Altered profile of ACh-elicited single-channel
currents in SCG neurons in α3-deficient mice. The SCG neurons from
+/+ mice express five conductance classes of nAChRs. In contrast, the
SCG neurons from −/− mice display many fewer channel openings which
contribute to only two well-defined conductance classes.
(a) Sample traces of ACh-gated single-channel currents
in cell attached patches (membrane holding potential +50 mV)
demonstrated that the +/+ mice expressed both more channel openings
and openings of longer duration than the −/− mice.
(b) Amplitude analysis of +/+ SCG neurons indicated
that there were five amplitude classes (γ1+/+ ≈ 9 pS,
γ2+/+ ≈ 18 pS, γ3+/+ ≈ 25 pS,
γ4+/+ ≈ 35 pS, and γ5+/+ ≈ 41 pS; 3,148
events pooled from four cells). In contrast, amplitude analysis of
−/− SCG neurons revealed only two well defined conductance classes
(γ1−/− ≈ 18 pS and γ2−/− ≈ 25 pS;
2,185 events pooled from nine cells). (c) Kinetic
analysis of the 18-pS and 25-pS channel classes from both +/+ and
−/− mice showed that the fast components of both classes were
similar in the +/+ and −/− mice. However, the +/+ channels each
contained two longer-duration components that were missing from the
−/− classes. Mean τ values ± SEM are reported in the
text.