Metabolic responses to catecholamines.

Area of Science:

• Pharmacology
• Endocrinology
• Physiology

Background:

• Beta-adrenergic agonists like isoproterenol and adrenaline are known to affect glucose and potassium metabolism.
• The precise roles of different adrenergic receptors and tissues in these responses remain incompletely understood.

Purpose of the Study:

• To investigate the effects of isoproterenol, propranolol, adrenaline, and sotalol on serum glucose and potassium levels in conscious rats and anesthetized dogs.
• To explore the involvement of skeletal muscle in mediating the rapid changes in serum potassium induced by adrenaline.

Main Methods:

• Administration of various adrenergic agents (isoproterenol, propranolol, adrenaline, sotalol) and a beta-adrenergic blocker to conscious rats and anesthetized dogs.
• Measurement of serum glucose and potassium concentrations at different time points post-administration.
• Intra-arterial administration of adrenaline into the isolated hind limb of the dog to assess localized effects.

Main Results:

• Isoproterenol and propranolol induced hyperglycemia in both species.
• Adrenaline caused hyperglycemia and transient hyperkalemia followed by hypokalemia in dogs.
• Sotalol blocked adrenaline-induced hyperglycemia and late hypokalemia but not early hyperkalemia.
• In isolated canine hind limb, adrenaline increased glucose but decreased venous potassium compared to arterial potassium.

Conclusions:

• Different adrenergic receptors likely mediate the glucose and potassium responses to adrenaline.
• Skeletal muscle plays a significant role in regulating the early hyperkalemic response to adrenaline.