title: Characterization of gap junctions between pairs of Leydig cells from mouse testis.
abstract: Leydig cells are coupled in vivo by numerous gap junctions. In vivo and in vitro cells were immunolabeled by connexin 43 (Cx43) but not by Cx26 or Cx32 antibodies; immunoblotting confirmed specificity of Cx43 labeling. Pairs of Leydig cells dissociated from mouse testis were studied by dual whole cell voltage clamp, and a high incidence of dye (n = 20) and electrical coupling (n = 60; > 90%) was found. Coupling coefficients were near 1 and junctional conductance (gj) averaged 7.2 +/- 1.2 nS (SE, n = 40). Large transjunctional voltage (Vj) decreased gj; currents decayed exponentially with time constants of seconds that decreased at greater Vj. The residual conductance at large Vj was at least approximately 40% of the initial conductance. Exposure of cell pairs to saline solutions saturated with CO2 (n = 15) or containing 2 mM halothane (n = 15) or 3.5 mM heptanol (n = 15) rapidly and reversibly reduced gj. In eight cell pairs, gating of single junctional channels was observed during halothane-induced reduction in gj. Most gating events at Vj < 40 mV were fit by a Gaussian distribution with a mean of approximately 100 pS. With Vj > 40 mV, smaller transitions of approximately 30 pS were also recorded, and the frequency and duration of the approximately 100-pS transitions decreased. Also, approximately 70-pS transitions between 30- and 100-pS conductances were observed in the absence of 70-pS transitions to or from the baseline, indicating that the 30-pS conductance was a substate induced by large Vj.
authors.affiliation: Department of Neuroscience, Albert Einstein College of Medicine, Bronx 10461.
authors.forename: E M
authors.initials: EM
authors.lastname: Pérez-Armendariz
authors.forename: M C
authors.initials: MC
authors.lastname: Romano
authors.forename: J
authors.initials: J
authors.lastname: Luna
authors.forename: C
authors.initials: C
authors.lastname: Miranda
authors.forename: M V
authors.initials: MV
authors.lastname: Bennett
authors.forename: A P
authors.initials: AP
authors.lastname: Moreno
mesh_terms: D000438:Alcohols / Q000494:pharmacology; D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D017629:Gap Junctions / Q000502:physiology*; D006221:Halothane / Q000494:pharmacology; D019850:Heptanol; D007473:Ion Channels / Q000502:physiology; D007985:Leydig Cells / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains
chemical_list: D000438:Alcohols; D007473:Ion Channels; D002245:Carbon Dioxide; D019850:Heptanol; D006221:Halothane