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894G>T polymorphism of endothelial nitric oxide synthase impairs hemodynamic responses to mental stress

Our aim was to evaluate the effect of the 894G>T polymorphism on the hemodynamic responses to mental stress performed before and after exercise. Subjects without (wild type, WT; n=16) or with (polymorphic type, PT; n=19) the polymorphism underwent a mental stress challenge before and after a bout of maximal dynamic exercise on a treadmill. Blood pressure and forearm blood flow were measured during mental stress. Before exercise, systolic blood pressure (SBP) response during mental stress was higher in the PT group (ΔWT: 8.0±2.0% vs. ΔPT: 12.5±1.8%, P=0.01), while the increase in forearm vascular conductance (FVC) was similar between the groups (ΔWT 90.8±26.4% vs. ΔPT: 86.3±24.1%, P=0.44). After exercise, the SBP at baseline and during mental stress was lower than before exercise in the whole group (P<0.05), but the pressure response during mental stress was still higher in the PT group (ΔWT: 5.8±1.5% vs. ΔPT: 10.2±1.4%, P=0.01). The increase in FVC was inhibited only in the PT group (Δbefore exercise 86.3±24.1% vs. Δafter exercise: 41.5±12.6%, P=0.04). In conclusion, subjects with the 894G>T polymorphism presented higher blood pressure response to mental stress, both before and after exercise along with blunted FVC increase after exercise. These results suggest that the 894G>T polymorphism is associated with altered hemodynamic responses to mental stress with potential clinical implications. Support: CNPq, FAPERJ, FINEP.