title: Low-threshold current is major calcium current in chick ventricle cells.
abstract: Single myocytes were dissociated from the apical ventricles of 14-day-old chick embryos and were maintained in culture for 24 h. Isolated rounded cells, 13-18 microns in diameter with input capacitance averaging 5.2 pF, were selected for whole cell patch-clamp analysis of calcium current (ICa). Two current components, T-type (IT) and L-type (IL), were identified by differences in their voltage thresholds and pharmacological sensitivity, IL was activated by depolarizing steps from -40 mV and was selectively blocked by 1 microM D 600 (methoxyverapamil). IT was obtained by subtracting IL from total ICa and was blocked by 120 microM Ni2+. Identified by threshold potential, sensitivity to Ni2+, or resistance to D 600, IT had a greater current density than has been reported in any adult cardiac tissue. It was also larger than IL and was therefore the major contributor to ICa in this preparation.
authors.affiliation: Department of Anatomy and Cell Biology, Emory University Health Sciences Center, Atlanta, Georgia 30322.
authors.forename: S
authors.initials: S
authors.lastname: Kawano
authors.forename: R L
authors.initials: RL
authors.lastname: DeHaan
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D002642:Chick Embryo; D004553:Electric Conductivity; D005711:Gallopamil / Q000494:pharmacology; D006321:Heart / Q000187:drug effects / Q000196:embryology / Q000502:physiology*; D006352:Heart Ventricles; D009206:Myocardium / Q000166:cytology*; D009532:Nickel / Q000494:pharmacology
chemical_list: D005711:Gallopamil; D009532:Nickel; D002118:Calcium