Search for Immediate Effects of X-Radiation on Frog Nerve-Muscle Preparations

Abstract

For more than thirty years there have been reports of the effects of ionizing radiations on nerves and muscles. In the U. S. S. R., in particular, there has been considerable attention paid to these problems, but workers in other countries have contributed occasional important studies. Since such reports form the basis on which we designed our program and since there has been no recent adequate account of them other than by Russian-speaking authors, we review briefly a selection of recent published work to illustrate the considerations involved. Much of the Russian work in the field has been summarized in papers given at the second Geneva Conference on the Peaceful Uses of Atomic Energy (1-5). Most of the relevant studies mentioned in these papers concern changes in conditioned reflexes in various animals after whole-body or partial-body irradiation. For example, secretion of saliva in response to conditioned and unconditioned stimuli before and after whole-body irradiation with 250 r was studied by Fadeeva, Kurtsin, and Golovskii (quoted by Gorizontov, 4) in dogs with Pavlov stomachs; hypo- and hypersecretion were observed after irradiation, depending on the conditions. Yanson (quoted in 4) studied the increased rate of respiratory rhythm associated with a defensive conditioned reflex elicited in rabbits; he found that after 500 r to the whole body or to the head of the rabbit the rate fell sharply and remained low for some days. Many other such results are also referred to in the papers cited. Some studies have been made of the electrical activity of the higher nervous centers after irradiation. Lee et al. (6) stimulated the sciatic nerve of cats to evoke a cerebellar response which they recorded with electrodes touching the pia mater; the amplitude of the response began to diminish after a dose of about 6 kr had been given, and the effect was severe after 10 kr. The response continued to fall for 10 to 30 minutes after irradiation had ceased. Various changes after irradiation have also been reported in electroencephalograms (2, 7).