PHARMACOLOGICAL ACTION OF TETKA-ALKYL-AMMONIUM COMPOUNDS. 25 



after tetra-raethyl-ammonium chloride. They do not appear to have been noticed by 

 Santesson and Koraen,* and they were not observed in my experiments with winter 

 frogs. On the contrary, I found that this substance would inhibit or prevent the 

 fibrillary contractions produced by tetra-methyl-ammonium chloride. 



They occurred, however, to a slight extent when an isolated muscle was steeped in 

 certain concentrations of tetra-methyl-ammonium chloride, and I have frequently seen 

 fibrillary twitchings in rabbits occurring both spontaneously and as the result of 

 stimulating a nerve. To this point I shall return in a later communication. 



vj\rumruTj\nnnr\j\rL r \riJ\^ 



Fig. 6. — Effect of 1 ing. tetra-methyl-ammonium chloride intravenously on respiration and blood-pressure of 

 etherised rabbit. Weight 1650 g. Letters as in previous figures. 



Effect on Respiration. 



In anaesthetised animals the most interesting effect on the respiration is the 

 temporary paralysis which follows the intravenous injection of certain doses of this 

 drug. The effect is most typically seen in rabbits, and is shown in fig. 6. The effect 

 of a larger dose on a cat is seen in fig. 1. As will be observed, the respiration ceases 

 or almost ceases a few seconds after the injection of the substance, and some seconds 

 later recommences, at first slightly and somewhat less frequently than normally, and 

 then with increasing depth and frequency until the normal is reached. The dose 

 required to produce the effect is 0'5 to 1 mg. p. kg. body- weight intravenously, and it 

 is necessary to make the injection moderately quickly (in about five seconds) in order to 

 obtain for a sufficiently brief interval the proper concentration of the substance in the 



* hoc. cit., p. 220. 

 TRANS. ROY. SOC. EDIN, VOL. L. PART I. (NO. 2). 4 



