Altered calcium homeostasis in the rat cochlear duct and endogenous corticosteroid insufficiency

Free calcium concentration (\(C_{Ca} ^{2 + } \)) profiles were evaluated in perilymph, endolymph, marginal cells, spiral ligament and blood serum of adrenalectomized (ADX) rats. Free\(C_{Ca} ^{2 + } \) was significantly greater in perilymph and significantly reduced in the serum of the ADX animals as compared to sham-operated animals. In addition, higher levels of free (\(C_{Ca} ^{2 + } \)) were found in the spiral ligament in ADX animals. Free (\(C_{Ca} ^{2 + } \)) did not appear to be affected by ADX in marginal cells and endolymph. These data suggest that marked reductions in endogenous levels of corticosteroids may have a systematic effect on free\(C_{Ca} ^{2 + } \) that is detectable in blood serum as well as cochlear fluids and tissues.