title: Beta-adrenergic modulation in the heart. Independent regulation of K and Ca channels.
abstract: The temperature-dependence of the actions of beta-receptor agonists and adenylate cyclase stimulation on both calcium and delayed rectifier potassium channel ionic currents were examined in patch-clamped guinea pig ventricular myocytes. We report that temperature can separate the beta-receptor mediated modulation of potassium and calcium channels. Receptor-mediated increases in the delayed rectifier potassium current, but not the calcium current were very temperature-dependent over the range of 19 to 32 degrees C. At room temperature (19-22 degrees C) the beta-agonist isoproterenol produced a large enhancement of the calcium current but had no effect on the delayed rectifier current. In contrast, at warmer temperatures (28-32 degrees C) both currents increased in the presence of the agonist. This temperature-sensitivity also existed for direct stimulation of adenylate cyclase by forskolin. Thus, cardiac calcium and potassium channels appear to be independently regulated during adrenergic stimulation.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D011188:Potassium / Q000378:metabolism*; D013816:Thermodynamics; D016276:Ventricular Function
chemical_list: D007473:Ion Channels; D007545:Isoproterenol; D011188:Potassium; D002118:Calcium