of myocardial perfusion by increasing the endocardial/epicardial flow ratio; however, the mechanism of this effect is unknown. During nerve stimulation both norepinephrine (NE) and neuropeptide Y (NPY) are released, either or both of which may exert vasoconstrictor effects. The present studies were performed to examine the effects of these two cotransmitters on the transmural distribution of myocardial perfusion in a canine model. In anesthetized open-chest dogs, during maximal coronary vasodilation with intracoronary adenosine, both neuropeptide Y (29.7 micrograms/min) and norepinephrine (0.5-2.0 micrograms/min) reduced myocardial perfusion to a greater extent in the epicardium than in the subendocardium. The endo/epi ratio with adenosine alone was 1.11 +/- 0.02. Norepinephrine increased this by 80%, neuropeptide Y by 20%, and the combination of the two by 76% (P < 0.05 for all three vs. adenosine). Neuropeptide Y alone constricted the coronary vasculature but did not alter transmural flow. Thus neuropeptide Y preferentially reduces myocardial perfusion in the epicardium. We speculate that neuronally released neuropeptide Y contributes importantly to the transmural distribution of myocardial perfusion during sympathetic nerve stimulation.
体内研究表明，交感神经刺激通过增加心内膜/心外膜血流比值来改善心肌灌注的透壁分布；然而，这种效应的机制尚不清楚。在神经刺激过程中，去甲肾上腺素（NE）和神经肽Y（NPY）都会释放，其中任何一种或两种都可能发挥血管收缩作用。本研究旨在检测这两种共递质对犬模型中心肌灌注透壁分布的影响。在麻醉开胸犬中，在冠状动脉内注射腺苷使冠状动脉最大程度扩张期间，神经肽Y（29.7微克/分钟）和去甲肾上腺素（0.5 - 2.0微克/分钟）使心外膜心肌灌注减少的程度均大于心内膜下心肌。单独使用腺苷时的内膜/外膜比值为1.11±0.02。去甲肾上腺素使该比值增加80%，神经肽Y使该比值增加20%，两者联合使该比值增加76%（三者与腺苷相比，P均<0.05）。单独使用神经肽Y可使冠状动脉血管收缩，但不改变透壁血流。因此，神经肽Y优先减少心外膜的心肌灌注。我们推测，神经释放的神经肽Y在交感神经刺激期间对心肌灌注的透壁分布起重要作用。
