298 O. HUG AND H. J. SCHLIEP 



Our observations of these immediate reactions of nerves and muscles 

 of lower animals are in strong contrast to the well known radioresistance 

 of isolated pei'ipheral nerves and striated muscles of Amphibiae and 

 mammals (Bergeder, 1955, 1958; Bergeder and Hockwin, 1960; Gerstner 

 et ah, 1954; Darden. 1960). Only Bacq et al., (1949) once reported that 

 X-rays and j8-rays of 32p produce immediate reversible contractions of 

 the frog rectus. 



One may conceive that this discrepancy is due to differences in 

 methods, because the other authors usually recorded the effects a 

 certain time after irradiation only. However, when we irradiated muscles 

 and nerve-muscle preparations of the frog under the conditions de- 

 scribed al)Ove no immediate reversible changes in tonus and motility 

 could be registered. Only under very high dose-rates did the tonus rise 

 slowly under and after ii'radiation, and the dose-eflfect-relationship is 

 in agreement with those reported in the literature. 



On the other hand, as mentioned already, various — if not all — 

 smooth muscle organs of cold blooded animals and mammals react in a 

 similar fashion to ionizing radiation as nerve-muscle preparations of 

 lower animals. We have been able to confirm, in part, numerous earlier 

 and long neglected observations (Swan, 1924) of radiation-induced 

 changes in motion and tonus of smooth muscle organs under control 

 of the autonomous nervous system, such as stomach, intestine, uterus, 

 lung and blood vessels, and we observed that these effects depend on 

 dose-rates comparable to those of the experiments described above. 

 The elucidation of the differences in reaction of various types of muscles 

 to ionizing radiation would contribute very much to our understanding 

 of the action mechanism of radiation on the one side and of muscle 

 physiology in general on the other. The immediate reactions of certain 

 tissues and organs and their role in acute radiation effects on higher 

 organism seem to deserve particular attention in future radiobiological 

 studies. They may serve to call our attention more and more to the 

 problems and methods of general physiology, which at times appears to 

 have been neglected in radiobiological research. 



It should be taken into consideration whether or not short-lived 

 changes of permeability may occur not only in irradiated excitable 

 cells such as nerves and muscles but also in other cell types. A few re- 

 marks made in this symposium by Alexander, Hollaender, Errera, 

 Holmes and Passynsky can be taken as confirmations of the assumption, 

 that some early radiation effects on various cells may be attributed to 

 changes in their permeability. 



