Exercise vasodilation is greater in women: contributions of nitric oxide synthase and cyclooxygenase.

Purpose: We hypothesized exercise vasodilation would be greater in women due to nitric oxide synthase (NOS) and cyclooxygenase (COX) signaling.

Methods: 45 healthy adults (23 women, W, 22 men, M, 26 ± 1 years) completed two 10-min trials of dynamic forearm exercise at 15 % intensity. Forearm blood flow (FBF; Doppler ultrasound), arterial pressure (brachial catheter), and forearm lean mass were measured to calculate relative forearm vascular conductance (FVCrel) = FBF 100 mmHg(-1) 100 g(-1) lean mass. Local intra-arterial infusion of L-NMMA or ketorolac acutely inhibited NOS and COX, respectively. In Trial 1, the first 5 min served as control exercise (CON), followed by 5 min of L-NMMA or ketorolac over the last 5 min of exercise. In Trial 2, the remaining drug was infused during 5-10 min, to achieve combined NOS-COX inhibition (double blockade, DB).

Results: Are mean ± SE. Women exhibited 29 % greater vasodilation in CON (ΔFVCrel, 19 ± 1 vs. 15 ± 1, p = 0.01). L-NMMA reduced ΔFVCrel (p < 0.001) (W: Δ -2.3 ± 1.3 vs. M: Δ -3.7 ± 0.8, p = 0.25); whereas, ketorolac modestly increased ΔFVCrel (p = 0.04) similarly between sexes (W: Δ 1.6 ± 1.1 vs. M: Δ 2.0 ± 1.6, p = 0.78). DB was also found to be similar between the sexes (p = 0.85).

Conclusion: These data clearly indicate women produce a greater exercise vasodilator response. Furthermore, contrary to experiments in animal models, these data are the first to demonstrate vascular control by NOS and COX is similar between sexes.