Cyclooxygenase-1 And -2 Modulate Sweating But Not Cutaneous Vasodilation During Exercise In The Heat In Young Men

We recently reported that the nonselective cyclooxygenase (COX) inhibitor ketorolac attenuated sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat. However, the specific contributions of COX-1 and COX-2 to the sweating response remained to be determined. We tested the hypothesis that COX-1 but not COX-2 contributes to sweating with no role for either COX isoform in cutaneous vasodilation during moderate-intensity exercise in the heat. In thirteen young males (22 +/- 2 years), sweat rate and cutaneous vascular conductance were measured at three forearm skin sites that were continuously treated with (1) lactated Ringer's solution (Control), (2) 150 mu mmol.L-1 celecoxib, a selective COX-2 inhibitor, or (3) 10 mmol.L-1 ketorolac, a nonselective COX inhibitor. Participants first rested in a non heat stress condition (>= 85 min, 25 degrees C) followed by a further 70-min rest period in the heat (35 degrees C). They then performed 50 min of moderate-intensity cycling (similar to 55% peak oxygen uptake) followed by a 30-min recovery period. At the end of exercise, sweat rate was lower at the 150 mu mol.L-1 celecoxib (1.51 +/- 0.25 mg.min(-1).cm(-2)) and 10 mmol.L-1 ketorolac (1.30 +/- 0.30 mg.min(-1).cm(-2)) treated skin sites relative to the Control site (1.89 +/- 0.27 mg.min(-1).cm(-2)) (both P <= 0.05). Additionally, sweat rate at the ketorolac site was attenuated relative to the celecoxib site (P <= 0.05). Neither celecoxib nor ketorolac influenced cutaneous vascular conductance throughout the experiment (both P > 0.05). We showed that both COX-1 and COX-2 contribute to sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat in young men.