64 THE SIMPLER NATURAL BASES 



Other synthetic substances allied to choline have been described by Schmidt [1891, 1904, 

 I, 2], Malengreau and Lebailly [1910, under homocholine], Mengefign], and Berlin [1910, 

 I, 1911, under homocholine] who gives further literature. 



The action Q{ neurine shows a general resemblance to that of choline 

 and muscarine, and like these, it is antagonised by atropine. To 

 rabbits it is 10-20 times as toxic as choline (Brieger [1885, i, p. 39]) ; 

 on subcutaneous injection the lethal dose is about 40 mg. per kilo. 

 Cats are more susceptible and react violently to doses of a few milli- 

 grams. The effects are profuse salivation, dyspnoea, an initial accel- 

 eration and then a retardation of the heart beat and death in diastole ; 

 the intestine is stimulated to violent peristalsis ; there is often myosis 

 in rabbits and always in cats. Atropine is a powerful antidote. In 

 frogs there is a curare-like paralysis and diastolic arrest of the heart's 

 action, after injection of 1-2 mg. into the dorsal lymph sac. 



Waller and Sowton [1903] studied the effect of neurine and other 

 bases on isolated nerves and on the excised heart of the frog ; neurine 

 was the most toxic, rather more than muscarine, and very much more 

 so than choline. 



Lohmann [1911] finds that neurine in doses of 10 mg. first lowers 

 the blood pressure of rabbits and then raises it. The general effect of 

 neurine on the blood pressure is to produce a rise after a preliminary 

 fall (Mott and Halliburton [1899]; Pal [1911]). Minute doses, of 

 TTJW m g-> mav k either pressor or depressor. The rise of blood 

 pressure is due to constriction of the peripheral vessels (compare 

 Samelson [1911] who found, by the Laewen-Trendelenburg method, 

 that neurine acts on the frog's limb in a dilution of I : 800,000). 

 The physiological action of synthetic bases allied to neurine has been 

 described by Schmidt [1891, 1904, i]. 



Natural and Synthetic Muscarines and their Physiological 



Action. 1 



Muscarine is the name given by Schmiedeberg and Koppe [1869] 

 to an extremely poisonous base which they obtained from Amanita 

 muscaria (the Fly Agaric). Very small amounts arrest the frog's heart 

 in diastole and the action is antagonised by atropine. 



Other bases of somewhat similar composition and similar physio- 

 logical action have been obtained synthetically, and one of these was at 

 one time considered to be identical with natural muscarine. It seems 

 certain, however, that this is not so. 



1 Compare the important addendum on p. 68. 



