Extracellular ATP and benzoyl-ATP (Bz-ATP) increased the release of [3H] arachidonic acid ([3H] AA) from prelabeled rat submandibular gland (RSMG) ductal cells respectively two-and threefold. Both agonists also increased the release of [3H] AA from acini but at a lower level (+ 50% and+ 100% respectively). Carbachol had no significant effect on either cellular population. In ductal cells phorbol myristate acetate, an activator of protein kinase C, slightly increased the basal release of [3H] AA but did not affect the release of [3H] AA in response to ATP. Staurosporine, an inhibitor of protein kinases, inhibited the response to the purines. The removal of calcium from the extracellular medium decreased the response to ATP and Bz-ATP. Only barium could partly substitute for calcium to restore the purinergic response. Zinc inhibited the release of [3H] AA. Permeabilization of the cells with streptolysin O …