title: Hormonal regulation of calcium current in freshly isolated airway smooth muscle cells.
abstract: Single freshly isolated smooth muscle cells of adult bovine trachea were voltage clamped, and the calcium inward current was separated from K+ currents by blocking the large outward currents with intra- and extracellular Cs+ and extracellular tetraethylammonium chloride. Isoproterenol stimulated peak calcium current (ICa) in a dose-dependent manner through the beta-adrenergic receptor. The isoproterenol effect was not mediated or caused by the stimulation of a K+ or Na+ current, a decrease in the intracellular concentrations of Ca2+ or H+, the stimulation of the Na(+)-H+ or the Na(+)-Ca2+ exchanger. Neither basal nor isoproterenol-stimulated ICa was affected by internal dialysis of the cell with adenosine 3',5'-cyclic monophosphate (cAMP), cAMP analogues, or the catalytic subunit of cAMP-kinase. Internal dialysis of the cells with guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) blocked the stimulation of isoproterenol whereas dialysis with guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) induced an isoproterenol-like maximal increase of ICa. These results show that the beta-adrenergic receptor stimulates the L-type calcium current of isolated tracheal smooth muscle cells independent of cAMP and cAMP-kinase through a GTP/GDP regulated protein.
authors.affiliation: Physiologisches Institut, Medizinische Fakultät, Universität des Saarlandes, Homburg/Saar, Federal Republic of Germany.
authors.forename: A
authors.initials: A
authors.lastname: Welling
authors.forename: J
authors.initials: J
authors.lastname: Felbel
authors.forename: K
authors.initials: K
authors.lastname: Peper
authors.forename: F
authors.initials: F
authors.lastname: Hofmann
mesh_terms: D000420:Albuterol / Q000494:pharmacology; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004594:Electrophysiology / Q000379:methods; D019204:GTP-Binding Proteins / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006728:Hormones / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009568:Nitrendipine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D002712:Chlorides; D006728:Hormones; D013757:Tetraethylammonium Compounds; D013873:Thionucleotides; D006153:Guanosine Diphosphate; D002586:Cesium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D019789:Tetraethylammonium; D011189:Potassium Chloride; C023427:guanosine 5'-O-(2-thiodiphosphate); D009568:Nitrendipine; D011433:Propranolol; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; C028019:cesium chloride; D007545:Isoproterenol; D000420:Albuterol; D011224:Prazosin; D010646:Phentolamine