THE PHARMACOLOGICAL ACTION OF HARMALINE. 



261 



apparent that harmaline causes constriction of the arterioles : a marked constriction in 

 the case of solutions not less dilute than 1 in 5000, and a still perceptible constriction 

 with a solution of 1 in 20,000. I have recently shown * that quinine exerts a similar 

 action on the blood-vessels of the frog. 



(c) Heart and Blood-vessels. [Blood Pressure.) 



In all blood-pressure experiments the animals (rabbits or cats) were first anaesthet- 

 ised with chloroform ; the trachea was then exposed, and a cannula tied into it through 

 which diluted ether was thereafter inhaled. A cannula in the left carotid artery was 

 connected ||with the manometer. Respirations were recorded by means of a double 



Hdi-tnaSM^tj HyThxUUa-r^f 



°-°S. frr. j=f-r R^, 



Fig. 9. 



stethograph attached by a band round the thorax and connected with a Marey's tambour. 

 Iujections were made into the right jugular vein. 



Experiment 31 (fig. 9). — Rabbit, 2200 grammes. 



At 12.35, 0'044 gramme of harmaline hydrochloride dissolved in 2 c.c. Ringer's 

 solution was injected. This was equal to 0'02 gramme per kilogramme. 



This experiment illustrates the effect of a rapidly lethal dose. Blood pressure, 

 after a slight transient rise, rapidly falls. The respirations and heart-beats quickly 

 decrease in rate. The pulsations in the carotid diminish in size in spite of the slowing 

 of the heart. Death is due both to cardiac and respiratory failure. 



Experiment 32 (Table VII., figs. 10 to 14 inclusive). — Rabbit, 2000 grammes. 



Successive actual doses of 0"002 grm., 0'004 grm., 0*008 grm., and 0'016 grm., each 

 dose being dissolved in 2 c.c. of Ringer's solution. This experiment shows the effects 

 of increasing sub-lethal doses on the blood pressure and the respirations of the 

 rabbit. 



* Archives internal, de Pharmacodynamie, 1909, p. 319. 

 TRANS. ROY. SOC. EDIN., VOL. XLVII. PART II. (NO. 11). 39 



