ACONITINE. 
§ 438.] 
373 
become irregular as in the action of the digitalis group. There is finally 
arrest in diastole—at first removed by atropine, but in the next stage 
atropine has no effect, for there is complete paralysis of the brake nervous 
centre as well as the vaso-motor centre ; if, however, the vagus is stimu¬ 
lated the beats may recommence, to be followed by final complete arrest. 
This sequence is not always easy to follow, because the least overdose 
obscures the successive stages by almost at once paralysing the nervous 
centres. Durdufi 1 has shown that, contrary to the poisons of the 
digitalis group, the extensibility of the heart is diminished, that is to 
say, its volume is lessened. 
The mammalian heart is similarly affected to that of the frog. 
With small doses of aconitine, the relation of pulse frequency and 
blood-pressure varies somewhat according to the particular aconitine, as 
it affects the central origin of the nerves of the vessels and the vagus. 
Thus sometimes the pulse slows without sinking of the blood-pressure, 
and sometimes there is increase of pulse and rise of blood-pressure. 
Matthews has registered by means of a myocardiagraph the movements 
of the exposed heart of a dog after aconitine had been introduced into 
the circulation, and seen arhythmic beats and fibrillar contractions of 
the ventricle, results of exalted sensibility and excitability of the heart 
muscle. All researches show that aconitine is extremely poisonous to 
the mammalian heart; so minute a quantity as 1 part of aconitine to 
5 million of the blood notably quickens the pulse even up to 109-131, 
the pulse at once sinking to normal if unpoisoned blood is allowed to 
replace the blood containing aconitine. Doses of 1 of aconitine to 1J 
million of blood are fatal within seven minutes by arrest of the heart beat. 
In fatal cases the enormous rise of frequency of heart beat is followed by 
sudden arrest of the left ventricle, whilst the right auricle and ventricle 
may continue to beat for a quarter to half an hour. In this condition 
the beat of the left ventricle cannot be restored by normal blood or by 
any stimulating means whatever. 
The effects of indaconitine 2 are strikingly similar to those of aconi¬ 
tine ; the phases of slowing of the pulse and marked quickening and 
subsequent arhythmia due to inco-ordinate action of auricles and ven¬ 
tricles are all present. *06 mgrm. administered to etherised cats sub¬ 
cutaneously every forty-five minutes was fatal seventy minutes after the 
third dose. 
1st injection. Temporary acceleration, then slowing, of the pulse 
and respiration ; moderate fall of arterial pressure. 
2nd injection. Similar effects, but no acceleration of pulse or 
respiration. 
1 Archiv f. exper. Path., Bd. xxv. 
2 “ The Pharmacology of Indaconitine,” by J. Theod. Cash, M.D., and Wyndham 
R. Dunstan, M.D., Proc. Roy. Soc., vol. lxxvi. 
