Vanadate-induced intracellular calcium elevation in the stria vascularis of the guinea pig: fluorescence ratio imaging microscopy.

Cytoplasmic free calcium has been observed in fura 2-loaded stria vascularis of the guinea pig. Following the application of vanadate, the cytosolic Ca2+ concentration increased by 45%. Complete substitution of extracellular Na+ with N-methyl D-glucamine did not alter the free calcium concentration. These findings suggest that the Ca2+ transport in the stria vascularis is mediated by a Ca2(+)-ATPase enzyme mechanism rather than Na(+)-Ca2+ exchange.