RELATION SUPRARENAL GLANDS TO CIRCULATION 227 



conclusion that epinephrin ordinarily has no effect upon the pulmonary 

 circulation. 



Schafer and Lim (1919) have ^investigated the problem, using cats, 

 dogs and rabbits as experimental animals. Epinephrin was administered 

 sometimes by jugular vein, sometimes by carotid artery. Elaborate pre- 

 cautions were taken to rule out the effects of adventitious factors. Both 

 pulmonary and systemic blood-pressure was recorded. They found that 

 in the rabbit epinephrin injected in moderate doses into the jugular vein 

 caused at first either a rise of pulmonary blood-pressure due to constriction 

 of the pulmonary arterioles, or no effect. But when the drug reached the 

 systemic arterioles the rise in systemic pressure that ensued was accom- 

 panied by a fall in the pulmonary pressure, with gradual return to normal 

 as the constriction in the systemic vessels disappeared. Similar results 

 were sometimes seen in the cat, but the usual result was a well-marked 

 rise in pressure in both the pulmonary and systemic arteries. With unusu- 

 ally small doses a fall of pressure was seen in each system. In the dog, 

 intravenous injections of fairly large doses resulted in a great rise of 

 pressure in both systems, sometimes running almost parallel, sometimes 

 better marked in the pulmonary than in the systemic arteries. In all three 

 animals, when the injections were made by vein, the pulmonary rise was 

 sometimes very distinctly in advance of the systemic, and when injection 

 was made into an artery the systemic rise appeared first. In many -ani- 

 mals, however, the rise was simultaneous in each system. The rise in 

 pulmonary pressure could not be ascribed to back pressure from the aoTta 

 because, in some instances, marked increase in the aortic system was noted 

 with no rise whatever in the pulmonary pressure and because of the tem- 

 poral relations of the reactions. The chief effects in the rabbit were 

 ascribed to the constricting influence of the drug upon the blood vessels 

 of both systems, but in most cats and in dogs the effect appeared to be 

 due chiefly to action on the cardiac musculature. 



The sum total of the available evidence would seem to indicate that 

 the effects of epinephrin in the lungs are not such as to influence markedly 

 the general circulation. With large doses, some degree of pulmonary con- 

 striction occurs, but this would seem to be sufficiently compensated for by 

 the concomitant stimulation of the heart. With smaller and supposedly 

 more nearly physiologic quantities, some degree of dilatation, and hence 

 perhaps of freer blood flow in the pulmonary vessels, results. The data 

 as a whole afford no substantial basis for teleological speculation. 



When very large doses of epinephrin are administered by vein to an 

 intact animal the pulmonary circulation is sometimes overwhelmed, with 

 resulting acute edema of the lungs. Seldom is an investigator confronted 

 with so striking a picture as that presented by this condition. Its onset 

 is almost instantaneous. Blood-stained froth begins to flow from the 

 respiratory orifices in a voluminous stream. Respiration at first is labored 



