Brunner F
Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Austria.
J Mol Cell Cardiol. 1995 Sep;27(9):1953-63. doi: 10.1016/0022-2828(95)90017-9.
The purpose of this study was to compare coronary and interstitial endothelin-1 (ET-1) levels in perfused rat hearts under several experimental conditions, because the cardiac tissue concentration of ET-1 is not clear. Hearts were perfused in an upside-down position with a colloid-free buffer at a constant flow rate of 9 ml/min/g heart wet weight, and immunoreactive ET-1 was determined in timed collections of coronary effluent and interstitial transudate produced by the ventricles and appearing on their surface. Basal ET-1 release into effluent was 0.26 +/- 0.007 pg/min/g, and 0.005 +/- 0.0012 pg/min/g in transudate. Basal ET-1 concentration was 0.11 +/- 0.005 pg/ml (transudate) and 0.03 +/- 0.002 pg/ml (effluent), indicating four-fold higher transudate than effluent levels (P < 0.05). Following perfusion of hearts with collagenase to remove endothelial cells, ET-1 release into effluent was reduced to one-third and completely abolished in transudate, indicating that the peptide originated from the vascular endothelium. Perfusion of hearts with angiotensin II (0.1 mumol/l) or thrombin (5 U/ml) increased coronary perfusion pressure and ET-1 secretion, but little affected the transudate/effluent ET-1 concentration ratio (5.5 and 3.2, respectively). When coronary flow was reduced to ischaemic level (1 ml/min/g over several hours), ET-1 secretion rates into effluent were decreased by 55-65%, but increased three- to four-fold on reperfusion at normal flow (P < 0.05). The ET-1 concentrations in both fluids were still always below 1 pg/ml. No change in coronary perfusion pressure compared to time-matched normoxic controls was observed. In the presence of the ET-1 converting enzyme inhibitor, phosphoramidon (1.7 mumol/l), ischaemia-induced increases of ET-1 secretion were attenuated, and this was accompanied by a time-dependent rise in coronary perfusion pressure up to 60% (P < 0.05). These are the first measurements of endogenous cardiac tissue ET-1 levels; they do not support a vasoconstrictor (pro-ischaemic) action of endogenous ET-1 in rat hearts following ischaemia/reperfusion, but rather point to a possible vasodilator role of the peptide under these conditions.
本研究的目的是比较在几种实验条件下灌注大鼠心脏中冠状动脉和间质内皮素 -1（ET-1）的水平，因为心脏组织中ET-1的浓度尚不清楚。心脏以倒置位置用无胶体缓冲液以9 ml/min/g心脏湿重的恒定流速进行灌注，并在定时收集的冠状动脉流出液和由心室产生并出现在其表面的间质渗出液中测定免疫反应性ET-1。流出液中基础ET-1释放量为0.26±0.007 pg/min/g，渗出液中为0.005±0.0012 pg/min/g。基础ET-1浓度在渗出液中为0.11±0.005 pg/ml，在流出液中为0.03±0.002 pg/ml，表明渗出液水平比流出液高四倍（P<0.05）。在用胶原酶灌注心脏以去除内皮细胞后，流出液中ET-1释放量降至三分之一，渗出液中则完全消失，表明该肽起源于血管内皮。用血管紧张素II（0.1 μmol/l）或凝血酶（5 U/ml）灌注心脏会增加冠状动脉灌注压和ET-1分泌，但对渗出液/流出液ET-1浓度比影响不大（分别为5.5和3.2）。当冠状动脉血流降至缺血水平（数小时内1 ml/min/g）时，流出液中ET-1分泌率降低55 - 65%，但在恢复正常血流再灌注时增加三到四倍（P<0.05）。两种液体中的ET-1浓度始终低于1 pg/ml。与时间匹配的常氧对照组相比，未观察到冠状动脉灌注压有变化。在存在ET-1转换酶抑制剂磷酰胺（1.7 μmol/l）的情况下，缺血诱导的ET-1分泌增加被减弱，同时冠状动脉灌注压随时间依赖性升高高达60%（P<0.05）。这些是首次对内源性心脏组织ET-1水平的测量；它们不支持内源性ET-1在大鼠心脏缺血/再灌注后具有血管收缩（促缺血）作用，而是指出在这些条件下该肽可能具有血管舒张作用。
