Excitatory and inhibitory components of somato-sympathetic reflex

Abstract

In cats anesthetized with chloralose it was confirmed that electrical stimulation of somatic nerves evoked a reflex volley (late response) followed by a transient inhibition of the spontaneous discharge (silent period) in the sympathetic postganglionic renal nerve. The thresholds for both the late response and silent period were in the same range, from 1.2 to 1.5 times the threshold for the fiber excitation in the superficial radial nerve, and from 2.5 to 3.0 times in the hamstring and sciatic nerves. The independent occurrence of the silent period from the late response was demonstrated in recovery tests. Furthermore, lesions in the dorsal surface area of the medulla oblongata selectively abolished or greatly depressed the late response, whereas lesions in the ventral medullary reticular formation selectively abolished or greatly depressed the silent period.