Single ionic channels induced by palytoxin in guinea‐pig ventricular myocytes

Open Access
Publisher Website
Google Scholar
Abstract
1 Mechanisms of palytoxin-induced ion permeability were examined in isolated single ventricular cells of guinea-pig under whole-cell-attached patch clamp conditions. 2 Palytoxin (1–2 × 10−11 m, dissolved in Tyrode solution and put in the patch electrode) induced an elementary current flowing through single channels. Direction of the current was inward and the amplitude was 0.65 ± 0.03 pA (mean ± s.e. mean) at the resting membrane potential. The amplitude increased linearly with membrane hyperpolarization and decreased with depolarization; the single channel conductance was 9.5 ± 0.5 pS. 3 Palytoxin-induced single channel current was resistant to tetrodotoxin (5 × 10−5 m) or cobalt ions (2 × 10−3 m) and was observed under Ca-free conditions. However, no channel current was induced by palytoxin (10−11-10−9 m) dissolved in Na+-free, choline-Tyrode solution. 4 Palytoxin also induced single channel currents in Na+-free, NH+4-, Li+- or Cs+-Tyrode solution, and the slope conductances were 16.5 ± 1.6 pS, 9.2 ± 0.7 pS and 11.0 ± 0.7 pS, respectively. 5 These results indicate that palytoxin forms a new type of ionic channel with unique ion selectivity and gating behaviour.

This publication has 34 references indexed in Scilit: