Smooth muscles in vivo and in vitro. Chapter 3.6

A review is presented of reports of the effects of radioprotective agents on smooth muscles. A distinction must be made between the reactions of smooth muscle fibres in isolated organs, and reactions registered in situ which include the possibility of some compensatory mechanism (catecholamine secretion, histamine release, etc.). Studies have been made of the reactions of various muscles in different species, and the results show that, as a whole, non-vascular smooth muscle layers react only slightly to radioprotective agents. The reactions are of minor importance in the development of the general intoxication. Cysteamine as an aliphatic amine cannot be included among agents having a sympathomimetic action. Smooth muscle reactions in whole animals result from a complex mixture of direct action stimulation or inhibition of central origin, disturbances of ganglionic transmission and interference with homeostatic processes, but there are no significant direct effects of sulphur-containing radioprotective agents in non-vascular smooth muscle. (U.K.)