Effect of catecholamines and adrenergic antagonists on blood glucose, free fatty acids and liver glycogen levels in fed rats.

In fed rats the effects of catechloamines and adrenergic antagonists on blood glucose, free fatty acids (FFA), and liver glycogen levels were investigated in order to determine the role of alpha- and beta-adrenergic receptors in metabolic responses to catechloamines. Hyperglycemic responses to dopamine (DA), noradrenaline (NA), adrenaline (A) and isoprenaline (ISP) were dose-related and accompained by a depletion of liver glycogen. The relative potencies in producing hyperglycemia and in causing liver glycogenolysis were in descending order of potency, A, NA, DA and ISP. Hyperlipemic response was most potent to NA and DA, weaker to ISP, and least potent to A. Phentolamine antagonized completely both hyperglycemia and hepatic glycogen depletion induced by all catecholamines. Propranolol impaired only hyperglycemic responses to A and ISP. Phentolamine antagonized hyperlipemia induced by DA and NA but only partially impaired hyperlipemia after A. Propranolol only partially antagonized hyperlipemic responses to NA and ISP without influencing DA--and A-induced hyperlipemia. The results indicate that in fed rats hyperglycemic responses to catecholamines are mediated mainly by an alpha-adrenergic receptor, and hyperlipemic responses do not fit inton the alpha-receptor or beta-receptor classification.