Effect of High-Peak-Power Microwave Pulses on Isolated Nerve Function

Abstract

Isolated frog sciatic nerves were exposed to high-peak-power microwave pulses (915 MHz) with the help of a stripline slot irradiator. The nerves were stimulated using twin pulses separated by a 6-ms interval at a repetition rate of 50 pairdsec. Microwave pulses (0.5 ms or 3 ms width, 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°C. The exposed nerves underwent faster decrease of compound action potential (CAP) amplitude and tracing integral; the effect was microwave-specific since the equivalent conventional heating of nerve produced the opposite changes. The magnitude of the effect had little, if any, correlation with the intensity of the microwave pulses and their phasing with the nerve action potential. CAP onset and peak velocities as well as nerve refractivity were not affected by microwave exposure.