EFFECT OF EXTRACELLULAR CALCIUM ON THE INTRACELLULAR CALCIUM LEVEL OFNEWBORN RAT SKIN BASAL CELLS

The effect of extracellular calcium on the intracellular calcium level of newborn rat skin basal cells was examined. The intracellular calci um level of basal cells was affected by the extracellular calcium conc entration on culture of the cells on a collagen-coated filter, but not on a plate. The intracellular calcium ion concentration ([Ca2+](i)) o f cells on a collagen-coated filter with 0.05 mM external CaCl2 was 15 nM and increased to 20-22 nM on culture with 2.0 mM extracellular CaC l2. From these results we concluded that the culture matrix (e.g. cult ure plates, or collagen-coated filters) affects the response of the ba sal cells to changes in the extracellular calcium content. The intrace llular calcium level of Swiss 3T3 cells cultured both on plates and co llagen-coated filters were affected by the extracellular calcium conce ntration. Their [Ca2+](i) was determined as 49-50 nM in the presence o f 0.05 mM external CaCl2, and 54-56 nM in the presence of 2.0 mM CaCl2 . These different responses to extracellular Ca2+ may be due to differ ences in the proliferative profiles of basal cells and fibroblasts.