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采用血管环实验和膜片钳细胞贴附式技术分别在器官和细胞分子水平观察多巴胺舒张猪冠状动脉作用及对平滑肌细胞大电导型钙激活钾通道(BKCa)的影响 .结果表明多巴胺引起前列腺素 F2α(PGF2α)预收缩动脉环浓度依赖性舒张反应 ,而不引起高 K+预收缩动脉环舒张反应 .表明多巴胺引起的冠状动脉血管舒张反应依赖于 K+生理浓度梯度的存在 ,结果提示钾通道参与了多巴胺的血管舒张反应 .向细胞浴液内灌流多巴胺增强冠状动脉血管平滑肌细胞膜 BKCa通道活性 .用 DA1受体阻断剂 SCH2 3390预处理细胞 ,完全阻断多巴胺的这一作用 ,而用 β受体阻断剂普萘洛尔无影响 .提示多巴胺通过 DA1受体激活 BKCa通道引起 PGF2α预收缩动脉环舒张反应
The effects of dopamine on diastolic porcine coronary artery and on the large-conductance calcium-activated potassium channel (BKCa) of smooth muscle cells were observed at the level of organs and cells using vascular ring test and patch-clamp cell attachment technique respectively.The results showed that dopamine induced prostaglandin F2α (PGF2α) precontracted arterial ring concentration-dependent vasorelaxation without causing high K + pre-systolic arterial ring diastolic response, suggesting that dopamine-induced coronary vasodilation depends on the presence of K + physiological concentration gradients, suggesting that potassium channels are involved Dopaminergic vasodilatory response.Purification of dopamine into the cell bath enhances the activity of BKCa channels in the coronary artery smooth muscle cells.The pretreatment of cells with the DA1 receptor blocker SCH2 3390 completely blocks this effect of dopamine, Blockade propranolol no effect.It is suggested that dopamine activates BKCa channel through DA1 receptor to cause PGF2α pre-contraction arterial ring relaxation reaction