Electrophysiologic studies of penile mechanoreceptors in the rat

Abstract The neural activity of afferent fibers in the dorsal nerve of the penis was studied in 16 barbiturate-anesthetized rats. Sixty-one single units responsive to mechanical stimulation were isolated. Each receptor was tested for critical displacement, force, and velocity thresholds as well as its sinusoidal stimulation frequency-following characteristics and fiber conduction velocity. Based on adaptation responses to sustained mechanical stimuli, 36 of the 61 fibers were classified as rapidly adapting (RA) units and 25 as slowly adapting (SA) units, whereas previous workers did not find any slowly adapting receptors. We believe our ability to find SA units is due to mechanical and thermal stabilization of the penis and to our use of a wellcontrolled mechanostimulator.