Excitability characteristics of the A- and C-fibers in a peripheral nerve

Abstract The saphenous nerve of the cat was stimulated with square pulses, triangle waves, sine waves, and haversine waves of varying intensities and durations. We found that haversine waves, with the anode proximal to the cathode in relation to the recording electrode, were most effective in producing “break” responses. At a given intensity and duration of the haversine waves for stimulation, only the response of C-fibers in the nerve was recorded. The strength/duration curves show that the rheobase of the C-fibers was 0.033 ma; and of the A-fibers, 0.0166 ma. The C-fibers had a chronaxy of 1.5 msec; the A-delta fibers, 0.45 msec; and the A-beta fibers, 0.020 msec. The average conduction velocity of the C-fibers was 0.92 m/sec; of the A-delta fibers, 11.2 meters per second; and of the A-beta fibers, 85.8 m/sec. The temperature of the nerves in the experiment was 29–30 C.

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