Characterization of an electrogenic ATP and chloride-dependent proton translocating pump from rat renal medulla.

摘要: To study acidification mechanisms in the distal nephron, microsomes were prepared from rat renal medulla by differential centrifugation. Microsomes enriched enzyme marker gamma-glutamyl transferase and contained an ATP-dependent proton pump, as evidenced ATP-dependent, 3,3',4',5-tetrachlorosalicylanilide-reversible quenching of acridine orange fluorescence. Acidification was vanadate-insensitive, but completely inhibited micromolar N-ethylmaleimide. Maximal achieved presence halide (Cl-, Br-) only not attainable with potassium-valinomycin diffusion potentials without ion. Microsomal ATPase activity neither chloride- nor N-ethylmaleimide-sensitive. A chloride conductance observed vesicles which had undergone acidification. An N-ethylmaleimide-inhibitable, 3,3',4',5-tetrachlorosalicylanilide-reversible, chloride-attenuated quench bis(1,3-dibutylbarbituric acid-(5] pentamethinoxonol fluorescence seen, consistent net transfer positive charge into vesicles. Nonetheless, intravesicular increased initial rate, perhaps increasing availability ion to transport site. Our results are electrogenic, pump regulated a voltage-sensitive