title: The insensitivity to uncouplers of testis mitochondrial ATPase.
abstract: Albumin-free testis mitochondrial ATPase activity failed to be stimulated by either 2,4-dinitrophenol (DNP) or carbonyl cyanide rho-trifluoromethoxyphenylhydrazone (FCCP). DNP scarcely enhanced the state 4 respiration and mitochondria proved to be poorly coupled. When 1% bovine serum albumin was added to the isolation medium, DNP or FCCP stimulated ATPase nearly twofold and the dose-response curves for the uncouplers on the QO2 reached a plateau at five- to sixfold. The DNP coupling index (q) also showed a 30-40% improvement. A dose-response curve for oligomycin on the rate of [gamma-32P]ATP synthesis showed a stimulation of ATP synthase activity by 10-100 ng inhibitor/mg protein, suggesting a possible blockade of "open" F0 channels. In the albumin preparation oligomycin inhibited ATP synthesis in the range 10-100 ng/mg protein. Since testis ATPase is known to be loosely bound to the membrane, an effect of albumin, improving tightness in the interaction of the F1 and the F0 sectors of the ATPase, is suggested.
mesh_terms: D019297:2,4-Dinitrophenol; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects; D008297:Male; D008560:Membrane Fluidity / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D009840:Oligomycins / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013737:Testis / Q000187:drug effects / Q000201:enzymology*; D014475:Uncoupling Agents / Q000494:pharmacology*
chemical_list: D004140:Dinitrophenols; D007473:Ion Channels; D009840:Oligomycins; D014475:Uncoupling Agents; D012710:Serum Albumin, Bovine; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000251:Adenosine Triphosphatases; D019297:2,4-Dinitrophenol