EFFECT OF HIGH-PEAK-POWER MICROWAVE PULSES ON ISOLATED NERVE FUNCTION

Isolated frog sciatic nerves were exposed to high-peak-power microwave pulses (915 MHz) with the help of a stripline slot irradiator. The ne rves were stimulated using twin pulses separated by a 6-ms interval at a repetition rate of 50 pairs/sec. Microwave pulses (0.5 ms or 3 ms w idth, peak specific absorption rate 33-72 and 6-13 kW/kg) were either synchronized with stimuli in various manners or were asynchronous (50 p.p.s.). Nerve heating during exposure was within 1.5-2.7-degrees-C. T he exposed nerves underwent faster decrease of compound action potenti al (CAP) amplitude and tracing integral; the effect was microwave-spec ific since the equivalent conventional heating of nerve produced the o pposite changes. The magnitude of the effect had little, if any, corre lation with the intensity of the microwave pulses and their phasing wi th the nerve action potential. CAP onset and peak velocities as well a s nerve refractivity were not affected by microwave exposure.