Glycogen metabolism during tension generation and maintenance in vascular smooth muscle

R. M. Lynch, C. P. Kuettner, R. J. Paul

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

To study the regulation of glycogen utilization in vascular smooth muscle, we measured the content of glycogen and glucose 6-phosphate and the activity of the glycogen phosphorylase and glycogen debrancher enzymes in porcine carotid artery. During active contraction, the rates of glycogen phosphorylase and glycogenolysis were as high as expected. Despite this, glycogen content did not decrease to less than ~50% of control levels even after sustained contractions. The activity of glycogen debrancher enzyme was found to be limiting glycogen utilization at this point. Although glycogenolysis is closely coordinated with increases in oxidative metabolism concomitant with active contraction, the maximal level of tension obtained after stimulation was not substantially reduced under conditions where glycogen debrancher enzyme was limiting glycogen utilization. On the other hand, the rate of tension generation was increased in these tissues. Thus glycogen utilization is not necessary for maximal force generation per se, but may influence other muscle contractile properties. Finally, during steady-state tension maintenance, glycogen utilization is likely to be regulated by the intracellular concentrations of metabolic intermediates (glucose, glucose 6-phosphate), as it is in skeletal muscle.

Original languageEnglish (US)
Pages (from-to)26/4
JournalAmerican Journal of Physiology - Cell Physiology
Volume257
Issue number4
StatePublished - Jan 1 1989
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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