Differential suppression of charge movement components by gluconate in cut twitch fibres of Rana temporaria.

1. Charge movement was studied in cut twitch fibres of Rana temporaria using a double Vaseline-gap voltage-clamp technique. 2. Replacement of Cl- by gluconate in the external solution reduced the magnitude of the early current component (I beta) substantially but affected the magnitude and slowed the kinetics of the hump current component (I gamma) slightly. 3. The early (Q beta) and hump (Q gamma) charge components in the gluconate solution were 11.8 +/- 2.3 and 88.0 +/- 4.8% (mean +/- S.E.M., n = 9), respectively, of those in the Cl- solution. 4. These results suggest that Q beta cannot be a precursor of Q gamma. Moreover, since fibres bathed in a gluconate solution can release calcium, Q beta is probably not involved in triggering calcium release.