THE CYTOSOLIC ACIDIFICATION IN RAT PAROTID CELLS IS ASSOCIATED WITH AN INCREASE IN CYTOSOLIC CA2+ CONCENTRATION

A transient decrease in cytosolic pH ([pH]i) in rat parotid cells was evoked by the addition of carbachol (CCh), phenylephrine, or substance P, whereas isoproterenol and dibutyryl cyclic AMP had little or no ef fect on [pH]i. The decrease in [pH]i induced by the Ca2+-mobilizing ag onists was also observed in Ca2+-free medium, but not when the intrace llular Ca2+ stores were previously depleted. Ionomycin and thapsigargi n elicited a decrease in [pH]i with an increase in cytosolic Ca2+ conc entration ([Ca2+]i). The protein kinase C activator and inhibitor had no effect on the agonist-induced decrease in [pH]i. These results sugg est that the cytosolic acidification is associated with an increase in [Ca2+]i.