title: Effects of thiopental on contractile and electrophysiological properties of single canine left ventricular cells.
abstract: The effects of thiopental on contraction, membrane potential and membrane ionic currents were studied in single canine left ventricular cells. Thiopental 10(-5) and 10(-4) mol/l reduced the cell-shortening from 7.02 +/- 0.64 microns to 5.66 +/- 1.39 and 3.48 +/- 0.64 microns respectively (mean +/- S.D., N = 10, 0.5 Hz). This effect was enhanced in higher (> 1.0 Hz) electrical stimulation frequencies. Also, thiopental decreased the plateau phase and shortened the duration of action potential. On the other hand, voltage clamp experiment revealed that thiopental 10(-6), 10(-5), and 10(-4) mol/l reduced peak Ca2+ current from 520 +/- 48 pA to 387 +/- 60 pA, 261 +/- 84 pA, and 84 +/- 36 pA respectively (mean +/- S.D., N = 8), and showed a use-dependent block of Ca2+ current. However, only a high dose of thiopental (10(-4) mol/l) inhibited the Na+ current. We conclude that the negative inotropic effect of thiopental on the heart is mediated mainly via inhibition of the Ca2+ current.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kubo
authors.forename: N
authors.initials: N
authors.lastname: Hatakeyama
authors.forename: T
authors.initials: T
authors.lastname: Satone
authors.forename: N
authors.initials: N
authors.lastname: Shibuya
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: S
authors.initials: S
authors.lastname: Yamamura
authors.forename: Y
authors.initials: Y
authors.lastname: Momose
mesh_terms: D000818:Animals; D004285:Dogs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D013874:Thiopental / Q000494:pharmacology*
chemical_list: D006993:Hypnotics and Sedatives; D013874:Thiopental