title: MCI-154 activates the Ca(2+)-activated K+ channel of vascular smooth muscle cells.
abstract: The aim of this study was to examine the effects of MCI-154, a new positive inotropic agent with vasodilating properties, on the Ca2+-activated K+ channel (KCa channel) of vascular smooth muscle cells. Cultured smooth muscle cells from a porcine coronary artery were studied using the patch-clamp technique. Extracellular application of 100 microM MCI-154 activated the KCa channel in intact cell-attached patch configurations. In excised inside-out patch configurations, application of 100 microM MCI-154 to the cytosolic side activated the KCa channel directly, suggesting that the Ca2+ sensitivity of the KCa channel itself is modulated. Though extracellular application of 100 microM amrinone, a phosphodiesterase inhibitor, activated the KCa channel in the cell-attached patch configurations, application of 100 microM amrinone to the cytosolic side could not activate the KCa channel in inside-out patch configurations. These results indicate that different from amrinone, MCI-154 can modulate Ca2+ sensitivity of the KCa channel in vascular smooth muscle cells.
authors.affiliation: Second Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Y
authors.initials: Y
authors.lastname: Nakaya
authors.forename: K
authors.initials: K
authors.lastname: Saito
authors.forename: F
authors.initials: F
authors.lastname: Kishi
authors.forename: M
authors.initials: M
authors.lastname: Takakura
authors.forename: M
authors.initials: M
authors.lastname: Nomura
mesh_terms: D000676:Amrinone / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D015221:Potassium Channels / Q000819:agonists*; D011724:Pyridazines / Q000494:pharmacology*; D013552:Swine; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D010726:Phosphodiesterase Inhibitors; D015221:Potassium Channels; D011724:Pyridazines; D014665:Vasodilator Agents; C052228:MCI 154; D000676:Amrinone; D002118:Calcium