INHIBITORY EFFECT OF ERYTHROMYCIN ON ION-TRANSPORT BY STRIA VASCULARIS AND VESTIBULAR DARK CELLS

A previous study showed that systemic administration of erythromycin c aused a reversible decline in the endocochlear and cochlear microphoni c potentials. Those data were thought to suggest that erythromycin cau sed hearing loss by interference with ion transport processes in the s tria vascularis. The present study was undertaken to test this hypothe sis by measuring the effects of erythromycin perfused on either the ap ical or basolateral side on the transepithelial short circuit current (I-sc), a measure of the K+ secretion rate. I-sc was measured from pre parations of strial marginal cells and the homologous vestibular dark cells in vitro with a micro-Ussing chamber. Erythromycin was found to have no effect when perfused on the apical side but to cause a reversi ble decrease in I-sc when perfused on the basolateral side for both ep ithelia. These data are consistent with the notion that at least one o totoxic effect of erythromycin is the inhibition of K+ secretion in th e inner ear.