IMMEDIATE REACTIONS OF NERVES AND MUSCLES 

 TO IONIZING RADIATION 



O. HUG AND H. J. SCHLIEP 



Strahlenbiologisches Institut der Universitdt Miinchen und Institut fiir Strah- 

 lenschutzforschung der Geselhchajt fiir Kernforschung , Neuherberg bei 



Miinchen, Germany 



SUMMARY 



In contrast to the peripheral motoric nerves and striated muscles but similar 

 to smooth muscle organs of vertebrates nerve-muscle preparations of worms 

 show immediate partially reversible reactions to relatively low doses of X-rays 

 as changes in motility and contraction. Nerve-muscle preparations are more 

 sensitive than isolated muscles. Remarkable is the strong dose-rate dependence 

 of these functional changes. There are some indications that the effects are due 

 to reversible changes of cell permeability under and shortly after irradiation. 



INTRODUCTION 

 On earlier occasions (Hug, 1958, 1960) I have had the pleasure of pre- 

 senting a film showing that many lower animals react to ionizing radi- 

 ation with reflex-like motions : snails retract their tentacles ; clams re- 

 tract their gills and close their shells ; actiniae incline and shorten their 

 tentacles and subsequently the whole body of the animal is retracted 

 and shortened. The leech shows peristaltic contractions, writhes 

 violently and finally moves out of the X-ray beam. The small sea 

 urchin, when irradiated under water, retracts its feet and moves out 

 of the irradiated area too. A crustacean, the barnacle, stops the rhyth- 

 mic opening and closing of its cover and the grasping motions of 

 its cirripedia. Many insects, such as ants, spiders and fleas, show 

 characteristic behavioral changes imder X-irradiation. The same effects 

 as with 50 kV X-rays have been produced by a-rays in some of these 

 animals. Those of these effects which we have investigated quantita- 

 tively show a characteristic dependence on dose and dose-rate (Hug, 

 1959). In each species, a minimum dose-rate is necessary to produce 

 the effects under contumous irradiation. x\bove this threshold the 

 minimum irradiation time decreases with increashig dose-rate. The 

 product of dose-rate and necessary irradiation time is not constant over 

 the whole range of dose-rate. In this respect there exists at least an 



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