Effects of prostaglandins on [Ca2+]i and adenylate cyclase activity in isolated porcine gastric mucous cells.
In porcine gastric mucous cells, isolated enzymatically from the fundic mucosa and enriched by counterflow centrifugation, PGE2 (1 microM) increased adenylate cyclase activity to 225% and, distinct from that documented for other species, also [Ca2+]i, measured fluorimetrically with Fura2/AM, in Ca(2+)-containing and Ca(2+)-free incubation medium to 182% and 165% of control values, respectively. PGF2 alpha, PGD2, the stable prostacyclin analogue iloprost and the thromboxane-mimetic U46619 had no significant effects on adenylate cyclase activity and [Ca2+]i. Histamine (10 microM) stimulated adenylate cyclase activity to 236% of control value, an effect which could be blocked by the H2-receptor antagonist ranitidine. However, histamine and the activators of the cAMP system forskolin and dibutyryl cAMP had no significant effect on [Ca2+]i, indicating that an activation of the adenylate cyclase/cAMP system per se does not result in an increase in [Ca2+]i. These data suggest that prostanoids stimulate adenylate cyclase activity and [Ca2+]i in gastric mucous cells via activation of EP-receptors linked to both second messenger systems.