Author:
Garceau Denis,Yamaguchi Nobuharu,Goyer Robert,Guitard Francine
Abstract
The metabolic role of neurally released noradrenaline (NA) was studied in the liver of anesthetized dogs. Sustained stimulation with various frequencies was directly applied on the anterior plexus of hepatic nerves. Stimulation-induced changes in plasma concentrations of endogenous catecholamines in hepatic venous blood were determined in correlation with concomitant changes in those of glucose (GL). Mean basal values for hepatic venous NA, adrenaline, dopamine, and GL were 0.062, 0.022, 0.032 ng/mL, and 97.9 mg%, respectively. Among these catecholamines, NA was the only one being released significantly during stimulation. While hepatic venous NA increased rapidly during stimulation, being maximum within 3 min, hepatic venous GL increased gradually, reaching a maximum value 5 min after the onset of stimulation. A highly significant correlation (r = 0.90, P < 0.001) was found between changes in hepatic venous NA and GL concentrations observed during stimulation at various frequencies (2–16 Hz). However, hepatic vasoconstricting responses to stimulation were not correlated with increased hepatic venous GL. An α-blockade with phentolamine (2 mg/kg, iv) resulted in diminished release of GL by approximately 50% (P < 0.05) and reduced hepatic arterial vasoconstriction by approximately 47% (P < 0.01) upon stimulation (8 Hz, 5 min), even though NA release was markedly enhanced. We conclude that in the dog, NA is the sole catecholamine released within the liver in response to direct hepatic nerve stimulation, and NA thus released mediates the hepatic glycogenolysis via α-adrenoceptors.
Publisher
Canadian Science Publishing
Subject
Physiology (medical),Pharmacology,General Medicine,Physiology
Cited by
24 articles.
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