Sympathetic single axonal discharge after spinal cord injury in humans: activity at rest and after bladder stimulation.

Abstract

Clinical experimental mechanistic study. (1) To determine in three spinal cord-injured patients whether individual muscle sympathetic nerve fibres below the level of the spinal lesion display spontaneous activity. (2) To determine in these patients if individual sympathetic vasoconstrictor fibres show a prolonged discharge following a bladder stimulus. University hospital in Gothenburg, Sweden. Microneurographic recordings of action potentials from individual muscle nerve sympathetic fibres in a peroneal nerve. Recordings of skin blood flow and electrodermal responses in a foot. In all patients, there was sparse ongoing spontaneous impulse traffic in individual sympathetic fibres. Brisk mechanical pressure over the urinary bladder evoked a varying number of action potentials in individual fibres, but the activity was brief and did not continue after the end of the evoked multiunit burst. Prolonged discharges in individual sympathetic fibres are unlikely to contribute to a long duration of blood pressure increases induced by brief bladder stimuli.