Changes of the stria vascularis induced by ethacrynic acid.

Histological changes in the stria vascularis of guinea pigs after the injection of ethacrynic acid (50 mg/kg) were investigated using a transmission electron microscope and a scanning electron microscope. The changes in permeability in the stria vascularis was also observed using horseradish peroxidase as a tracer. The pathological changes originating in endothelial cells of stria blood vessels and intermediate cells spread into the marginal cells and basal cells. The most remarkable changes were observed one hour after the injection of ethacrynic acid. Subsequently, recovery began in the cells around the blood capillaries and was most complete 3--4 hours after the injection. It is presumed that the strial damages by the ethacrynic acid are caused not only by the direct effect of this drug on the strial cells but also by the disturbances of blood flow and permeability of the capillaries.