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XII. — The Pharmacological Action of Protocatechyl-Tropeine.* 

 By Professor C. R. Marshall. 



(MS. received November 20, 1909 Read June 21, 1909. Issued separately January 7, 1910.) 



Protocatechyl-tropeine is one of a series of new tropeines investigated primarily 

 with the object of determining the difference in pharmacological action between a 

 lactone and the corresponding hydroxy -acid, f Its constitution is shown in the 

 following formula : — 



HC 

 HC 



COH 

 C-OH 



CrL 



-CH- 



-CH 



CH 

 CCOO-HC 



NCH Q 



CH„ CH- 



-CH 



Like most other tropeines, it paralyses the vagal nerve endings in the heart. It 

 also diminishes the irritability of voluntary muscle and its myo-neural junctions, 

 and paralyses the respiratory centre. 



Action on the Respiration. 



When O'Ol g. protocatechyl-tropeine hydrochloride is injected into the external 

 jugular vein of an anaesthetised rabbit or cat the respiration is rapidly paralysed (fig. l). 

 It generally ceases within ten seconds of the commencement of the injection, and may 

 or may not recommence spontaneously. If it does not recommence, artificial respiration 

 performed for ^-1 min. will fully re-establish it. After larger doses (e.g. 0'02 g.) 

 it may be necessary to resort to short periods of artificial respiration three or even four 

 times before the respiration is permanently established, and then it may remain 

 somewhat shallower than at first. (In one animal in which the uncut sciatic or crural 

 nerve was being stimulated at intervals, the respiration restarted spontaneously after 

 the injection of this dose, but it failed again later.) Doses of 0*005 g. intravenously 

 may also paralyse the respiration, but it recommences with a shorter period of artificial 

 respiration than is the case after larger doses. Smaller doses produce only shallower 

 and less frequent respirations, the effect being roughly proportional to the dose. The 

 smallest effective dose is 0"001 g. intravenously. 



* I am indebted to Mr H. A. D. Jowett, D.Sc, for his kindness in providing me with this substance. Its 

 preparation and characters have been described by him in conjunction with Mr Hann (Trans. Chem. Soc, vol. 89, 

 p. 364). 



t Arch. f. exp. Path. u. Pharm., 1908, Supplem. Bd., p. 389. 



TRANS. ROY. SOC, EDIN., VOL. XLTII. PART II. (NO. 12). 41 



