ACONITE . 461 



of the cardiac muscle and paralysis of the peripheral vagus 

 endings occurring simultaneously. 



The vasomotor system is not influenced by medicinal 

 doses, but the blood pressure is lowered through the slowing 

 of the heart beats, prolonged diastole, and lessened systolic 

 contractions. In poisoning there is paralysis of the vaso- 

 motor centres. 



The heart is arrested in diastole, but death immediately 

 results from respiratory failure. 



Nervous System. — The most striking effect of aconite 

 on the nervous system (in man) consists in tingling followed 

 by loss of sensation and temperature sense after large medi- 

 cinal doses. This phenomenon is due to stimulation succeeded 

 by depression of the sensory nerve terminations. The drug 

 is not comparable with opium, since doses large enough to 

 produce a general anodyne action are dangerous. 



Poisonous doses of aconite cause muscular twitching 

 and loss of motor power, which result from excitation, and 

 finally paralysis of the motor nerve endings. Convulsions 

 occur in poisoning. These are thought to follow stimulation 

 of the medulla as the higher cerebral centres are often un- 

 impaired. Stimulation and then depression of the lower 

 divisions of the nervous system — especially the medulla and 

 peripheral sensory and motor nerves — describe the general 

 effect of aconite. Its influence over the cord is uncertain. 



Respiraiion.—ThQ breathing of animals under the in- 

 fluence of aconite resembles that observed after section of 

 the vagi. The respiration is slow and labored ; the expira- 

 tion is prolonged, and is succeeded by a considerable interval 

 before the next inspiration. This condition is brought about 

 by depression of the medullary respiratory centres. 



Temperature. — The bodily heat is reduced by aconite 

 in fever, after medicinal doses, and in poisoning by the drug. 

 Vascular dilatation, retarded circulation, and therefore heat 

 dissipation, probably explain the antipyretic action. 



Skin. — Aconite sometimes produces slight diaphoresis. 

 The cause of this action is unknown. 



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