More tetanic contractions are required for activating glucose transport maximally in trained muscle

Kentaro Kawanaka, Izumi Tabata, Mitsuru Higuchi

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Exercise training increases contraction-stimulated maximal glucose transport and muscle glycogen level in skeletal muscle. However, there is a possibility that more muscle contractions are required to maximally activate glucose transport in trained than in untrained muscle, because increased glycogen level after training may inhibit glucose transport. Therefore, the purpose of this study was to investigate the relationship between the increase in glucose transport and the number of tetanic contractions in trained and untrained muscle. Male rats swam 2 h/day for 15 days. In untrained epitrochlearis muscle, resting glycogen was 26.6 μmol glucose/g muscle. Ten, 10-s-long tetani at a rate of 1 contraction/min decreased glycogen level to 15.4 μmol glucose/g muscle and maximally increased 2- deoxy-D-glucose (2-DG) transport. Training increased contraction-stimulated maximal 2-DG transport (+71%; P < 0.01), GLUT-4 protein content (+78%; P < 0.01), and resting glycogen level (to 39.3 μmol glucose/g muscle; P < 0.01) on the next day after the training ended, although this training effect might be due, at least in part, to last bout of exercise. In trained muscle, 20 tetani were necessary to maximally activate glucose transport. Twenty tetani decreased muscle glycogen to a lower level than 10 tetani (18.9 vs. 24.0 μmol glucose/g muscle; P < 0.01). Contraction-stimulated 2-DG transport was negatively correlated with postcontraction muscle glycogen level in trained (r = -0.60; P < 0.01) and untrained muscle (r = -0.57; P < 0.01).

Original languageEnglish
Pages (from-to)429-433
Number of pages5
JournalJournal of Applied Physiology
Volume83
Issue number2
Publication statusPublished - 1997 Aug
Externally publishedYes

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Keywords

  • 2-deoxy-D-glucose transport
  • Epitrochlearis
  • Muscle glycogen

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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