EFFECT OF NICOTINE 



181 



reflex inhibition of the heart is also caused, and this leads to a fall in 

 blood pressure. 



If the animal be under curare this reflex inhibition is very clearly 

 seen; for it is then uncomplicated by the results of the convulsive 

 movements. It is abolished by section of the opposite vagus. 



6. Effect of the intravenous injection of a small dose of nicotine. — 

 There are many drugs which when injected directly into the circula- 

 tion produce marked results upon the blood pressure. As a typical 

 instance 05 c.c. of a 01 per cent, solution of nicotine in 1 per cent. 

 NaCl solution is injected into the external jugular vein. To effect 

 this the vein is exposed and a ligature passed round it. About one 



Fig. 143, — Effect of an Injection of Nicotine upon the Blood Pressure. 

 Rabbit. Reduced to One-half Size. 



inch of it is isolated and the lower end is closed by a pair of bull-dog 

 forceps. The vein now distends with blood and the ligature is then 

 tied at the upper end. A single turn only is given to the ligature, so 

 that it can easily be loosened if at a subsequent time we wish to refill 

 the vein with blood. A hypodermic syringe with a fine needle is now 

 filled with the solution to be injected, and the needle inserted into the 

 vein; a procedure which is rendered easy by the distension of the 

 vein. The bull-dog forceps are removed, and at a given signal the 

 injection made. The vein is then emptied of blood and solution by 

 passing the finger along it and the clip forceps replaced in position. 



The result of such an injection is shown in fig. 143. It is seen 

 that a great rise in blood pressure is produced which may be so 



