[Effect of microwave irradiation and temperature on the spontaneous impulse activity of the ventral spinal roots in the frog].

The rate of spontaneous aperiodic activity in ventral roots of isolated, sagittally hemisected frog spinal cord varied from several hundreds up to 4-6 thousand spikes per minute. This rate was the lowest at temperature of 7-11 degrees C; at higher or lower temperatures the activity augmented. Short-term reactions occurred with changes in the temperature: while heating the cord, the activity decreased, and during cooling it intensified. Microwave irradiation (6.45 GHz, specific absorption rates: 0.1, 0.4 and 2 W/g, action duration: 5 min) had no influence on the spike rate if the temperature remained constant. VHF-heating of the preparation and elevation of the superfusing fluid temperature caused the same changes in the activity. The results obtained evidence for the thermal mechanism of neurotropic influence of microwaves.