Hilden S A, Johns C A, Madias N E
Department of Medicine, Tufts University School of Medicine, Boston, Massachusetts.
Am J Physiol. 1988 Nov;255(5 Pt 2):F885-97. doi: 10.1152/ajprenal.1988.255.5.F885.
An endosomal fraction isolated from rabbit renal cortex by a novel, fast, and simple procedure was enriched in ATP-dependent H+ pumping that was oligomycin insensitive but was inhibited by dicyclohexylcarbodiimide (DCCD), N-ethylmaleimide (NEM), Zn2+, Hg2+, diethylstilbestrol, mersalyl, and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. No substantial Na+-H+ exchange was detected. Electrogenicity of the pump was demonstrated using [14C]-SCN-. In addition, these membranes featured ATP-dependent Cl- flux. The ATP-driven H+ pumping had an absolute requirement for Cl-: an inside-negative membrane potential was not a substitute for Cl-. The protonophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone inhibited ATP-driven Cl- uptake but no inhibition was observed with nigericin. Finally, both ATP-driven H+ pumping and ATP-dependent Cl- flux were inhibited by Cl(-)-channel inhibitors. Part, or all, of the absolute dependence on Cl- may derive from a Cl- channel, the function of which is intimately related to H+ pumping by the ATPase. Flux through this Cl- channel may be regulated by one or more factors, including ATP, membrane potential, and pH.
