62 The Endocrine Organs 



arterial pressure (J. D. Cameron). Moore and Purinton found that with very minute 

 doses a fall of pressure may be obtained instead of a rise. If the amount injected is 

 considerable, the rise of blood-pressure caused by vascular contraction and heart 

 acceleration may be enormous three or four times the normal and the amount of 

 strain put on the heart is correspondingly great. Sometimes the heart muscle is 

 \inable to respond properly xinder these circumstances and the ventricular action 

 becomes fibrillar delirium cordis being produced, generally leading to instant 

 death. This seems especially liable to occur in a particular phase of early chloro- 

 form anaesthesia (Levy). 



As a general rule a number of successive injections can be made into a vein, and 

 each one will produce an amount of rise of blood-pressure proportionate to the 

 amount of autacoid in the extract : the activity can in fact be gauged by this 

 method. Other modes of testing the activity of suprarenal extracts are (1) by 



FIG. 39. Etl'ect of solution of adrenalin upon an isolated portion of uterus of rat. 



The contractions are inhibited. 



their action when added to Ringer's solution perfused through the blood-vessels of 

 a frog the central nervous system of which has been destroyed, (2) by the effect 

 produced upon the pupil of the excised eye of a frog when immersed in Ringer's 

 solution to which a definite amount of the extract is added, (3) by immersion of the 

 excised uterus of a rat in a similar solution kept aerated by a stream of oxygen and 

 maintained at body temperature, (4) the same, using a piece of intestine instead 

 of uterus, and (5) the same, using strips of artery cut transversely. 



The effect of suprarenal extract upon the heart and vessels is not the 

 only action upon plain muscle, although it is the most obvious. Other- 

 involuntary muscular tissue supplied by sympathetic fibres is also affected. 

 This may be in the direction of increased contraction (sphincters of pylorus 

 and of ileocsecal valve, spleen, vagina, uterus, 1 vas deferens, retractor penis), 



1 Cushny finds that the uterus of a pregnant cat is contracted by adrenalin, whilst the 

 non-pregnant uterus is usually inhibited. In the rat inhibition is the usual effect (fig. 39), 

 but in the rabbit (fig. 40) and most animals contraction is produced. 



