{"title":"The role of cyclic AMP in the regulation of exocytosis in the rat parotid gland: evidence obtained with the isoproterenol analog PI-39.","authors":"T N Spearman, J P Durham, F R Butcher","doi":"","DOIUrl":null,"url":null,"abstract":"<p><p>The isoproterenol analog, PI-39, induced a dose-dependent release of alpha-amylase from rat parotid minces in vitro. This effect was blocked by propranolol, a beta-adrenergic antagonist. PI-39 alone had no effect on parotid cyclic AMP levels or on protein kinase activation as assessed by the activity ratios method. However, PI-39 produced a dose-dependent increase in these parameters when a phosphodiesterase inhibitor was added to tissue minces simultaneously with the isoproterenol analog. Both isoproterenol and PI-39 altered the phosphorylation state of at least three specific endogenous phosphoproteins in (32P)-Pi prelabelled minces. The presence of a phosphodiesterase inhibitor was not required to demonstrate the effects of PI-39 on protein phosphorylation. Studies of endogenous protein phosphorylation in parotid broken cell preparations demonstrated that the phosphorylation of at least two of the PI-39 and isoproterenol-affected phosphoproteins are influenced by cyclic AMP. This study demonstrates that, under certain conditions, it is possible to activate a cyclic AMP-regulated biological process without elevating the total cellular cyclic AMP concentration or the protein kinase activity ratio.</p>","PeriodicalId":15497,"journal":{"name":"Journal of cyclic nucleotide research","volume":"8 4","pages":"225-34"},"PeriodicalIF":0.0000,"publicationDate":"1982-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of cyclic nucleotide research","FirstCategoryId":"1085","ListUrlMain":"","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The isoproterenol analog, PI-39, induced a dose-dependent release of alpha-amylase from rat parotid minces in vitro. This effect was blocked by propranolol, a beta-adrenergic antagonist. PI-39 alone had no effect on parotid cyclic AMP levels or on protein kinase activation as assessed by the activity ratios method. However, PI-39 produced a dose-dependent increase in these parameters when a phosphodiesterase inhibitor was added to tissue minces simultaneously with the isoproterenol analog. Both isoproterenol and PI-39 altered the phosphorylation state of at least three specific endogenous phosphoproteins in (32P)-Pi prelabelled minces. The presence of a phosphodiesterase inhibitor was not required to demonstrate the effects of PI-39 on protein phosphorylation. Studies of endogenous protein phosphorylation in parotid broken cell preparations demonstrated that the phosphorylation of at least two of the PI-39 and isoproterenol-affected phosphoproteins are influenced by cyclic AMP. This study demonstrates that, under certain conditions, it is possible to activate a cyclic AMP-regulated biological process without elevating the total cellular cyclic AMP concentration or the protein kinase activity ratio.