The endothelial nitric oxide synthase −786 T>C polymorphism and the exercise-induced blood pressure and nitric oxide responses among men with elevated blood pressure

ObjectiveA polymorphism (−786 T>C) in the promoter region of the endothelial nitric oxide synthase gene (eNOS) has important functional characteristics. We examined the influence of eNOS −786 T>C (rs2070744) on the BP and NO response to acute dynamic exercise.MethodsSubjects (n = 49, 43.7 ± 1.4 yr) had pre- to Stage-1 hypertension (145.6 ± 1.5/85.9 ± 1.1 mmHg). Volunteers performed three experiments; a non-exercise control session, and two cycle exercise bouts at 40% (LIGHT) and 60% (MODERATE) of peak oxygen consumption. Subjects wore an ambulatory BP monitor upon leaving the laboratory. NO was measured by chemiluminescence assay before (baseline), during, and after the experiments. eNOS genotypes were determined by polymerase chain reaction and restriction enzyme digestion. Repeated measure ANOVA tested if BP and NO differed over time among experiments and by eNOS genotypes (n = 25, TT; n = 24, TC/CC).ResultsAmong carriers of the eNOS C786 allele, systolic BP (SBP) was reduced 5.3 ± 2.4 mmHg after MODERATE versus non-exercise control over 9 h compared to those with the eNOS T786T genotype (p < 0.05). Under these conditions, SBP tended to be lower 4.6 ± 2.9 mmHg after LIGHT (p = 0.076). The exercise-induced diastolic BP and NO responses were not different from non-exercise control between eNOS genotype (p > 0.05).ConclusionMen who were carriers of the eNOS C786 allele responded more favorably to the antihypertensive effects of aerobic exercise than men with the eNOS T786T genotype. The eNOS C786 allele is associated with reduced eNOS gene transcription and promoter activity. Future work is needed to determine how exercise may override genetic predispositions to down regulate eNOS gene activity.