title: Phorbol ester effect on the hydrosmotic response to vasopressin in frog skin.
abstract: Serosal preincubation of frog skin with tetradecanoyl phorbol acetate, TPA, an activator of protein kinase C, inhibits the hydrosmotic response elicited by vasopressin (AVP) but not that induced by 8br-cAMP. This proves that serosal TPA primarily influences a pre-cAMP step. The TPA-induced inhibition of AVP response appears to be related to TPA-induced prostaglandin synthesis. The pretreatment with naproxen, in fact, prevents the inhibition induced by serosal TPA on the AVP response. On the contrary, mucosal TPA produces a more marked inhibition of the response to AVP and significantly diminishes the water flow induced by 8br-cAMP; this suggests that mucosal TPA interferes mainly with a post-cAMP step. Furthermore, naproxen is unable to completely prevent the inhibition induced by mucosal TPA on AVP response thus indicating that mucosal TPA may also activate a prostaglandin-independent mechanism able to inhibit one of the last steps of the hydrosmotic response to AVP.
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D066298:In Vitro Techniques; D009288:Naproxen / Q000494:pharmacology; D009994:Osmolar Concentration; D011893:Rana esculenta; D012867:Skin / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D014667:Vasopressins; D001127:Arginine Vasopressin; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D009288:Naproxen; D013755:Tetradecanoylphorbol Acetate