THE PHARMACOLOGICAL ACTION OF PROTOCATECHYL-TROPEINE. 279 



On immersing a nerve-muscle preparation (gastrocnemius) in a 1-1000 solution of 

 protocatechyl-tropeine hydrochloride in 0*6 per cent, sodium chloride and stimulating 

 (one Daniell's cell) the nerve and muscle alternately every three minutes, the 

 contractions were found to fall with the same regularity in each case, and both muscle 

 and nerve became inexcitable forty-five minutes after immersion. 



In a rabbit no muscular paresis was observed after 062 g. p. kg. intraperitoneally. 

 Depression but not always paralysis of the nerve endings is obtained after intravenous 

 administration to an anaesthetised animal. This is shown in fig. 4. The rabbit was 

 prepared in the manner described, the right crural nerve was laid bare, and a hook was 

 put into the right foot and connected by means of a thread working over pulleys to a 

 weighted lever. After a practically constant effect had been obtained from stimulation 

 of the nerve (one accumulator cell; secondary coil 12 cm.), 001 g. protocatechyl- 

 tropeine hydrochloride was injected into the right facial vein. The contraction of the 

 muscles produced by stimulation of the nerve gradually diminished until it disappeared 

 two minutes after the commencement of the injection. Two and a half minutes later 

 the limb muscles again responded to stimulation of the nerve, but the contractions did 

 not assume their previous (normal) form until ten minutes after the injection of the 

 drug. The tracing reproduced records a second injection of the drug ; the same dose 

 was administered at 11.19 and produced a similar effect. 



In a second experiment, in which both the right crural and sciatic nerves were 

 exposed, it was found that the muscles, when stimulated directly, contracted in the 

 neighbourhood of the electrodes at a time when the nerves were inexcitable. It would 

 seem, therefore, that in the rabbit the nerve endings are more susceptible to this 

 compound than the muscular substance. 



An interesting point is the want of correlation between the respiratory and the neuro- 

 muscular effects ; at a time when the latter are most manifest the respiration is 

 practically normal. The explanation is probably to be found in the stimulus of the 

 respiratory centre being physiologically more powerful than the electrical stimulus 

 used, and thus able to overcome any tendency towards paresis of the respiratory 

 muscles. As bearing upon this point, evidence was obtained showing that the paralysis 

 of the muscles and nerve endings was only relative, i.e. only for minimal or moderate 

 stimuli. The effects on the blood-pressure and the neuro-muscular system, on the 

 other hand, are correlative, the fall of blood-pressure being mainly, if not solely, due 

 to an action on the cardiac muscle. 



Remarks on the Action of the Drug on the Respiration. 



Rapid cessation of respiration in the expiratory phase has been described by 

 Tappeiner* after the intravenous injection of methyl-phenyl-isoxazol-methochloride, 

 diphenyl - methyl - pyrazol - methochloride, dimethyl - phenyl - pyrazol - methochloride, 



* Arch. f. exp. Path. u. Pharm., xxxvii., p. 325 [1896]. 



