Adenine nucleotides of the organ of Corti under metabolic stress

The purpose of the reported experiments was to measure the concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) in the organ of Corti in order to arrive at estimates of three commonly used adenylate ratios. Under normal conditions the concentrations of ATP, ADP, and AMP amounted to 15.8, 3.9, and 0.53 mmoles/kg dry weight, respectively. Of the three substances, AMP is the most sensitive indicator of metabolic stress, since ischemia of 65 seconds leads to an increase of 155%. Under normal conditions the adenylate energy charge, the energy status, and the phosphorylation state amounted to status by 50%, and the phosphorylation state by 76%. The apparent equilibrium constant of adenylate kinase of the organ of Corti was found to be 0.55. The potential significance of these data and their relationship to the situation in the stria vascularis are discussed.