THE PHARMACOLOGICAL ACTION OF HARM ALINE. 



265 



as a study of the uncomplicated action of harmaline on the blood pressure and 

 respiration. 



Experiment 33. — (Table VIII., fig. 15). — Cat, 3000 grammes. This experiment 

 illustrates certain differences between the blood-pressure effects in the cat and those in 

 the rabbit ; it also shows the terminal phenomena in a case where respiratory failure 

 definitely precedes arrest of the heart (contrast fig. 9). 



At first, three injections were given, each of 0001 grm. per kilo. The first and third 

 injections caused a slight rise of blood pressure, the second a fall. The effects of small 



Table VIII. — Experiment 33. 



Time. 



Dose 



of 



Harmaline. 



Average 



Pulse 



Rate of 



Respiration 



Notes. 



B.P. in mm. 



Rate. 



Respirations. 



Excursus. 



5.3 





164 



27 



9 



5 mm. 





5.3.40" 



0'001 grm. per kilo 













5.4 





175 



24 



9 



5 mm. 





5.5 





166 



24 



7 



4 „ 





5.6 





166 



25 



8 



4 „ 





5.7.30" 





170 



24 



8 



4 „ 





5.8 



001 grm. per kilo 













5.8.10" 





154 



22 



8 



4 mm. 





5.10 





158 



24 



8 







5.10.50" 



0"001 grm. per kilo 









4 mm. 





5.11 





162 



25 



9 



4 „ 





5.12 





158 



22 



8 



4J „ 





5.21 





150 



24 



8 



4 „ 





5.21.30" 



004 grm. per kilo 













5.21.50" 





138 



20 



7 



4 mm. 





5.23 





146 



20 



6 



4 ., 





5.29 





140 



24 



6 



4 „ 





5.37 





116 



30 



7 



4 „ 





5.40 





122 



27 



6 



4 „ 





5.40.30" 



01 grm. per kilo 











Fig. 15. 



5.50.30" 





96 



20 



9 



2 mm. 





5.51 





64 



19 



4 



2 „ 





5.52 





50 



18 



1 



1 „ 





5.53 





36 



16 







o „ 





5.57 

















o „ 





doses are therefore inconstant, and it was found in other experiments that, in the cat in 

 contrast to the rabbit, small doses of harmaline produce either a very slight rise, or 

 sometimes no rise, of blood pressure. 



When this experiment is compared with Experiment 32, it is also seen that in the 

 cat, after a total dose of 0'007 grm. per kilo, there is a considerable and permanent fall 

 of blood pressure, whereas in the rabbit after the same dose blood pressure, after a 

 temporary fall, recovers to the normal level. These differences are probably due to the 

 fact that changes in blood pressure which are due to an action on the arterioles are more 

 marked in the rabbit than in the cat, owing to the much greater length of the intestinal 



