Figure 4.

Effect of apamin (300 nM) in the presence of atropine. (A and B) Time course of effects of apamin, a small conductance K⁺ channel blocker, on the clasp and sling muscle, respectively. (C(a) and (b) and D(a) and (b)) Snapshots of IJPs before and 10 min after apamin in clasp and sling muscle, respectively. (C(c) and D(c)) Overlay of IJPs before and after apamin. Apamin depolarized resting membrane potential and decreased the IJP amplitudes in both clasp and sling muscles. However, no significant effect was observed on the long-lasting phase of the biphasic IJP in clasp muscle. IJP, inhibitory junction potential.