PHARMACOLOGICAL ACTION OF TETRA-ALKYL- AMMONIUM COMPOUNDS. 497 



rapidity of the contracture, and it is evident from this and the succeeding stimulus 

 that there is no diminished irritability during the progress of the contracture ; but 

 notwithstanding that the contracture is well below the maximal, the subsequent 

 stimulations show considerable diminution followed by recovery. 



The contracture obtained from the gastrocnemius differs in some respects from 

 that obtained from the sartorius in being less extensive and more prolonged. More- 

 over, the diminished irritability of the muscle occurring during relaxation in the 

 case of the sartorius, was not observed when the gastrocnemius was employed. The 

 differences are partly due to differences in bulk of the two muscles and consequent 

 differences in the time in which the whole of the muscle-fibres of the respective 

 muscles are affected by the environing solution ; for if the rapidity of penetration of 

 the tetra-methyl-ammonium chloride solution into the sartorius be delayed, the 

 contracture produced assumes the type obtained from a gastrocnemius. Thus if the 



K»»»MM»»M»»»l»»»»»»»»»M«. ■,■■■■■, M1»»» 



Fig. 9.— Similar experiment to that shown in previous figure, but with 0-2 per cent, tetra-methyl-ammonium chloride and 

 muscle previously immersed in Ringer's fluid in place of 0'6 sodium chloride. Secondary coil at 14 cm. Time in ten 

 seconds, x f . 



sartorius be separated for a short distance only at its lower end, and the adjacent 

 muscles cut at their distal extremities be excised with it, the curve obtained by 

 immersing the preparation in tetra-methyl-ammonium chloride solution is very 

 similar to that obtained in the case of the gastrocnemius, and the effect of stimulat- 

 ing the sartorius indirectly through the sacral plexus is similar to that produced by 

 stimulating indirectly the gastrocnemius. 



When the gastrocnemius is periodically stimulated directly no diminution of the 

 irritability of the muscle, if allowance be made for the state of contraction, is seen 

 during the continuance of the contracture ; but, as Boehm # pointed out, the duration 

 of the contracture is shortened by the stimulations (cf. fig. 10). If isotonic solutions 

 of tetra-methyl-ammonium chloride are employed, the muscle quickly becomes 

 un irritable to moderately strong faradic stimuli (fig. 10), but it may retain a slight 

 degree of irritability to very strong stimuli for some hours. With a concentration 

 of tetra-methyl-ammonium chloride one-fourth this strength, considerable irritability 



* Arch.f. exp. Path. u. Pharmalc., lviii. p. 267 [1908]. 

 TRANS. ROY. SOC. EDIN., VOL. L. PART II. (NO. 17). 



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