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Effect of aging and exercise training on eNOS uncoupling and O2‐ signaling in skeletal muscle arterioles
Author(s) -
Sindler Amy Lynn,
Delp Michael D,
Reyes Rafael A,
Wu Guoyao,
MullerDelp Judy M
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.608.12
Subject(s) - chemistry , nitric oxide , medicine , endocrinology , soleus muscle , sed , catalase , skeletal muscle , enos , microcirculation , vasodilation , arteriole , hydrogen peroxide , nitric oxide synthase , biochemistry , oxidative stress
Reduced availability of tetrahydrobiopterin (BH 4 ) contributes to the age‐related decline of nitric oxide (NO)‐mediated dilation in soleus muscle arterioles. Depending on the availability of substrate and/or necessary co‐factors, eNOS can generate NO and/or superoxide (O 2 − ). We evaluated the effects of age and exercise on flow‐induced dilation (FID) and flow‐induced production (FIP) of NO and O 2 − in soleus muscle arterioles. Young (4 mo) and old (22 mo) male rats were exercise trained (ET) or remained sedentary (SED) for 10 wks. FID was studied in soleus muscle arterioles under control conditions and during the blockade of O 2 − and/or hydrogen peroxide. FIP of NO and O 2 − were determined. Arteriolar BH 4 levels were also determined. ET enhanced FID in Y and O rats. ET restored BH 4 and improved FIP of NO in arterioles O rats. FIP of O 2 − was higher in OSED vs. YSED. ET increased FIP of O 2 − in arterioles from Y rats. O 2 − scavenging with Tempol reduced FID in all rats except YSED. Addition of catalase to Tempol‐treated arterioles eliminated FID in all groups. Catalase alone reduced FID in all groups except OSED, with the greatest effect in YSED. FID was restored when deferoxamine, an iron chelator, was added to Tempol‐treated arterioles. These data indicate that uncoupling of eNOS contributes to the age‐related decline in FID; however, reactive oxygen species are required for FID in soleus muscle arterioles from Y and O rats.