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 (g(j)) averaged 7.2 ± 1.2 nS (SE, n = 40). Large transjunctional voltage (V(j)) decreased g(j); currents decayed exponentially with time constants of seconds that decreased at greater V(j). The residual conductance at large V(j) was at least ~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 g(j). In eight cell pairs, gating of single junctional channels was observed during halothane-induced reduction in g(j). Most gating events at V(j) < 40 mV were fit by a Gaussian distribution with a mean of ~100 pS. With V(j) > 40 mV, smaller transitions of ~30 pS were also recorded, and the frequency and duration of the ~100-pS transitions decreased. Also, ~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 V(j).
|Original language||English (US)|
|Journal||American Journal of Physiology - Cell Physiology|
|Issue number||2 36-2|
|State||Published - Jan 1 1994|
- connexin 43
ASJC Scopus subject areas
- Cell Biology