ABSTRACT
OBJECTIVE:
To investigate the modulation of
nitric oxide synthase (NOS)
isoenzymes in
skeletal muscle during 3 h
ischemia/
reperfusion (I/R, 3 h
ischemia followed by 3 h
reperfusion).
METHODS:
The extensor digitorum longuses (EDLs) from 20
adult rats were divided into 4 groups the normal, the sham operation, the
ischemia (3 h), and the
ischemia/
reperfusion group. One normal EDL from each
rat was used as the non-operated control, and the opposite ones are distributed into the 3 remaining groups. All the samples were studied with
Western blotting technique and
immunohistochemistry staining.
RESULTS:
Three sizes of
protein bands verified with the
proteins of relative molecule to be of 155000, 140000 and 135000, were detected in the EDL homogenate by
Western blotting, which were comparable with the positive controls for nNOS, eNOS and iNOS, respectively. Immunostaining demonstrated that nNOS was present in the
muscle fiber, with a
similar location of the
muscle stria, eNOS was found apparently in microvascular endothelia, but not found in
muscle fibers, and iNOS was found in the
leukocytes around the
muscle fiber and some endothelia
cells. Immunostaining paralleled the
Western blotting results.
CONCLUSIONS:
It suggests that the constitutive nNOS and eNOS
protein can be regulated by I/R, and I/R results in a
down regulation of nNOS and
up-regulation of eNOS and iNOS in reperfused
skeletal muscle. The fact that nNOS is present around stria suggests that nNOS may have a close relationship with
muscle function. The
localization of eNOS in
endothelial cell indicates its
role in regulating
blood supply of the
muscle. Based on these findings, it is possible that NO produced by distinct NOS may
play a different
role in I/R
injury.