DYNAMICS OF NA,K-ATPASE SITES IN LATERAL COCHLEAR WALL TISSUES OF THERAT

The objective of this study was to determine whether varying levels of either the synthetic glucocorticoid, dexamethasone, or the mineraloco rticoid, aldosterone, modulate the quantity of Na,K-ATPase sites in st ria vascularis and spiral ligament tissues. Surgically adrenalectomize d male rats were administered different dosages of dexamethasone or al dosterone for 7 days and subsequently were sacrificed. Na,K-ATPase alp ha-subunits of stria vascularis and spiral ligament homogenates were d etermined quantitatively by enzyme-linked immunosorbent assay, using a monoclonal antibody shown to react with lateral wall Na,K-ATPase alph a-subunit. Elevated serum levels of dexamethasone were correlated with significantly increased Na,K-ATPase alpha-subunit levels in both the stria vascularis and spiral ligament (P<0.05). Elevated serum levels o f aldosterone were correlated with increased Na,K-ATPase alpha-subunit s in the stria vascularis, but not in the spiral ligament (P<0.1). The se data further indicate a positive correlation between increased seru m levels of adrenal steroids and induction of Na,K-ATPase synthesis by such steroids, particularly by dexamethasone.