Accession Number : AD0727981


Title :   X Ray-Induced Transient Changes in Nerve Characteristics.


Descriptive Note : Scientific rept.,


Corporate Author : ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD


Personal Author(s) : Gallagher,P. N. , Jr. ; Levich,C.


Report Date : JUN 1971


Pagination or Media Count : 28


Abstract : The immediate effects of x rays on nerve excitation and conduction characteristics were studied. Excised sciatic nerves of frogs (Rana catesbeiana) were given a series of 10- to 90-second 300 kVp x irradiations at 2750 or 1450 rads/minute. Before, during, and after irradiation the nerves were submaximally excited by identical electrical stimuli 10 times per second, and the resulting monophasic compound nerve action potentials (NAP) and nerve conduction velocity were analyzed. A transient increase in amplitude of the NAP was detectable within 3 seconds of the beginning of irradiation; NAP amplitudes returned to stable, near preirradiation values shortly after termination of each exposure. Doses of approximately 4000 rads resulted in easily detectable transient increases in nerve conduction velocity. It is suggested that these changes are a result of a lowered threshold for electrical stimulation (INCREASED EXCITABILITY) and an increased initial rate of change of sodium conductance across the nerve membrane. Further, the increased NAP amplitudes and conduction velocities were accentuated as a nerve was repeatedly irradiated implying that damage remained from previous exposures which was not clearly evident without the added stress of subsequent irradiation. (Author)


Descriptors :   *NERVES, RADIATION EFFECTS, AMPHIBIANS, SODIUM, WOUNDS AND INJURIES, ELECTROPHYSIOLOGY.


Subject Categories : RADIOBIOLOGY


Distribution Statement : APPROVED FOR PUBLIC RELEASE