Targeted disruption of the nitric oxide synthase 2 gene protects against ischaemia/reperfusion injury to skeletal muscle.
To provide definitive insight into the complicated roles of the nitric oxide synthase (NOS) enzymes in ischaemia/reperfusion (I/R) injury of skeletal muscle, experiments were undertaken in mice with targeted disruption of the inducible NOS (NOS-2 KO) isoform, compared with the wild-type mouse strain. The degree of I/R injury in the NOS-2 KO mice was attenuated relative to that in the wild-type strain. After 70 min of ischaemia (24 h reperfusion), nitroblue tetrazolium (NBT) staining of skeletal muscle showed significant necrosis (40%) in wild-type mice, whilst in NOS-2 KO mice, ischaemia could be prolonged to 90 min before significant necrosis (38%) was apparent. Specific enzyme activities of the mitochondrial respiratory chain enzymes, measured in skeletal muscle homogenates, suggested that direct inhibition of the enzymes is not causal in the I/R injury. Immunohistological examination of skeletal muscle for NOS-2 showed its induction selectively in mast cells. In vitro experiments using bone marrow-derived mast cells showed that NOS-2 induction was associated with increased degranulation of mast cells. These findings suggest that NO generated by induction of NOS-2 has a deleterious effect in I/R injury of skeletal muscle and that NO exerts its damaging effect through factors released by degranulation of mast cells.
Barker
J E
JE
Leukocyte Biology Section, Division of Basic Medical Sciences, Imperial College School of Medicine, South Kensington, London SW7 2AZ, UK.
Knight
K R
KR
Romeo
R
R
Hurley
J V
JV
Morrison
W A
WA
Stewart
A G
AG
D000818:Animals; D001834:Body Water / Q000378:metabolism; D018929:Cell Culture Techniques; D015550:Cell Degranulation / Q000502:physiology; D008407:Mast Cells / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008931:Mitochondria, Muscle / Q000201:enzymology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000201:enzymology / Q000473:pathology; D009336:Necrosis; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D009580:Nitroblue Tetrazolium; D015427:Reperfusion Injury / Q000201:enzymology* / Q000473:pathology; D013997:Time Factors
D009580:Nitroblue Tetrazolium; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse