Carrasquer G, Zhang J Y, Geng Z, Rehm W S, Schwartz M
Department of Medicine, University of Louisville, KY 40292.
Biochim Biophys Acta. 1993 Jul 4;1149(2):195-201. doi: 10.1016/0005-2736(93)90201-a.
Recently, we have shown that polarization of an electrogenic H+/K(+)-ATPase pump located in the secretory (luminal) membrane of the frog gastric mucosa is the major factor contributing to the increase in open circuit potential difference (OCPD) induced by voltage clamping. While this transmucosal polarization was not affected by removal of Cl- and Na+ and minimally affected by increasing the K+ concentration to 79 mM in both nutrient and secretory solutions, it was markedly reduced by 10(-3) M famotidine (beta blocker) or 10(-4) M omeprazole (H+/K(+)-ATPase inhibitor) in the nutrient solution. In present experiments, the effects of three other inhibitors of H+ secretion were examined, namely, cimetidine (beta blocker), SCH 28,080 (H+/K(+)-ATPase inhibitor) and SCN- (non-specific inhibitor). While cimetidine and SCH 28,080 markedly reduced the polarization induced by voltage clamp, SCN- affected the polarization to a lesser extent. These data further support the electrogenicity of the frog gastric mucosa proton pump and the lack of a direct effect of SCN- on the pump.
最近，我们已经表明，位于青蛙胃黏膜分泌（腔）膜中的生电H⁺/K⁺-ATP酶泵的极化是导致电压钳制引起的开路电位差（OCPD）增加的主要因素。虽然这种跨黏膜极化不受去除Cl⁻和Na⁺的影响，并且在营养溶液和分泌溶液中将K⁺浓度增加到79 mM时受到的影响最小，但在营养溶液中加入10⁻³ M法莫替丁（β阻滞剂）或10⁻⁴ M奥美拉唑（H⁺/K⁺-ATP酶抑制剂）会使其明显降低。在目前的实验中，研究了其他三种H⁺分泌抑制剂的作用，即西咪替丁（β阻滞剂）、SCH 28,080（H⁺/K⁺-ATP酶抑制剂）和SCN⁻（非特异性抑制剂）。虽然西咪替丁和SCH 28,080显著降低了电压钳制引起的极化，但SCN⁻对极化的影响较小。这些数据进一步支持了青蛙胃黏膜质子泵的生电性以及SCN⁻对该泵缺乏直接作用。
