1 88 INTERNAL SECRETION 



will be seen that stimulation of the isolated sympathetic is followed 

 by a contraction of the capillaries. 



The constricting effect of adrenalin upon the veins seems to 

 be slight, and has, up to the present, received little attention. 



The characteristic effect of adrenalin, namely, the increase in 

 arterial tension, is chiefly the result of an increased peripheral 

 resistance due to the contraction, and consequent reduction in the 

 size of the lumen, of the smaller arteries and the capillaries. 



The enormous power which suprarenal extract has of pro- 

 ducing vaso-contraction, forms the rationale of its therapeutic 

 employment in all those conditions, where the circulation 

 threatens failure in consequence of the sluggishness of the 

 stream. Of these, the most comprehensive are : vascular paralysis, 

 such as may be produced experimentally by destruction or 

 inhibition, by means of toxins (chloral hydrate, chloroform), of 

 the vaso-motor centres, and which is frequently seen in the last 

 stages of some infective diseases and in many toxic states; and 

 cardiac asthenia, in which, owing to inadequacy of the heart 

 muscle and the vascular paralysis, those symptoms of 

 decreased circulation make their appearance which are known 

 as " shock " or " collapse." 



Paralysis of the vessels and cardiac weakness both produce a 

 fall in arterial tension, and lead to a deficiency in the blood 

 supply to the vital nervous centres, as well as to an insufficient 

 filling of the chambers of the heart, cardiac anaemia, and ultimate 

 arrest of the heart's action. By producing contraction of the 

 engorged vessels in the splanchnic area and so raising the blood- 

 pressure, adrenalin effects a more favourable distribution of blood ; 

 it promotes the filling of the chambers of the heart and increases 

 the supply of blood to the nervous system. I found that, even in 

 cases where the nervous system was entirely destroyed, suprarenal 

 extract not only prevented the cessation of the circulation, but 

 that, by its aid, a normal circulation with a respectable arterial 

 tension was maintained for some considerable time. It was upon 

 the basis of these findings that, in 1895 at Professor Albert's 

 Clinic, I injected sterilized suprarenal extract into the veins in 

 two cases of cardiac and vaso-motor paralysis. In one case, the 

 results were negative, but here the autopsy showed that death 

 was due to embolism of the pulmonary artery. The second case 

 was one of extreme collapse with arrested respiration, the result 

 of chloroform narcosis, and here the effect of adrenalin was really 

 startling. The injection was immediately followed by deep, slow 

 respirations which gradually became more frequent, and a full 

 radial pulse was perceptible, which was, however, somewhat slow 

 at first. 



The resuscitating effect of adrenalin has been repeatedly 

 shown in a large number of animal experiments where, owing to 

 haemorrhage, or the arrest of cardiac and respiratory activity in 



