THE PHARMACOLOGICAL ACTION OF PROTOCATECHYL-TROPEINE. 285 



All the substances previously investigated which have been shown to paralyse 

 temporarily the respiration are quaternary bases. The tertiary bases corresponding to 

 these did not, where tried, affect the respiration. Protocatechyl-tropeine, however, is a 

 tertiary base, and chemically has nothing in common with the other substances pro- 

 ducing the same respiratory effect. But it possesses another physiological action 

 common to many of them, namely, the power of paralysing the motor nerve endings to 

 voluntary muscle. It is questionable, however, if this connection is more than a co- 

 incidence, since trimethyl-ammonium chloride, triethyl-ammonium chloride, and 

 tetraethyl-ammonium chloride, which paralyse motor nerve endings, have no paralysing 

 action on the respiratory centre ; * and the papaverin bases which do produce re- 

 spiratory paralysis do not paralyse motor nerve endings. 



Summary. 



Protocatechyl-tropeine paralyses the vagal endings in the heart, but is much less 

 powerful than atropine, or even homatropine. 



It depresses muscular activity, especially in frogs, and interferes with the con- 

 ductivity of motor nerves, or more probably the myo-neural j unctions, in rabbits. 



In certain doses, it paralyses temporarily the respiration, and causes a gradual fall 

 of blood-pressure ; but the two effects are not apparently correlated. In cats, a rise of 

 blood-pressure sometimes occurs, owing to the paralysis of the vagal endings. 



The temporary stoppage of the respiration is due to paralysis of the respiratory 

 centre, and not to a peripheral action. 



No evidence indicating separate pharmacological actions of the two component 

 groupings of the compound was obtained. 



* Tappeiner, loc. cit. 



TRANS. ROY. SOC. EDIN, VOL. XLVII. PART II. (NO. 12). 43 



