ADRENALINE (EPINEPHRIN, ADRENINE) 97 



walls, and it is this gradient which according to Straub's theory is 

 necessary for the action of certain alkaloids, which only act during and 

 by virtue of their penetration into the sensitive cells. If the gradient 

 is maintained by a continuous slow flow of adrenaline into the blood 

 stream, the pressure may be kept at a high level for hours at a 

 time, as shown by Kretschmer [1907]. Compare also Straub [1909], 

 When given by the mouth, adrenaline is without pressor action. 

 Applied to a mucous surface, it causes marked local vaso-constriction 

 and blanching ; on this property depends the chief use of adrenaline 

 as a haemostatic in surgery. The repeated intravenous injection may 

 cause serious damage to the arterial walls and bring about arterio- 

 sclerosis. 



B. Action on other Organs containing Involuntary Muscle and on 



Glands. 



Besides affecting the heart and blood vessels, adrenaline acts on 

 plain muscle in many organs of the body. Thus the muscles in the 

 wall of the alimentary canal, excepting the sphincters, become relaxed 

 and their automatic movements cease. The bladder in most animals 

 is relaxed, but in some it contracts. The uterus is also very sensitive 

 to adrenaline ; that of the rabbit and of the pregnant cat contract, but 

 the non-pregnant cat's uterus is relaxed. The amounts of adrenaline 

 which bring about these effects are as minute as those required for 

 the pressor action, or even more minute. Kehrer [1908] obtained 

 tetanic contraction of the pregnant cat's isolated uterus in a bath con- 

 taining adrenaline in a concentration of I in 350,000,000. 



The plain muscle which has perhaps been most commonly em- 

 ployed as a test object for adrenaline is that of the pupil. The 

 mydriatic action of adrenaline after intravenous injection was noted 

 cursorily by Vincent [1897-8] and was first described in detail by 

 Lewandowsky [1898, 1899]. S. J. and C. Meltzer [1904, i] suggested 

 the reaction of the frog's eye as a means for determining the strength 

 of adrenaline solutions, and Ehrmann [1905] subsequently worked 

 out a method, based on this reaction, which enabled him to detect 

 quantities of adrenaline as small as 0*000000002 grm. 



The above apparently divergent actions of adrenaline on plain 

 muscular organs may be viewed from a common standpoint if it is 

 borne in mind that these organs are innervated by branches of the 

 sympathetic system and that the electrical stimulation of sympathetic 

 nerves produces effects similar to those caused by adrenaline (Lew- 

 andowsky, Boruttau, Langley, Elliott). The action of adrenaline (and 



7 



