title: Regulation of adenylate cyclase and cyclic AMP phosphodiesterase by 5-hydroxytryptamine and calcium ions in blowfly salivary-gland homogenates.
abstract: Salivary-gland homogenates contain 5-hydroxytryptamine-stimulated adenylate cyclase. Half-maximal stimulation was obtained with 0.1 microM-5-hydroxytryptamine in the presence of added guanine nucleotides. Gramine antagonized the stimulation of cyclase caused by 5-hydroxytryptamine. In the presence of hormone, guanosine 5'-[gamma-thio]triphosphate produced a marked activation of adenylate cyclase activity. Stimulation of adenylate cyclase by forskolin or fluoride did not require the addition of guanine nucleotides or hormone. In the presence of EGTA, Ca2+ produced a biphasic activation of cyclase activity. Ca2+ at 1-100 microM increased activity, whereas 2000 microM-Ca2+ inhibited cyclase activity. The neuroleptic drugs trifluoperazine and chlorpromazine non-specifically inhibited adenylate cyclase activity even in the absence of Ca2+. The cyclic AMP phosphodiesterase activity in homogenates was not affected by Ca2+ or exogenous calmodulin. This enzyme was also inhibited by trifluoperazine in the absence of Ca2+. These results indicate that Ca2+ elevates adenylate cyclase activity, but had no effect on cyclic AMP phosphodiesterase of salivary-gland homogenates.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D005576:Colforsin; D004175:Diptera / Q000201:enzymology*; D004224:Diterpenes / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006160:Guanosine Triphosphate / Q000378:metabolism; D066298:In Vitro Techniques; D012469:Salivary Glands / Q000187:drug effects / Q000201:enzymology; D012701:Serotonin / Q000494:pharmacology*
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D004224:Diterpenes; D005576:Colforsin; D012701:Serotonin; D006160:Guanosine Triphosphate; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D002118:Calcium