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TIME DEPENDENT CONVERSION FROM α 1 ‐ to β‐ADRENOCEPTOR‐ MEDIATED GLYCOGENOLYSIS IN ISOLATED RAT HEPATOCYTES: ROLE OF MEMBRANE PHOSPHOLIPASE A 2 AND PROTEIN KINASE C
Author(s) -
Ishac E. J. N.,
Kunos G.
Publication year - 1987
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1987.tb00994.x
Subject(s) - glycogenolysis , protein kinase c , activator (genetics) , protein kinase a , phospholipase c , cytosol , isoprenaline , chemistry , biology , endocrinology , medicine , biochemistry , receptor , signal transduction , kinase , enzyme , stimulation , metabolism
SUMMARY 1. Incubation of isolated rat liver cells in a serum‐free buffer leads to the reduction of the glycogenolytic effect of phenylephrine and the simultaneous emergence of the response to isoprenaline within 4 h. 2. Inhibitors of phospholipase A 2 reverse the adrenergic activation of phosphorylase a from a β‐ to an α 1 ‐receptor‐mediated event. Conversely activators of phospholipase A 2 enhance the conversion. 3. In vitro incubation of hepatocytes leads to a translocation of protein kinase C from the cytosol to the membrane which can be mimicked by phorbol 12‐myristate 13‐acetate (PMA), an activator of protein kinase C. PMA is also associated with transformation from α 1 to β‐adrenoceptor‐mediated glycogenolysis. 4. It is proposed that coupling of hepatic α 1 and β‐adrenoceptors to postreceptor pathways are regulated by changes in membrane phospholipase A 2 and protein kinase C activity.