Reduced hexokinase II impairs muscle function 2 wk after ischemia-reperfusion through increased cell necrosis and fibrosis

J Appl Physiol (1985). 2012 Aug 15;113(4):608-18. doi: 10.1152/japplphysiol.01494.2011. Epub 2012 Jun 21.

Abstract

We previously demonstrated that hexokinase (HK) II plays a key role in the pathophysiology of ischemia-reperfusion (I/R) injury of the heart (Smeele et al. Circ Res 108: 1165-1169, 2011; Wu et al. Circ Res 108: 60-69, 2011). However, it is unknown whether HKII also plays a key role in I/R injury and healing thereafter in skeletal muscle, and if so, through which mechanisms. We used male wild-type (WT) and heterozygous HKII knockout mice (HKII(+/-)) and performed in vivo unilateral skeletal muscle I/R, executed by 90 min hindlimb occlusion using orthodontic rubber bands followed by 1 h, 1 day, or 14 days reperfusion. The contralateral (CON) limb was used as internal control. No difference was observed in muscle glycogen turnover between genotypes at 1 h reperfusion. At 1 day reperfusion, the model resulted in 36% initial cell necrosis in WT gastrocnemius medialis (GM) muscle that was doubled (76% cell necrosis) in the HKII(+/-) mice. I/R-induced apoptosis (29%) was similar between genotypes. HKII reduction eliminated I/R-induced mitochondrial Bax translocation and oxidative stress at 1 day reperfusion. At 14 days recovery, the tetanic force deficit of the reperfused GM (relative to control GM) was 35% for WT, which was doubled (70%) in HKII(+/-) mice, mirroring the initial damage observed for these muscles. I/R increased muscle fatigue resistance equally in GM of both genotypes. The number of regenerating fibers in WT muscle (17%) was also approximately doubled in HKII(+/-) I/R muscle (44%), thus again mirroring the increased cell death in HKII(+/-) mice at day 1 and suggesting that HKII does not significantly affect muscle regeneration capacity. Reduced HKII was also associated with doubling of I/R-induced fibrosis. In conclusion, reduced muscle HKII protein content results in impaired muscle functionality during recovery from I/R. The impaired recovery seems to be mainly a result of a greater susceptibility of HKII(+/-) mice to the initial I/R-induced necrosis (not apoptosis), and not a HKII-related deficiency in muscle regeneration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Disease Models, Animal
  • Down-Regulation
  • Fibrosis
  • Glycogen / metabolism
  • Hexokinase / deficiency*
  • Hexokinase / genetics
  • Hindlimb
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microcirculation
  • Mitochondria, Muscle / metabolism
  • Mitochondria, Muscle / pathology
  • Muscle Fatigue
  • Muscle Strength*
  • Muscle, Skeletal / blood supply*
  • Muscle, Skeletal / enzymology*
  • Muscle, Skeletal / pathology
  • Muscle, Skeletal / physiopathology
  • Necrosis
  • Neovascularization, Physiologic
  • Oxidative Stress
  • Recovery of Function
  • Regeneration
  • Regional Blood Flow
  • Reperfusion Injury / enzymology*
  • Reperfusion Injury / genetics
  • Reperfusion Injury / pathology
  • Reperfusion Injury / physiopathology
  • Time Factors
  • bcl-2-Associated X Protein / metabolism

Substances

  • Bax protein, mouse
  • bcl-2-Associated X Protein
  • Glycogen
  • Hexokinase