Dynamics of Na,K-ATPase sites in lateral cochlear wall tissues of the rat

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Abstract
The objective of this study was to determine whether varying levels of either the synthetic glucocorticoid, dexamethasone, or the mineralocorticoid, aldosterone, modulate the quantity of Na,K-ATPase sites in stria vascularis and spiral ligament tissues. Surgically adrenalectomized male rats were administered different dosages of dexamethasone or aldosterone for 7 days and subsequently were sacrificed. Na,K-ATPase α-subunits of stria vascularis and spiral ligament homogenates were determined quantitatively by enzyme-linked immunosorbent assay, using a monoclonal antibody shown to react with lateral wall Na,K-ATPase α-subunit. Elevated serum levels of dexamethasone were correlated with significantly increased Na,K-ATPase α-subunit levels in both the stria vascularis and spiral ligament (P 〈 0.05). Elevated serum levels of aldosterone were correlated with increased Na,K-ATPase α-subunits in the stria vascularis, but not in the spiral ligament (P 〈 0.1). These data further indicate a positive correlation between increased serum levels of adrenal steroids and induction of Na,K-ATPase synthesis by such steroids; particularly by dexamethasone.