Effect of Brief Ambient Cooling on Serum Stress Biomarkers in Older Adults During a Daylong Heat Exposure: A Laboratory-Based Heat Wave Simulation.

Abstract

Visiting an air-conditioned location during heat exposure reduces physiological strain, however the effects on gastrointestinal barrier dysfunction and renal ischemia remain unexplored. We compared serum protein responses during a 9-h heat exposure (40.3°C, 9.3% relative humidity) in 17 older adults without cooling (control) and 19 older adults with a cooling break (~23°C) during hours 5 and 6 (cooling). IFABP and sCD14 increased similarly across groups. NGAL was 3.2 pg/mL [1.9, 6.1] lower in the cooling group during heat exposure. A 2-h cooling centre exposure did not ameliorate gastrointestinal barrier dysfunction, but did a reduce a surrogate marker of renal ischemia.