Reduced hexokinase II impairs muscle function 2 wk after ischemia-reperfusion through increased cell necrosis and fibrosis.
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.
Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, Academic Medical Center, Amsterdam, The Netherlands.
Kirsten M
KM
Smeele
Otto
O
Eerbeek
Gert
G
Schaart
Anneke
A
Koeman
Rick
R
Bezemer
Jessica K
JK
Nelson
Can
C
Ince
Rianne
R
Nederlof
Maxim
M
Boek
Markku
M
Laakso
Arnold
A
de Haan
Maarten R
MR
Drost
Markus W
MW
Hollmann
Coert J
CJ
Zuurbier
D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D015536:Down-Regulation; D005355:Fibrosis; D006003:Glycogen / Q000378:metabolism; D006593:Hexokinase / Q000172:deficiency* / Q000235:genetics; D006614:Hindlimb; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008833:Microcirculation; D008931:Mitochondria, Muscle / Q000378:metabolism / Q000473:pathology; D018763:Muscle Fatigue; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D009336:Necrosis; D018919:Neovascularization, Physiologic; D018384:Oxidative Stress; D020127:Recovery of Function; D012038:Regeneration; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494827:Bax protein, mouse; D051028:bcl-2-Associated X Protein; D006003:Glycogen; D006593:Hexokinase