ATP-INDUCED INCREASE IN INTRACELLULAR CA2-PIGS( CONCENTRATION IN THE CULTURED MARGINAL CELL OF THE STRIA VASCULARIS OF GUINEA)

The primary culture of marginal cells from the explant of the stria va scularis of guinea-pigs was established and confirmed by morphological , immunohistochemical and physiological characters of the cultivated c ells. The positive stain of cytokeratin 18 without vimentin and desmin expressions indicated the epithelial origin of the cultured polygonal cells. Electron microscopical findings of cultured cells resembled th e morphological characteristics of marginal cells. The addition of 100 mu M ouabain to the cultured cells significantly increased the intrac ellular Na+ concentration, providing the evidence for the presence of Na+ pump. Using the cultured marginal cells identified by the above-me ntioned findings, the effects of neurotransmitters and hormones in reg ulating intracellular Ca2+ concentration ([Ca2+](i)) were investigated . The addition of 10(-4) M ATP caused an increase in [Ca2+](i), which was independent of the presence of extracellular Ca2+. The rank order of agonist potency was ATP > alpha,beta-methylene ATP > ADP. Adenosine , however, evoked no response. Cultured marginal cells may possess P-2 -purinergic receptors which mobilize Ca2+ from the intracellular Ca2pool. [Marginal cell, Cell culture, Na+/K(+)ATPase, Intracellular Ca2 concentration, ATP].