Is sustained post-exercise vasodilation associated with an exercise-induced mast cell activation? (1106.19)

An acute bout of aerobic exercise elicits a sustained post-exercise vasodilation which is histamine-receptor mediated. However, the source of the histamine which activates histamine receptors during recovery from exercise remains unknown. One possible source is degranulation of mast cells. We tested the hypothesis that tryptase, a marker of mast cell degranulation, is elevated during or after exercise. In 11 healthy subjects (6 men; 5 women), we measured interstitial tryptase via microdialysis of the vastus lateralis before, during, and through 90 min after exercise (1 hr of unilateral dynamic knee extension at 60% of peak power; 6 subjects) or rest (1 hr seated upright; 5 subjects). Compared with baseline, interstitial tryptase was increased more during exercise (Δ 60 ± 7%) than during rest (Δ 10 ± 9%, P < 0.05) and tended to remain elevated during recovery (exercise Δ 44 ± 14% vs rest Δ 16 ± 7%, P = 0.11). Thus, localized mast cell degranulation occurs in exercising muscle, and appears to contribute in ...