315 



HO 



Phenylalanine has been shown to be a precursor of adrenaline and 

 noradrenaline. Synthesis involves oxidation of the aromatic ring and 

 side chain and decarboxylation. The conversion of noradrenaline to 

 adrenaline by a methylation reaction involving ATP has also been 

 suggested. 



When adrenaline is injected it causes constriction of the arterioles, 

 increases blood pressure, and stimulates the heart. In anger or fear the 

 amount of adrenaline automatically increases, followed by a marked 

 increase in blood sugar and lactic acid. The natural l form is 15 

 times more effective than the d form. A solution consisting of 1 part 

 of adrenaline hydrochloride to 300,000,000 parts of water causes a 

 physiological response in animals. 



Noradrenaline and adrenaline are jnesumed to function in the 

 transmission of ner\'e impulses in the sympathetic nervous system 

 (page 309). However, alternate systems must be available, as the 

 medulla can be removed without harm. 



ADRENAL CORTEX. Although the medulla does not appear to be es- 

 sential for life, animals perish if the adrenal glands are removed be- 

 cause the cortex plays an important physiological role. Loss of the 

 cortex by surgical removal or by disease results in loss of sodium, in- 

 creased blood potassium, decreased glycogen in liver and muscle after 

 fasting, decreased glucose in serum, and inability to excrete ingested 

 water. Emaciation, low blood pressure, and abnormal pigmentation of 

 the skin result. These findings are similar to those observed in Addi- 

 son's disease in man. Hormones in cortical extracts prevent and cure 

 this disease. 



About 30 steroids have been isolated from the adrenal cortex. The 

 chemical configurations of these have been determined, and several 

 of them have been synthesized. The hormones may be grouped into 

 two classes from the functional standpoint: (1) those with predomi- 

 nant action on electrolyte and water regulation, and (2) the corticoids, 

 which exert their influence on carbohydrate metabolism. Deoxycorti- 



