Effects of Epinephrine Injections upon Deep and Superficial Blood Vessels of Frog's Tongue.

Investigations by Cannon and his collaborators 1 , 2 , 3 , 4 have shown that while intravenous injections of epinephrine cause the whole limb to decrease in volume, an increase in volume may be recorded if the skin of the limb has been removed. In other words, epinephrine causes vasoconstriction in the vessels of the skin but not in those of the muscle. We have observed a similar phenomenon in the arterioles of the frog's tongue. If the frog's tongue is observed under the microscope, the superficial capillaries supplying the mucous membrane can be seen as loops closely resembling the familiar capillary loops in the human skin, while the deeper vessels supplying the muscles of the tongue run a much less tortuous course. After the injection of 1.5 cc. of 1:100,000 epinephrine solution into the dorsal or ventral lymph sac, most of the superficial capillaries become perfectly bloodless, while in others, the flow of blood corpuscles is greatly retarded. No such contraction or retardation can be noted, however, in the deeper capillaries and arterioles supplying the muscles of the tongue.

These observations show that the same contrast between the effects of epinephrine on the superficial vessels and in the deeper vessels takes place in the frog as has been observed in mammals.