Mechanisms of beta-adrenoceptor mediated increase in delayed rectifier potassium current.
Experiments were carried out in single ventricular cells of the guinea-pig heart. Isoproterenol, forskolin, intracellularly applied cyclic AMP and 3-isobutyl-1-methylxanthine increased the delayed rectifier potassium current (IK). The effect of isoproterenol was abolished by intracellularly applied guanosine 5'-O-(3-thio-triphosphate). These results indicate that isoproterenol stimulates beta-adrenoceptors to activate adenylate cyclase by mediation through the stimulatory GTP-binding protein, and causes an increase in intracellular cyclic AMP levels. Then IK is probably increased by phosphorylation of the IK-channel protein by cyclic AMP-dependent protein kinase.
Iijima
T
T
Department of Pharmacology, Tohoku University School of Medicine, Sendai, Japan.
Taira
N
N
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015290:Second Messenger Systems; D013873:Thionucleotides / Q000494:pharmacology; D016276:Ventricular Function
D011943:Receptors, Adrenergic, beta; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D007545:Isoproterenol; D011188:Potassium