Seasonal changes in the properties of frog. End-plate channels

The properties of the acetylcholine (ACh)-activated channel at the frog neuromuscular junction were studied using a two-microelectrode voltage clamp. The reversal potential was determined by interpolation of the ACh-induced current vs. voltage relation, while the single-channel conductance and the mean channel lifetime were calculated from fluctuation analysis of the mean ACh-induced end-plate current. Seasonal changes were observed in some of the measured parameters. While the reversal potential and the mean channel lifetime remained constant throughout the year, the single-channel conductance did not. The single-channel conductance was on the average 35% higher in the winter than in the summer. This effect could have survival value for hibernating frogs.