ABSTRACT
The study's purpose was to investigate if physical activity initiated with the start of high-fat feeding would oppose development of endothelial dysfunction, and if it does, then to determine some potential mechanisms. C57BL/6 female mice were randomly divided into three groups: (1) control low-fat diet (LF-SED; 15% of calories from fat), (2) high-fat diet (HF-SED; 45% of calories from fat), and (3) HF diet given access to a voluntary running wheel (HF-RUN). Our hypothesis was that HF-RUN would differ in multiple markers of endothelial dysfunction from HF-SED after 10 weeks of 45%-fat diet, but would not differ from LF-SED. HF-RUN differed from HF-SED in nine determinations in which HF-SED either had decreases in (1) acetylcholine (ACh)-induced and flow-induced vasodilatations in isolated, pressurized coronary arterioles, (2) heart phosphorylated endothelial nitric oxide synthase (p-eNOS/eNOS) protein, (3) coronary arteriole leptin (ob) receptor protein, (4) phosphorylated signal transducer and activator of transcription 3 (p-STAT3/STAT3) protein, and (5) coronary arteriole superoxide dismutase 1 protein; or had increases in (6) percentage body fat, (7) serum leptin, (8) coronary arteriole suppressor of cytokine signalling 3 (SOCS3) protein, and (9) coronary arteriole gp91(phox) protein. Higher endothelium-dependent vasodilatation by ACh or leptin was abolished with incubation of NOS inhibitor N(G)-nitro-l-arginine-methyl ester (l-NAME) in LF-SED and HF-RUN groups. Further, impaired ACh-induced vasodilatation in HF-SED was normalized by apocynin or TEMPOL to LF-SED and HF-RUN. These findings demonstrate multiple mechanisms (eNOS, leptin and redox balance) by which voluntary running opposes the development of impaired coronary arteriolar vasodilatation during simultaneous high-fat feeding.