88 



Scientific Proceedings (48). 



64 (673) 



The stimulation of nerve-endings in muscle and the theory of 

 receptive substances. 



By MARY WHITALL WORTHINGTON. 1 



[Physiological Laboratory of the Johns Hopkins University.] 



Langley has shown that the stimulating action of nicotine 

 upon muscle is prevented by curare and that this antagonism is 

 exhibited also in muscles in which the nerve fibers have been 

 removed by degeneration. This and other facts have led him to 

 formulate the hypothesis of special receptive substances present 

 in the muscle upon which these drugs and other chemical stimuli 

 exert their action, and furthermore he ventures the generalization, 

 in contradiction of the usual belief, that "in no case do chemical 

 substances have a special action on nerve-endings." 



The series of experiments here reported were made at the 

 suggestion of Dr. J. W. Warren to test the above hypothesis. The 

 gastrocnemius muscle of the frog was used and its reactions were 

 studied after immersion in solutions of sodium sulphocyanide and 

 potassium sulphocyanide. The following results were obtained. 



1. Action of potassium sulphocyanide. — This salt was used in 

 hypertonic solutions (2 per cent. KCNS made up in a Ringer's 

 mixture) and in isotonic solutions (1 per cent. KCNS in water). 

 In both cases solutions of this salt caused an immediate rapid 

 primary contraction followed by a prolonged contracture. This 

 effect was not removed by the action of curare nor by the de- 

 generation of the motor nerve fibers. It was obtained also by 

 the action of other potassium salts, e. g., potassium chloride — and 

 must be considered as an instance of the "potassium contraction" 

 described by other authors. The potassium ions may act upon 

 the supposed receptive substance, but evidently their effect does 

 not depend upon the presence of the nerve terminals. 



2. Action of sodium sulphocyanide. — This salt was used also in 

 hypertonic and isotonic solutions as in the case of the potassium 

 sulphocyanide. In hypertonic (2 per cent.) solutions it caused a 

 large primary contraction followed by a condition of contracture 

 and by frequent isolated or grouped twitches of a coordinated or 



1 Deceased. Presented by W. H. Howell. 



