Phosphorylation of ryanodine receptors in rat myocytes during beta-adrenergic stimulation.
We studied beta-adrenergic agonist-stimulated phosphorylation of the ryanodine receptor in rat cardiac myocytes. The ryanodine receptor solubilized from myocytes and immunoprecipitated by a monoclonal antibody against canine cardiac ryanodine receptor was phosphorylated by the catalytic subunit of cAMP-dependent protein kinase (PKA). Incubation of saponin-permeabilized myocytes with [gamma-32P]ATP also induced ryanodine receptor phosphorylation, which was enhanced significantly in the presence of isoproterenol. This stimulating action of isoproterenol was suppressed by the beta-adrenergic antagonist, propranolol. On the other hand, exogenously added cAMP caused a much larger stimulation of phosphorylation of the ryanodine receptor in permeabilized myocytes. The beta-agonist-induced phosphorylation of the ryanodine receptor was also observed in intact myocytes from the newborn rat heart. These results suggest that the ryanodine receptor is phosphorylated by PKA during beta-adrenergic stimulation of cardiac myocytes.
Department of Biology, Faculty of Science, Osaka University.
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A
Yoshida
M
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Takahashi
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Imagawa
M
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Shigekawa
H
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Takisawa
T
T
Nakamura
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D002478:Cells, Cultured; D006352:Heart Ventricles / Q000166:cytology; D007545:Isoproterenol / Q000494:pharmacology; D009124:Muscle Proteins / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011950:Receptors, Cholinergic / Q000378:metabolism*; D012433:Ryanodine / Q000032:analysis; D019837:Ryanodine Receptor Calcium Release Channel; D014316:Tritium
D000318:Adrenergic beta-Agonists; D015220:Calcium Channels; D009124:Muscle Proteins; D011950:Receptors, Cholinergic; D019837:Ryanodine Receptor Calcium Release Channel; D014316:Tritium; D012433:Ryanodine; D007545:Isoproterenol