title: Ionic currents in single smooth muscle cells of the human vas deferens.
abstract: OBJECTIVE
  Smooth muscle cells of the vas deferens have an important role in carrying sperms to the exterior but little is known of their electrophysiological properties. We characterized the voltage-gated ion channel currents in single smooth muscle cells of the human vas deferens (HVSMCs).
  
  
  METHODS
  We observed contractile responses of 8 circular smooth muscle strips of the human vas deferens to a high concentration (10 mM) of tetraethylammonium. HVSMCs were isolated using proteolytic enzymes (collagenase and papain), and were used for an electro-physiological study using whole cell and inside-out patch clamp configurations.
  
  
  RESULTS
  The application of 10 mM tetraethylammonium induced rhythmic contractions of the strips. When HVSMCs were dialyzed with a KCl solution, step depolarizations of membrane potential evoked oscillatory outward K currents that were not inactivated. The large conductance Ca activated K (BKCa) and delayed rectifier components of the outward current were identified. The BKCa channel showed a large single channel conductance (162.7 +/- 13.2 pS with 5 mM K in the patch pipette). Two types of Ca currents were identified in the whole cell configuration. With a cell held at -50 mV an L-type Ca current was present during a depolarizing step pulse. From a holding potential of -90mV L-type and T-type Ca currents were elicited by depolarizing step pulses.
  
  
  CONCLUSIONS
  HVSMCs have 2 (L and T) types of Ca channels and 2 types of K (BKCa and delayed rectifier) channels. Voltage dependent changes of these ion channels and their interactions may be important in regulating vas contractility.
authors.affiliation: Department of Physiology, College of Medicine, Chung-Ang University, Seoul, South Korea.
authors.forename: So Young
authors.initials: SY
authors.lastname: Park
authors.forename: Moo Yeol
authors.initials: MY
authors.lastname: Lee
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Keum
authors.forename: Soon Chul
authors.initials: SC
authors.lastname: Myung
authors.forename: Sae Chul
authors.initials: SC
authors.lastname: Kim
mesh_terms: D000328:Adult; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type / Q000502:physiology; D020747:Calcium Channels, T-Type / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000166:cytology*; D015221:Potassium Channels / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology; D014649:Vas Deferens / Q000166:cytology* / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated