Jaci L. Van Heest

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.

OBJECTIVE A 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. METHODS Subjects (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). RESULTS Among carriers of the eNOS C(786) allele, systolic BP (SBP) was reduced 5.3+/-2.4 mmHg after MODERATE versus non-exercise control over 9h 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). CONCLUSION Men who were carriers of the eNOS C(786) allele responded more favorably to the antihypertensive effects of aerobic exercise than men with the eNOS T786T genotype. The eNOS C(786) 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.

The Metabolic Syndrome and the immediate antihypertensive effects of aerobic exercise: a randomized control design.

BackgroundThe metabolic syndrome (Msyn) affects about 40% of those with hypertension. The Msyn and hypertension have a common pathophysiology. Exercise is recommended for their treatment, prevention and control. The influence of the Msyn on the antihypertensive effects of aerobic exercise is not known. We examined the influence of the Msyn on the blood pressure (BP) response following low (LIGHT, 40% peak oxygen consumption, VO2peak) and moderate (MODERATE, 60% VO2peak) intensity, aerobic exercise.MethodsSubjects were 46 men (44.3 ± 1.3 yr) with pre- to Stage 1 hypertension (145.5 ± 1.6/86.3 ± 1.2 mmHg) and borderline dyslipidemia. Men with Msyn (n = 18) had higher fasting insulin, triglycerides and homeostasis model assessment (HOMA) and lower high density lipoprotein than men without Msyn (n = 28) (p < 0.01). Subjects consumed a standard meal and 2 hr later completed one of three randomized experiments separated by 48 hr. The experiments were a non-exercise control session of seated rest and two cycle bouts (LIGHT and MODERATE). BP, insulin and glucose were measured before, during and after the 40 min experiments. Subjects left the laboratory wearing an ambulatory BP monitor for the remainder of the day. Repeated measure ANCOVA tested if BP, insulin and glucose differed over time among experiments in men without and with the Msyn with HOMA as a covariate. Multivariable regression analyses examined associations among BP, insulin, glucose and the Msyn.ResultsSystolic BP (SBP) was reduced 8 mmHg (p < 0.05) and diastolic BP (DBP) 5 mmHg (p = 0.052) after LIGHT compared to non-exercise control over 9 hr among men without versus with Msyn. BP was not different after MODERATE versus non-exercise control between Msyn groups (p ≥ 0.05). The factors accounting for 17% of the SBP response after LIGHT were baseline SBP (β = -0.351, r2 = 0.123, p = 0.020), Msyn (β = 0.277, r2 = 0.077, p = 0.069), and HOMA (β = -0.124, r2 = 0.015, p = 0.424). Msyn (r2 = 0.096, p = 0.036) was the only significant correlate of the DBP response after LIGHT.ConclusionMen without the Msyn respond more favorably to the antihypertensive effects of lower intensity, aerobic exercise than men with the Msyn. If future work confirms our findings, important new knowledge will be gained for the personalization of exercise prescriptions among those with hypertension and the Msyn.