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Eur J Appl Physiol. 2013 Nov;113(11):2761-8. doi: 10.1007/s00421-013-2715-7. Epub 2013 Aug 31.

Effect of age and exercise training on protein:protein interactions among eNOS and its regulatory proteins in rat aortas.

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  • 1Department of Health and Kinesiology, Texas A&M University, MS 4243, College Station, TX, 77843-4243, USA.



We tested the hypothesis that impaired endothelium-dependent relaxation in aged aorta is due, in part, to altered protein:protein interactions between endothelial nitric oxide synthase (eNOS) and key regulatory proteins resulting in impaired nitric oxide (NO)-mediated relaxation. We also hypothesized that endurance exercise training improves or restores NO-mediated vasorelaxation in aged aorta by reversing the detrimental effects of aging on protein:protein interaction between eNOS and its key regulatory proteins.


Young (2 month) and old (22 month) rats were exercise trained (Ex) or remained sedentary (Sed) for 10 weeks yielding four groups of rats: (1) young Sed, (2) young Ex, (3) old Sed, and (4) old Ex. Endothelium-dependent relaxation to acetylcholine (ACh) and protein:protein interactions were assessed in aortas. To determine the role of eNOS, endothelium-dependent relaxation to ACh was assessed in the presence of L-NAME. Protein:protein interactions were assessed using co-immunoprecipitation.


Acetylcholine-induced relaxation was impaired in OldSed relative to YoungSed aortas. Training restored ACh-induced vasorelaxation responses so that OldEx were not different from YoungSed. L-NAME abolished the effects of age and exercise training on ACh-induced relaxation responses. Aging resulted in lower Cav1:eNOS and CaM:eNOS interactions but had no effect on Hsp90:eNOS interaction. Exercise training did not alter protein:protein interactions.


Nitric oxide-mediated, endothelium-dependent relaxation is impaired in old aorta, which is associated with reduced Cav1:eNOS and CaM:eNOS interactions. Exercise training restores endothelium-dependent relaxation in old aortas by enhancing NO-mediated vasorelaxation. The beneficial effect of training is not mediated by reversing the detrimental effects of aging on protein:protein interactions between eNOS and its key regulatory proteins.

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