Effect of ischemia and cooling on the response to high frequency stimulation in rat tail nerves

In normal rat tail nerves the effect of temperature and ischemia on the res ponse to long-term high frequency stimulation (HFS) (143 Hz) was studied. T he effect of temperature was studied in two consecutive tests at 14 degrees C and 35 degrees C. Prior to the HFS the peak-to-peak amplitude (PP-amp) o f the compound nerve action potential was 139 +/- 20 mu V (mean +/- SD) and 127 +/- 37 mu V at 35 degrees C and 14 degrees C, respectively (NS). After 15 min of HFS the PP-amp was reduced to 45.3 +/- 20.5% of baseline level a t 14 degrees C as compared with 80.8 +/- 10.2% at 35 degrees C (p < 0.001). Applying ischemia to the rat tail, an additional fall of the PP-amp was se en after 15-20 min of HFS at both low (20 Hz) and high (143 Hz) stimulation frequencies. In conclusion, ischemia and cooling result in an impaired abi lity to transmit high frequency impulses.