Adenosine triphosphate and phosphocreatine levels in cochlear structures. Use rate and effect of salicylates.

Guinea pigs were injected with various dosages of salicylate for varying time periods. The temporal bones were removed, frozen quickly, freeze-dried, and the cochlea was dissected into essential auditory component parts and subjected to microchemical analysis for phospho-creatine (P-creatine) and adenosine triphosphate (ATP) levels. It was found that high energy phosphates were not decreased by therapeutic or acutely toxic levels of salicylate. Only when chronic intoxication with salicylate was accomplished was there a reduction in ATP and P-creatine. The data presented do not provide support for the widely held view that uncoupling of oxidative phosphorylation or inhibition of enzymes involved in energy generation in the inner ear structures studied (organ of Corti, stria vascularis, Reissner's membrane, modiolar blood vessels, cochlear nerve and spiral ganglion) are the mechanisms by which salicylates cause reversible hearing loss. The study confirms the existence of a P-creatine gradient opposite to the well known glycogen gradient in the organ of Corti (Krzanowski JJ Jr, Matschinsky M: J Histochem 19:321, 1971) and suggests a relatively uniform energy use rate of this tissue for all four turns (20 mmoles of approximately phosphorus used/kg dry weight/min).