Effects of rapid temperature changes and large fields on electrical parameters of frog skin

Measurements of slope and chord resistance, capacitance and total potential were determined in experiments in which the temperature was rapidly changed from room temperature to 8°C and in experiments in which the total skin potential was rapidly varied throughout the range of ±250mv. For the sodium experiments sodium sulphate was used to bathe both sides of the skin. Potassium replaced sodium in the potassium experiments. Electrical parameters were determined from the analysis of the voltage-time responses to step currents. Temperature changes were accomplished by rapid placement of bathing solutions of differing temperatures. All control functions, data acquisition and analysis were performed automatically by a digital computer and its associated peripheral equipment. The results obtained were as follows: 1) Difference in the time-courses (after a temperature change) of the sodium of potassium resistance data indicates the existence of separate diffusion mechanism for these two ions. The data suggest that complexing may be involved in the sodium diffusion process. 2) Sodium resistance has a large voltage dependence. Resistance changes as his as six to one were observed over the range of ±250mv. Resistances increased as the membrane potential increased. 3) Apparent anomalous impedance effects exhibit no detectible changes in slop conductance. 4) The measured capacitance values exhibited marked positive temperature coefficient. A model assumes temperate dependent rate constants associated with the rotation barriers of large dipole molecules. 5) In the sodium state, the total skin potential reduced for to 25 percent for a 14°C reduction in temperature. The decrease was immediate and often remained constant until the control temperature was restored.