Cl(-)-dependent ATP-driven H+ transport in rabbit renal cortical endosomes.
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.
Hilden
S A
SA
Department of Medicine, Tufts University School of Medicine, Boston, Massachusetts.
Johns
C A
CA
Madias
N E
NE
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology*; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D007473:Ion Channels / Q000378:metabolism; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009550:Nigericin / Q000494:pharmacology; D009840:Oligomycins / Q000494:pharmacology; D015388:Organelles / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D011522:Protons; D011817:Rabbits; D012458:Salicylanilides / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013861:Thiocyanates / Q000378:metabolism
D002712:Chlorides; D004232:Diuretics; D007473:Ion Channels; D009840:Oligomycins; D011522:Protons; D012458:Salicylanilides; D013861:Thiocyanates; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D004024:Dicyclohexylcarbodiimide; D000255:Adenosine Triphosphate; D012964:Sodium; D006180:Proton-Translocating ATPases; C003390:3,3',4',5-tetrachlorosalicylanilide; D005033:Ethylmaleimide; D009550:Nigericin