The Physiological Action of Choline and Neurine. 



93 



Physiological Action of Neurine. 



The doses employed varied from 1 to 5 c.c. of a 0*1 per cent, solu- 

 tion. These were injected intravenously. 



Neurine produces a fall of arterial pressure, followed by a marked 

 rise, and a subsequent fall to the normal level. Sometimes, especially 

 with small doses, the preliminary fall may be absent. Sometimes, 

 especially with large doses, by which presumably the heart is more 

 profoundly affected, the rise is absent. 



The effect of neurine on the heart of both frog and mammal is much 

 more marked than is the case with choline ; in the case of both choline 

 and neurine, the action on the frog's heart is antagonised by atropine. 



The slowing and weakening of the heart appear to account for the 

 preliminary fall of blood pressure ; in some cases this is apparently 

 combined with a direct dilating influence on the peripheral vessels. 



The rise of blood pressure which occurs after the fall, is due to the 

 constriction of the peripheral vessels, evidence of which we have 

 obtained by the use of oncometers for intestine, spleen, and kidney. 



After the influence of the central nervous system has been removed 

 by section of the spinal cord, or of the splanchnic nerves, neurine still 

 produces its typical effects. 



After, however, the action of peripheral ganglia has been cut off by 

 the use of nicotine, neurine produces only a fall of blood pressure. 

 It therefore appears that the constriction of the vessels is due to the 

 action of the drug on the ganglia; in this, it would agree with nicotine, 

 coniine, and piperidine. 



Section of the -< T agi produces no influence on the results of injecting 

 neurine. 



In animals anaesthetised with morphine and atropine, injection of 

 neurine causes only a rise of blood pressure, which is accompanied with 

 constriction of peripheral vessels. 



Xeurine produces no direct results, so far as we could ascertain, on 

 the cerebral blood vessels. 



Neurine is intensely toxic to nerve-trunks (Dr. Waller and Miss 

 Sowton). 



It produces a marked effect on the respiration. This is first greatly 

 increased, but with each successive dose the effect is less, and ultimately 

 the respiration becomes weaker, and ceases altogether. The animal 

 can still be kept alive by artificial respiration. 



The exacerbation of respiratory movements will not account for the 

 rise of arterial pressure ; the two events are usually not synchronous, 

 and an intense rise of arterial pressure (due, as previously stated, to 

 contraction of peripheral blood vessels) may occur when there is little 

 or no increase of respiratory activity or during artificial respiration. 



As confirmatory of Cervello's statement that neurine acts like 



