Abstract 5074: Exercise Training Improves Muscle Vasodilatation Response in Individuals with T786C Polymorphism of Endothelial Nitric Oxide Synthase Gene
Introduction: The T allele at position 786 of the promoter region in the eNOS gene has been associated with an increase in the incidence of cardiovascular events and coronary spasm, which suggests that this allele increases the susceptibility for endothelial dysfunction. In contrast, exercise training is a well known strategy to improve endothelial function. Thus, we hypothesized that:
Muscle vasodilatation during exercise is attenuated in individuals homozygous for the T allele, and
Exercise training would improve muscle vasodilatation in response to exercise in carriers of the TT genotype.
Methods: From 108 pre-selected healthy individuals genotyped for the T786C polymorphism by the PCR-RFLP method, 31 participated in the study. According to their genotype, the subjects were divided into 2 groups: TT (n=24; age 28±1 years) and CC (n=7; age 29±2 years). Forearm blood flow was evaluated by venous occlusion plethysmography and blood pressure by oscillometric automatic cuff at rest and during 30% handgrip exercise. Exercise training consisted of 3 sessions a week for six months, with intensity ranging from anaerobic threshold to respiratory compensation point.
Results: There was no significant difference between groups in age, BMI, and lipids profile. Resting forearm vascular conductance (FVC, P =0.36) and mean blood pressure (P =0.47) were similar between groups. However, FVC responses during handgrip exercise were significantly lower in TT individuals when compared to CC individuals (0.24 vs. 1.02 units, P=0.02). Exercise training significantly increased peak VO2 in both groups. Resting FVC was unchanged by exercise training. This intervention significantly increased FVC response to handgrip exercise in TT individuals (P=0.02), but not in CC individuals (P=0.88). The comparison between groups showed that FVC response was no longer different between TT and CC individuals (0.95 vs. 0.93 units, P=0.92).
Conclusions: Exercise training improves muscle vasodilatation in response to exercise in individuals homozygous for the T allele of polymorphism T786C. Therefore, this finding suggests that genetic variants influence vascular function as well as the response that interventions such as exercise training might have on this complex phenotype.