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 effect on [pH]i. The decrease in [pH]i induced by the Ca(2+)-mobilizing agonists was also observed in Ca(2+)-free medium, but not when the intracellular Ca2+ stores were previously depleted. Ionomycin and thapsigargin elicited a decrease in [pH]i with an increase in cytosolic Ca2+ concentration ([Ca2+]i). The protein kinase C activator and inhibitor had no effect on the agonist-induced decrease in [pH]i. These results suggest that the cytosolic acidification is associated with an increase in [Ca2+]i.