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目的研究根皮素对狗冠状动脉舒张特征的影响及其机制。方法制备狗冠状动脉血管环,固定于盛有K-H液的恒温肌槽内,并观察等长时血管张力的变化。结果 10μmol·L-1或30μmol·L-1L根皮素使KCl及无钙K-H液中CaCl2量效曲线明显右移,使血管环敏感性和最大收缩反应明显降低。30μmol·L-1根皮素在50 mmol·L-1KCl预收缩的离体冠脉血管环产生一个明显的急性舒张,加入Nω-L-硝基精氨酸1×10-4mol·L-1、普萘洛尔1×10-5mol·L-1、亚甲蓝1×10-5mol·L-1、二硝酸异山梨醇酯(吲哚美辛)1×10-5mol·L-1及去内皮细胞后,根皮素的急性舒张血管作用不受影响。结论根皮素在离体冠脉血管环的舒张效应主要是通过抑制电压依赖性钙通道实现的。根皮素的这种舒张效应与NO、内皮、β肾上腺素受体和前列腺素类皆无关。
Objective To study the effect of phloretin on diastolic characteristics of coronary artery in dogs and its mechanism. Methods Dog coronary artery rings were prepared and fixed in a thermostatic muscle tank containing K-H solution. The changes of vascular tension during the same period of time were observed. Results The dose-response curve of CaCl2 in KCl and calcium-free K-H solution was significantly shifted to the right by 10μmol·L-1 or 30μmol·L-1L phorbolil, which markedly decreased the sensitivity of vascular ring and the maximal contractile response. 30μmol·L-1 phlebitin produced a significant acute relaxation in isolated coronary artery rings preconstricted with 50 mmol·L-1 KCl. Nω-L-nitroarginine was added to 1 × 10-4mol·L-1 , 1 × 10-5mol·L-1 of propranolol, 1 × 10-5mol·L-1 of methylene blue, 1 × 10-5mol·L-1 of isosorbide dinitrate (indomethacin) and After the endothelial cells, phlebitin’s acute vasodilatation is not affected. Conclusions The dilation effect of phloretin in isolated coronary rings is mainly through the inhibition of voltage-dependent calcium channels. This dilation effect of phloretin has nothing to do with NO, endothelium, β-adrenoceptors and prostaglandins.