Evidence against a role for ovarian hormones in the regulation of blood flow

ObjectiveTo determine the effect of ovarian hormone deficiency on peripheral vascular function.DesignRandomized, single-blind, placebo-controlled.SettingGeneral clinical research center.Patient(s)Twelve healthy, lean, premenopausal women with regular menstrual cycles.Intervention(s)Measurements were made during the early to midfollicular and midluteal phases of the menstrual cycle. Patients were then randomized to an 8-week course of gonadotropin-releasing hormone agonist (GnRHa) (n = 6) or placebo (n = 6) and retested. On each occasion, blood flow was assessed in the basal postabsorptive state and under euglycemic-hyperinsulinemic-hyperaminoacidemic conditions.Main Outcome Measure(s)Calf blood flow by venous occlusion plethysmography.Result(s)No differences in calf blood flow under postabsorptive (1.65 ± 0.09 vs. 1.73 ± 0.16 mL/100 g tissue per minute) or insulin-stimulated conditions (2.24 ± 0.20 vs. 2.30 ± 0.18 mL/100 g tissue per minute) were found between the follicular and luteal phases of the menstrual cycle, respectively; therefore, pretreatment data were averaged. Ovarian hormone suppression did not alter postabsorptive calf blood flow (GnRHa: 1.68 ± 0.13 to 1.69 ± 0.15; placebo: 1.69 ± 0.21 to 1.64 ± 0.14 mL/100 g tissue per minute) or the blood flow response to insulin infusion (GnRHa: 2.40 ± 0.21 to 2.37 ± 0.29; placebo: 2.10 ± 0.28 to 2.19 ± 0.35 mL/100 g tissue per minute).Conclusion(s)Variation in ovarian hormones associated with the menstrual cycle or short-term ovarian hormone deficiency induced by GnRHa do not affect calf blood flow under postabsorptive conditions or the response to hyperinsulinemia.