Exercise training improves endothelial function in resistance arteries of young prehypertensives

Abstract

Prehypertension is associated with reduced conduit artery endothelial function and perturbation of oxidant/antioxidant status. It is unknown whether endothelial dysfunction persists to resistance arteries and whether exercise training affects oxidant/antioxidant balance in young prehypertensives. We examined resistance artery function using venous occlusion plethysmography measurement of forearm (FBF) and calf blood flow (CBF) at rest and during reactive hyperaemia (RH), as well as lipid peroxidation (8-iso-PGF2α) and antioxidant capacity (Trolox-equivalent antioxidant capacity; TEAC) before and after exercise intervention or time control. Forty-three unmedicated prehypertensive and 15 matched normotensive time controls met screening requirements and participated in the study (age: 21.1±0.8 years). Prehypertensive subjects were randomly assigned to resistance exercise training (PHRT; n=15), endurance exercise training (PHET; n=13) or time-control groups (PHTC; n=15). Treatment groups exercised 3 days per week for 8 weeks. Peak and total FBF were lower in prehypertensives than normotensives (12.7±1.2 ml min(-1) per100 ml tissue and 89.1±7.7 ml min(-1) per 100 ml tissue vs 16.3±1.0 ml min(-1) per 100 ml tissue and 123.3±6.4 ml min(-1) per 100 ml tissue, respectively; P<0.05). Peak and total CBF were lower in prehypertensives than normotensives (15.3±1.2 ml min(-1) per 100 ml tissue and 74±8.3 ml min(-1) per 100 ml tissue vs 20.9±1.4 ml min(-1) per 100 ml tissue and 107±9.2 ml min(-1) per 100 ml tissue, respectively; P<0.05). PHRT and PHET improved humoral measures of TEAC (+24 and +30%) and 8-iso-PGF2α (-43 and -40%, respectively; P < or = 0.05). This study provides evidence that young prehypertensives exhibit reduced resistance artery endothelial function and that short-term (8 weeks) resistance or endurance training are effective in improving resistance artery endothelial function and oxidant/antioxidant balance in young prehypertensives.

Figure 1

Absolute values for forearm (FBF) and calf blood flow (CBF) at rest and during reactive hyperemia in prehypertensives vs. normotensives are presented. Between group comparisons at baseline were evaluated using a Satterthwaite correct t-test. *P<0.05, PH vs. NM; **P<0.01, PH vs. NM. Data are expressed as mean ± SEM.

Figure 2

Absolute values are presented as percent change from baseline for the exercise treated groups. P values are reported from within-group repeated measures ANOVA and Tukey post hoc analysis of between-group and between-timepoint differences in absolute values. Percent changes in FBF and CBF at rest and during reactive hyperemia are shown. *P<0.05, PHRT vs. PHET; †P < 0.01, PHRT vs. PHET, indicates significant differences between exercise trained groups after treatment. Data are expressed as mean ± SEM.

Figure 3

Absolute values for 8-isoprostane (8-iso-PGF_2α) and Trolox-equivalent antioxidant-capacity (TEAC) are presented. P values are from within group repeated measures ANOVA and Tukey post hoc analysis of between group and between timepoint differences in absolute values. *P<0.05 vs. NMTC at same timepoint; **P<0.01 vs. NMTC at same timepoint; †P<0.05 vs pretreatment values; ††P<0.01 vs. pretreatment values. Data are expressed as mean ± SEM.