The nature of the ototoxic actions of ethacrynic acid upon the mammalian endolymph system. II. Structural-functional correlates in the stria vascularis.

The relationship of the ultrastructural changes in the stria vascularis to the functional alterations in the endolymph system was investigated in 23 rats at various times up to 120 min after a single intravenous injection of ethacrynic acid (60 mg kg-1). The overall effect upon the marginal cells, revealed by the development and regression of marked cytoplasmic swelling, was reasonably well correlated with the derangements produced in the strial ion-transporting mechanisms. The pathophysiological relationships of the action upon the intermediate cells was less exact and no unequivocal structural correlates were found for the diminution in membrane permeability and the probable late decrease in energy production. The size of the interstitial spaces was determined mainly by the variations in volume of the marginal and intermediate cells.