Modulation of vascular tone control under isometric muscular stress: role of estrogen receptors.

AIMS: The aim of this study was to evaluate isometric muscle contraction (handgrip) changes on key elements of cardiac afterload, before and after raloxifene administration in postmenopausal women. METHODS/RESULTS: 12 postmenopausal and 12 fertile women were studied. Postmenopausal women underwent raloxifene administration (60 mg/day for 30 days). We evaluated vascular reactivity in superficial palmar arterial arch during handgrip in postmenopausal women before and after (M+R) drug administration, and in controls. Blood flow was higher after raloxifene administration (p<0.05). Mean arterial pressure (MAP)/mean arterial flow (Fmed) and arterial pulse pressure (APP)/systolic maximum arterial flow (Fmax syst) were lower after raloxifene administration (p<0.001). Systolic blood pressure (SBP)/R-R ratio was higher in postmenopausal women than in the controls and M+R (p<0.01). End-handgrip systolic and diastolic blood pressure were higher in patients before raloxifene administration than in controls (p<0.001); diastolic and mean arterial pressure reduced after raloxifene administration (p<0.001). End-effort APP/Fmax syst-ratio before treatment was higher than baseline (p<0.05). Controls and no-treated patients showed a MAP/Fmed ratio at end-handgrip higher than M+R group and rest (p<0.05). Handgrip reduced R-R interval and increased SBP/R-R ratio were shown in all groups (p<0.05). CONCLUSIONS: Raloxifene reduced the vascular effects of isometric muscle contraction by modulating the vasomotor tone of peripheral vessels in relation to exercise.