Yamada H, Seki G, Taniguchi S, Uwatoko S, Suzuki K, Kurokawa K
First Department of Internal Medicine, Tokyo University School of Medicine, Japan.
Biochem Biophys Res Commun. 1996 Aug 5;225(1):215-8. doi: 10.1006/bbrc.1996.1156.
In isolated rabbit proximal tubules the addition of 2.0 microM but not 0.2 microM ionomycin induced a sustained increase in cell pH ([pH]i). This [pH]i response to 2.0 microM ionomycin was shown to be independent of several transporters such as Na+/H+ exchanger, Na(+)-HCO3- cotransporter, Cl-/HCO3- exchanger, or H(+)-ATPase. On the other hand, the removal of extracellular Ca2+ abolished the [pH]i increase or even induced a transient [pH]i decrease in the presence of ionomycin. These results are consistent with the induction of Ca2+/H+ exchange by ionomycin. Therefore Ca2+ ionophores should be used with caution as probes to estimate renal tubule functions.
在离体兔近端小管中，加入2.0微摩尔而非0.2微摩尔的离子霉素可引起细胞内pH值（[pH]i）持续升高。已证明这种对2.0微摩尔离子霉素的[pH]i反应独立于几种转运体，如钠/氢交换体、钠-碳酸氢根共转运体、氯/碳酸氢根交换体或氢-ATP酶。另一方面，去除细胞外钙离子可消除离子霉素存在时的[pH]i升高，甚至引起[pH]i短暂下降。这些结果与离子霉素诱导钙/氢交换一致。因此，作为评估肾小管功能的探针，应谨慎使用钙离子载体。
