Verapamil和Mn~（2＋）对缺氧及缺氧复氧心肌细胞内pH的影响

采用荧光探针ＢＣＥＣＦ／ＡＭ结合计算机图像处理技术测定不同时间的缺氧和缺氧复氧单心肌细胞内ｐＨ的变化以及Ｃａ２＋通道阻滞剂Ｖｅｒａｐａｍｉｌ和Ｎａ＋－Ｃａ２＋交换抑制剂Ｍｎ２＋对其的影响。结果显示随着缺氧时间的延长，细胞内ｐＨ也逐渐降低。复氧开始４０ｍｉｎ内，细胞内ｐＨ并未恢复正常。Ｖｅｒａｐａｍｉｌ能减轻缺氧细胞内酸化程度并使其接近正常水平（Ｐ＞０．０５），却未能减轻缺氧复氧细胞内的酸化。无论是缺氧或缺氧复氧心肌细胞，Ｍｎ２＋均未能减轻细胞内的酸化程度。本实验结果提示缺氧和缺氧复氧时细胞内酸化途径并非完全一致。ＶｅｒａＰａｍｉｌ抑制缺氧细胞内ｐＨ下降是其保护缺氧心肌作用的机制之一。

Effects of verapamil and Mn￣(2+) on intracellular pH in isolated myocytes during hypoxia and reoxygenation

Fluorescent probe BCECF/AM combined with computer image processing technique was used to investigate intracellular pH (pHi)variation in various stages of hypoxic and reoxygenated myocytes and the effects of calcium channel blocker, verapamil,and Na -Ca2 exchange inhibitor Mn2 on this variation.Results indicated that intracellular pH decreased gradually along with the prolongation of hypoxia. During 40 min of reoxygenation, the pHi did not return to normal.Verapamil inhibited pHi decrease during hypoxia but had no significant effect on pHi during reoxygenbation.The effect of Mn2 on intracellular pH during both hypoxia and reoxygenation was not significant.Our study suggested that the mechanism of intracellular acidosis induced by hypoxia may not be the same as one induced by reoxygenation and one of the protective effects of verapamil on hypoxic myocytes is its inhibition of decrease in intracellular pH in myocytes.