电流方向和钾离子对青蛙胃黏膜质子泵极化的影响。
Effect of current direction and K+ on polarization of the frog gastric mucosa proton pump.
作者信息
Carrasquer G, Schilb T P, Geng Z, Rehm W S, Schwartz M
机构信息
Department of Medicine (Nephrology), University of Louisville, KY 40292, USA.
出版信息
Biochim Biophys Acta. 1995 Nov 22;1240(1):41-7. doi: 10.1016/0005-2736(95)00173-8.
When current was sent from serosa (S) to mucosa (M) across the frog stomach, there was a polarization (POL) of the open circuit potential (OCPD). POL was not affected by NaCl-free solutions, but was decreased by inhibitors of the H+ pump. In present experiments, current was sent to clamp the PD (VC) across the mucosa in steps of 20 mV up to 100 mV below the control OCPD, that is, current was sent from M to S. All experiments were performed in NaCl-free solutions. The POL was expressed as a % of the difference between the VC PD and the control OCPD. In 4 mM K+ control solutions, the POL was 11.8%; with 10(-3) M omeprazole (H+/K+ pump inhibitor), 1.1; with 10(-5) M SCH 28080 (H+/K+ pump inhibitor), 3.6; with 10(-3) M famotidine (H2 blocker), 1.6; and with 10(-2) M SCN-, 25.4 (inhibition of H+ sec, but not of the pump); in 79 mM K+ control solutions, 26.2; with 10(-3) M omeprazole, 4.2; with 10(-5) M SCH 28080, 15.9; with 10(-3) M famotidine, 5.6; and with 10(-2) M SCN-, 29.9. POL was higher in high K+ than in low K+ solutions contrary to what was observed in previous experiments with current sent from S to M. Results are explained on the basis of an electrogenic H+/K(+)-ATPase pump which includes a H+ channel, permeable to K+. With high K+ solutions, K+ is driven through the H+ channel onto the antiporter (ATPase) when current is sent from M to S, resulting in a greater POL of the pump.
当电流从蛙胃的浆膜（S）流向黏膜（M）时，开路电位（OCPD）会出现极化（POL）现象。POL不受无氯化钠溶液的影响，但会被H⁺泵抑制剂降低。在当前实验中，电流以20 mV的步长发送，以钳制跨黏膜的电位差（VC），直至比对照OCPD低100 mV，即电流从M流向S。所有实验均在无氯化钠溶液中进行。POL表示为VC电位差与对照OCPD差值的百分比。在4 mM K⁺对照溶液中，POL为11.8%；使用10⁻³ M奥美拉唑（H⁺/K⁺泵抑制剂）时，为1.1%；使用10⁻⁵ M SCH 28080（H⁺/K⁺泵抑制剂）时，为3.6%；使用10⁻³ M法莫替丁（H₂受体阻滞剂）时，为1.6%；使用10⁻² M SCN⁻时，为25.4%（抑制H⁺分泌，但不抑制泵）；在79 mM K⁺对照溶液中，为26.2%；使用10⁻³ M奥美拉唑时，为4.2%；使用10⁻⁵ M SCH 28080时，为15.9%；使用10⁻³ M法莫替丁时，为5.6%；使用10⁻² M SCN⁻时，为29.9%。与之前从S流向M发送电流的实验结果相反，高钾溶液中的POL高于低钾溶液。实验结果是基于一种包括对K⁺通透的H⁺通道的电生性H⁺/K⁺-ATP酶泵来解释的。在高钾溶液中，当电流从M流向S时，K⁺通过H⁺通道驱动到反向转运体（ATP酶）上，导致泵的POL更大。
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