尾加压素Ⅱ对正常及缺血-再灌注离体大鼠心脏的影响
周萍1, 吴胜英1, 于澄钒1, 王华1, 唐朝枢1,2, 林丽3,*, 袁文俊3
1北京大学附属第一医院心血管研究所, 北京 100034;
2北京大学医学部生理和病理生理学系, 北京 100083;
3第二军医大学基础医学部生理学教研室, 上海 200433
摘要: 本工作在正常Langendorff灌流与缺血-再灌注(停灌20 min-复灌20 min)离体大鼠心脏模型, 观察尾加压素Ⅱ (urotensin II, UⅡ)对冠脉流量、心功能和心肌代谢的影响以及心肌UⅡ受体的功能, 以探讨UⅡ的心脏效应。对正常心脏给予0.1、1和10 nmol/L UⅡ各5 min, 然后换洗5 min, 对停灌缺血-再灌注心脏再灌注期给予1或10 nmol/L UⅡ。监测心率、左室内压、左室内压升降的最大变化率等心功能指标, 计算冠脉流量, 测定冠脉流出液中总蛋白和肌红蛋白含量以及乳酸脱氢酶(LDH)活性, 灌流结束后测定心肌丙二醛(MDA)含量和质膜UⅡ结合位点(放射性配基结合法)。结果如下: (1)正常心脏灌流UⅡ后, 冠脉流量和心功能呈浓度依赖下降, 换洗后没有完全恢复。心肌蛋白、肌红蛋白和LDH漏出随UⅡ浓度的增加而增加, 换洗后迅速减少。UⅡ组心肌MDA含量与对照组差异无显著性。(2)缺血-再灌注后冠脉流量显著减少, 心功能显著抑制, 再灌注期心肌蛋白、肌红蛋白和LDH明显漏出; 给予UⅡ后, 上述变化增强, 且高浓度组更强, 与对照组差异有显著性(P<0.01), 再灌注后心肌MDA含量亦显著高于对照(P<0.01)。 (3) 缺血-再灌注心肌质膜UⅡ受体的Bmax显著高于正常对照心肌(14.65±1.78 vs 20.53±1.98 fmol/mg Pr, P<0.01), Kd值变化无统计学意义。上述结果表明, 在正常灌流的离体大鼠心脏, UⅡ使冠脉流量减少、心功能抑制, 并可造成心肌损伤; 在缺血-再灌注心脏, UⅡ受体上调, UⅡ加重冠脉流量减少、心功能抑制以及心肌损伤。
关键词: 病理学; 尾加压素Ⅱ; 心脏离体灌流; 缺血-再灌注; 大鼠
中图分类号: R331.31
Effects of
urotensin Ⅱ on isolated rat hearts under normal perfusion and
ischemia-reperfusion
ZHOU Ping1, WU Sheng-Ying1, YU Cheng-Fan1, WANG Hua1, TANG Chao-Shu1,2, LIN Li3,*, YUAN Wen-Jun3
1Cardiovascular
Institute,
2Department
of Physiology and Pathophysiology,
3Department
of Physiology,
Shanghai 200433
Abstract: To shed light on cardiac effects of the potent vasoconstrictive peptide urotensin Ⅱ (UⅡ), Langendorff-perfused isolated rat hearts were consecutively perfused with 0.1, 1 and 10 nmol/L UⅡ, for 5 min each dose, followed by 5-min washout. Moreover, isolated hearts subjected to 20-min global no-flow ischemia were reperfused with UⅡ (1 or 10 nmol/L) for 20 min. Heart function parameters including heart rate, left ventricular pressure and dP/dt were monitored; content of protein and myoglobin, and activity of lactate dehydrogenase (LDH) in coronary effluent were determined; malondialdehyde (MDA) in myocardium and ［125］-UⅡ binding sites in plasma membrane were measured after the completion of perfusion. The results showed that: (1) In normal rat hearts, the coronary flow was decreased and the heart function was suppressed by UⅡ dose-dependently, and these changes were not abolished by washout. The leakage of cardiac protein, myoglobin and LDH increased as the increment of UⅡ, while diminished rapidly after washout. In contrast, MDA content in UⅡ-treated myocardium was not statistically different from that in normal myocardium. (2) Ischemia-reperfusion caused a significant decrease in coronary flow, suppression of heart function, and leakage of protein and LDH. In UⅡ-reperfused hearts, all these disorders were significantly aggravated and myocardial MDA content significantly increased (P<0.01), to a greater extent in the presence of higher dose of UⅡ. (3) The maximal binding capacity (Bmax) of UⅡ receptors in plasma membrane from ischemia-reperfusion myocardium increased significantly as compared with that of normal myocardium (20.53±1.98 vs 14.65±1.78 fmol/mg Pr, P<0.01), while Kd remained unchanged. These results indicated that, UⅡ caused injury to the isolated rat hearts under normal perfusion, and worsened the injury of the hearts under ischemia-reperfusion, in which UⅡ receptors were up-regulated.
Key words: pathology; urotensin II; isolated heart perfusion; ischemia-reperfusion; rat