title: High frequency discharges in sensory nerves following ischemia.
abstract: The effects of ischemia and recovery from ischemia on afferent discharges recorded from dorsal root filaments were assessed in anesthesized cats. During ischemia produced by cross-clamping the lumbar aorta, some of the hindlimb afferents originating in muscle spindles exhibited a sustained high frequency discharge of 120--160 Hz, the so-called "explosion." During recovery from ischemia, nerve discharges appeared in previously inactive dorsal root afferent nerve fibers not of muscle spindle origin. The post-ischemic high frequency discharges appeared in bursts of action potentials at frequencies of 200--500 per second, with 6--32 spikes per burst; the bursts recurred at intervals of 120--600 msec. The nerve fibers exhibiting post-ischemic bursts could not be activated by muscle stretch, muscle tension, palpation, or tactile skin stimulation prior to or during the ischemia. No post-ischemic burst discharges could be detected in analogous experiments with the sural nerve. Intermediate size fibers from normal cutaneous and muscle mechanoreceptors were eliminated as possible origins of the post-ischemia activity. Possible sources include dorsal root ganglion cells or fibers whose sensory endings lie in deep structures such as the walls of the larger blood vessels.
mesh_terms: D000818:Animals; D002415:Cats; D005073:Evoked Potentials, Somatosensory; D005727:Ganglia, Spinal / Q000503:physiopathology*; D006614:Hindlimb / Q000098:blood supply*; D007511:Ischemia / Q000503:physiopathology*; D008465:Mechanoreceptors / Q000503:physiopathology; D009470:Muscle Spindles / Q000503:physiopathology; D009132:Muscles / Q000098:blood supply*; D012584:Sciatic Nerve / Q000503:physiopathology; D012677:Sensation / Q000502:physiology*; D013116:Spinal Cord / Q000503:physiopathology; D013497:Sural Nerve / Q000503:physiopathology; D009435:Synaptic Transmission