Reduced Local Heating-mediated Nitric Oxide-dependent Cutaneous Vasodilation In Firefighters Following A Structural Training Burn

Firefighters are at greater risk of sudden cardiac death, cardiovascular disease and certain cancers due to occupational exposure to numerous hazards. Toxicants present in structural fire smoke, including polycyclic aromatic hydrocarbons (PAHs), cause inflammation and oxidative stress resulting in vascular dysfunction in conduit vessels. Limited research is available in the skin vasculature, which may be susceptible to dysfunction resulting from dermal toxicant absorption. PURPOSE: Investigate the effects of a structural training burn on 1) Local heating (LH)-mediated cutaneous vasodilation and 2) the nitric oxide (NO) contribution to vasodilation during local heating due to its role in vascular health. METHODS: An intradermal microdialysis (MD) fiber was inserted in the ventral forearm of 7 male career firefighters (36 ± 7 yrs) within one week pre-burn and within 48 hours post-burn. The MD fiber was perfused with 10% 2-hydroxypropyl-β-cyclodextrin with lactated Ringer’s at 1 μl/min during baseline. A local heater housing a laser Doppler flowmeter was placed over the MD site to clamp skin temperature (Tsk) and assess skin blood flow (SkBf), respectively. Baseline Tsk was clamped at 33 °C then increased to 42 °C during LH. L-NAME (20 mM) was perfused at 4 μl/min to inhibit nitric oxide synthase until a plateau in SkBf occurred. Sodium nitroprusside was perfused at 4 μl/min and Tsk clamped at 43 °C to achieve maximal SkBf. RESULTS: No significant differences were observed in SkBf between pre- and post-burn at baseline (15 ± 8 vs. 22 ± 14 CVC%max, P = 0.242) or the LH plateau (90 ± 15 vs. 91 ± 8 CVC%max, P = 0.859). The L-NAME plateau was significantly higher post-burn (28 ± 12 vs. 36 ± 12 CVC%max, p = 0.044), resulting in a significantly attenuated LH-induced NO-dependent cutaneous vasodilation post-burn (69 ± 13 vs. 60 ± 12 CVC%max, P = 0.016). CONCLUSIONS: Participation in a single structural training burn attenuates LH-mediated NO-dependent cutaneous vasodilation in firefighters within 48-hours post exposure. This may have implications for long-term cardiovascular disease risk in firefighters and future exposure mitigation strategies. Supported by the Department of Public Health and Exercise Science, Appalachian State University