Chapter XII 



THE RELATION OF THE ADRENALS TO CARBO- 

 HYDRATE METABOLISM 



Considerable confusion exists in the earlier literature con- 

 cerning the role of the adrenals in carbohydrate metabolism. 

 Following Blum's 64 demonstration that epinephrine injections 

 elicit glycosuria, numerous workers attributed importance to 

 epinephrine secretion as a regulator of glucose metabolism. 

 Aside from numerous technical sources of error and misinter- 

 pretation of observed findings, confusion resulted from a failure 

 to dissociate the hypoglycemic effects of adrenal cortical in- 

 sufficiency from the hyperglycemic effects of epinephrine. 



In the normal organism the glucose content of the blood is 

 maintained at a relatively constant level. The utilization of 

 glucose by the muscles and tissues is accompanied by glyco- 

 genosis (the breakdown of glycogen) in the liver and muscles 

 which process furnishes a supply of glucose to replace that 

 consumed in metabolic processes. The mechanism of this 

 carbohydrate control involves a number of physiological reac- 

 tions. Stimulation of the splanchnic nerves or the injection 

 of epinephrine, as we have seen (Chapter VII), cause a libera- 

 tion of glucose from the liver. Stimulation of the brain stem 

 in the region of the pons (the piqure of Claude Bernard) causes 

 a reflex stimulation of glycogenolysis which is mediated through 

 the splanchnic nerves but fails to occur (if these nerves are cut 

 or the adrenals are removed) only when the glycogen store of 

 the liver is reduced. If large stores of glycogen are present in 

 the liver, adrenalectomy or severance of the splanchnics does 

 not prevent the appearance of hyperglycemia. Moreover, 

 atropine, which paralyzes the parasympathetic nerves, pre- 

 vents the development of hyperglycemia following pontine 



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