Studies are in progress in order to verify the hypothesis that NO
could possibly be involved in influencingmeat quality during postmortem
aging. In the current study, LT and PM muscles lost NOS activity
after 1 d while SM exhibited NOS activity after 3 d of storage possibly
due to the degradation of nNOS by calpain at different levels. The
proportion of type IIA/X muscle fiber was positively correlated with
the content of nNOS in pork skeletal muscles. Sarcolemma and
cytoplasm localization of nNOS in LT muscle imply a possibility that snitrosylation
would occur and consequently affect the aging of pork
muscles. More researches should be conducted to further prove the
roles of NO and NO induced protein nitrosylation in regulating fresh
meat quality during postmortem aging.