Bund S J, Oldham A A, Heagerty A M
Department of Medicine, University Hospital of South Manchester, West Didsbury, United Kingdom.
Cardiovasc Res. 1994 May;28(5):695-9. doi: 10.1093/cvr/28.5.695.
The aim was to determine whether regional differences in arterial responses to vasoconstrictor and vasorelaxant agonists exist within the minipig coronary vasculature.
Hearts were obtained from miniature pigs (20-40 kg) immediately after death. First and third order arterial branches of the left anterior descending artery were dissected from within the subepicardium and mounted as ring preparations in a small vessel myograph for measurement of isometric tension under standardised conditions. Contractile responses to acetylcholine, noradrenaline, and U46619, and the relaxation responses to noradrenaline, bradykinin, and substance P were measured. Arterial tone was increased with KCl or acetylcholine prior to addition of vasodilator agonists.
First order branches were more sensitive to the constrictor influence of acetylcholine than third order branches [pD2 values 6.42(SEM 0.07), n = 13, and 6.26(0.07), n = 13, for first and third order respectively, p < 0.05]. U46619 did not induce contractile responses in arteries less than 210 microns in diameter. Noradrenaline only induced small contractile responses in the presence of propranolol following removal of the endothelium. In arteries preconstricted with 40 mM KCl, noradrenaline induced relaxation which was inhibited by propranolol and was uninfluenced by arterial calibre. In the presence of propranolol, noradrenaline-mediated relaxations of acetylcholine-preconstricted arteries were endothelium dependent and alpha 2 adrenoceptor mediated, and greater in first order than in third order branches [58(5)%, n = 9, and 26(8)%, n = 9, for first and third order branches respectively, p < 0.05]. Relaxations mediated by bradykinin and substance P were not influenced significantly by arterial calibre but were greater in arteries preconstricted with acetylcholine than with KCl.
In isolated minipig coronary arteries the vasoconstrictor responses to acetylcholine and U46619, and the endothelium dependent, noradrenaline mediated relaxations, differ according to the branching order studied. These data provide further evidence for a regional heterogeneity of vascular responses in the porcine coronary vasculature.
确定小型猪冠状动脉血管系统内对血管收缩剂和血管舒张剂激动剂的动脉反应是否存在区域差异。
在小型猪（20 - 40千克）死后立即获取心脏。从心外膜下解剖出左前降支的一级和三级动脉分支，并制成环状标本，置于小型血管肌动描记器中，在标准化条件下测量等长张力。测量对乙酰胆碱、去甲肾上腺素和U46619的收缩反应，以及对去甲肾上腺素、缓激肽和P物质的舒张反应。在添加血管舒张剂激动剂之前，用氯化钾或乙酰胆碱增加动脉张力。
一级分支对乙酰胆碱的收缩作用比三级分支更敏感[一级和三级分支的pD2值分别为6.42（标准误0.07），n = 13，和6.26（0.07），n = 13，p < 0.05]。U46619对直径小于210微米的动脉未诱导出收缩反应。去除内皮后，在普萘洛尔存在的情况下，去甲肾上腺素仅诱导出小的收缩反应。在用40 mM氯化钾预收缩的动脉中，去甲肾上腺素诱导的舒张被普萘洛尔抑制，且不受动脉管径影响。在普萘洛尔存在的情况下，去甲肾上腺素介导的乙酰胆碱预收缩动脉的舒张是内皮依赖性的，由α2肾上腺素能受体介导，且一级分支比三级分支更明显[一级和三级分支分别为58（5）%，n = 9，和26（8）%，n = 9，p < 0.05]。缓激肽和P物质介导的舒张不受动脉管径的显著影响，但在乙酰胆碱预收缩的动脉中比在氯化钾预收缩的动脉中更明显。
在分离的小型猪冠状动脉中，对乙酰胆碱和U46619的血管收缩反应以及内皮依赖性、去甲肾上腺素介导的舒张反应，根据所研究的分支顺序而有所不同。这些数据为猪冠状动脉血管系统中血管反应的区域异质性提供了进一步的证据。
