Metabolic Fate of Glucose in Vascular Smooth Muscle During Contraction Induced by Norepinephrine

• Published in: Journal of molecular and cellular cardiology 1998-03, Vol.30 (3), p.709-719
• Main Authors: Barron, John T, Bárány, Michael, Gu, Liping, Parrillo, Joseph E
• Format: Article
• Language: English
• Subjects: Animals; Biological Transport, Active - drug effects; Carotid Arteries - metabolism; Glucose - metabolism; Glucose oxidation; Glycogen; Glycogen - metabolism; Glycolysis; Glycolysis - drug effects; In Vitro Techniques; Lactic acid; Lactic Acid - metabolism; Muscle contraction; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Norepinephrine; Norepinephrine - pharmacology; Oxidation-Reduction; Oxygen Consumption - drug effects; Swine
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1006/jmcc.1997.0637

The metabolism of glucose in porcine carotid artery was tracked by isotopic methods during sustained isometric contraction induced by 100μmnorepinephrine (NE). In resting muscles, 74 and 18% of glucose taken up was accounted for by glycolysis and glycogen synthesis, respectively. Lactate production accounted for 69%, pyruvate production for 12%, and glucose oxidation accounted for 14% of glycolytic flux. The oxidation of glucose accounted for 57% of the consumption of O2and thus constituted the primary oxidative substrate. During contraction by NE, glucose-uptake declined modestly below the resting basal rate. Glycolysis of external glucose and lactate production decreased and then increased with sustained contraction. Norepinephrine stimulated simultaneous glycogenolysis and glycogen synthesis, with net glycogen synthesis prevailing over 90 min of isometric contraction. Furthermore, NE modified the distribution of glucosyl units throughout the glycogen pool. The steady state rate of oxidation of glucose did not increase during NE contraction, even though O2-consumption increased. In contrast, increased glucose oxidation was demonstrable during contraction induced by 80 mmKCl. Furthermore, oxidation of exogenous fatty acid could be demonstrated during NE-induced contraction. Thus, NE exerts multiple effects on glucose and glycogen metabolism in smooth muscle, but it does not stimulate glucose oxidation.