title: Differential effect of Ca2+ on oxidant-induced lethal cell injury and alterations of membrane functional integrity in renal cortical slices.
abstract: This study was undertaken to examine if modulations of intracellular and extracellular Ca2+ affect the lethal cell injury and impairment of membrane transport function induced by oxidants in rabbit renal cortical slices. The oxidant t-butylhydroperoxide (t-BHP) and H2O2 increased lactate dehydrogenase (LDH) release and inhibited PAH uptake in a dose-dependent manner, but the potency of H2O2 was 100 times lower than that of t-BHP. Catalase prevented the effect of H2O2 but not that of t-BHP, suggesting that lower potency of H2O2 is attributed to the endogenous catalase activity. t-BHP induced lipid peroxidation and inhibited microsomal (Na+)-(K+)-ATPase activity. Omission of Ca2+ from the medium or addition of Ca2+ channel blockers (verapamil, diltiazem, and nifedipine) prevented the oxidant-induced LDH release. Similar effect was observed by addition of La3+. Buffering intracellular Ca2+ with BAPTA/AM decreased the oxidant-induced LDH release. However, the oxidant-induced impairment in PAH uptake was not altered under the same conditions. Also, the inhibition of microsomal (Na+)-(K+)-ATPase activity by t-BHP was not affected by verapamil, La3+, and BAPTA/AM. Dithiothreitol and glutathione prevented the oxidant-induced LDH release and reduction of PAH uptake and impeded the oxidant-induced inhibition of (Na+)-(K+)-ATPase activity and lipid peroxidation. Effects of t-BHP on TEA uptake were similar to those on PAH uptake. Modulations of intracellular or extracellular Ca2+ had little effect on the oxidant-induced lipid peroxidation. Glycine did not exert protective effect against the oxidant-induced cell injury. These results suggest strongly that Ca2+ plays an important role in the oxidant-induced LDH release but not in the oxidant-induced alterations of membrane transport function in rabbit renal cortical slices. The role of Ca2+ in oxidant-induced LDH release is not apparently associated with peroxidation of membrane lipid.
authors.affiliation: Department of Physiology, College of Medicine, Pusan National University, Korea.
authors.forename: Y K
authors.initials: YK
authors.lastname: Kim
authors.forename: Y H
authors.initials: YH
authors.lastname: Kim
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005978:Glutathione / Q000502:physiology; D006861:Hydrogen Peroxide / Q000633:toxicity*; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D010545:Peroxides / Q000633:toxicity*; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013757:Tetraethylammonium Compounds / Q000493:pharmacokinetics; D010130:p-Aminohippuric Acid / Q000493:pharmacokinetics; D020122:tert-Butylhydroperoxide
chemical_list: D010545:Peroxides; D013757:Tetraethylammonium Compounds; D004533:Egtazic Acid; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium; D010130:p-Aminohippuric Acid