NO介导的宰后成熟期间滩羊肉线粒体通路细胞凋亡对嫩度的影响OA北大核心CSTPCD

The aim of this study was to assess the effect of nitric oxide(NO)-mediated mitochondrial apoptosis on Tan sheep meat tenderness during postmortem aging.The hind leg muscle of Tan sheep was injected with 0.8%NaCl(control),20 mmol/L aminoguanidine hydrochloride(AH)or 90 mmol/L L-arginine(L-Arg)and aged at 4℃for 0,6,12,24,48,96,and 192 h.NO and inducible nitric oxide synthase(iNOS)contents,cytochrome c(Cyt c)redox state,oxidative stress level,mitochondrial apoptotic pathways,and tenderness were measured during postmortem aging.The results indicated that at 12 and 24 h after slaughter,NO and iNOS levels were significantly higher,and ATP levels were significantly lower in the L-Arg group than in the control group(P<0.05).At 24 and 48 h,Cyt c reduction levels and superoxide dismutase(SOD)activity were significantly higher,while the level of reactive oxygen species(ROS)was significantly lower in the AH group than in the control group(P<0.05).From 12 to 96 h,ATP contents were significantly lower in the L-Arg group than in the control group(P<0.05).In addition,at 24 h,Ca2+concentration significantly increased in the L-Arg group compared with the control group(P<0.05).At all time points except 24 h,the caspase-3 activity in the L-Arg group was significantly higher than that in the control group(P<0.05).Moreover,it was found that the Bax/Bcl-2 ratio,pH,and myofibril fragmentation index(MFI)in the L-Arg group were significantly higher than those in the control group at all time points after slaughter(P<0.05).Shear force was significantly lower in the L-Arg group but significantly higher in the AH group than in the control group(P<0.05).In conclusion,NO exacerbates mitochondrial oxidative stress and directly upregulates ROS levels during the postmortem aging of Tan sheep meat,leading to a decrease in SOD activity,irreversible opening of mitochondrial permeability transition pore(MPTP),and ultimately mitochondrial damage.In addition,by controlling the redox state of Cyt c,NO indirectly activates caspase-3 activity to accelerate apoptotic energy metabolism,deplete ATP and consequently maintain myocyte homeostasis.Furthermore,NO affects the release of Ca2+,up-regulates the Bax/Bcl-2 ratio,and induces the occurrence of mitochondrial apoptotic cascade,ultimately resulting in an increase in MFI and a decrease in shear force and,consequently,improving the tenderness of Tan sheep meat.