Low-dose ASA therapy does not alter core or skin temperature during hot-dry or warm-humid heat stress (PSU HEAT project)

Nearly 40% of US adults over the age of 50 use aspirin (ASA) therapy for the primary or secondary prevention of cardiovascular disease. Systemic platelet cyclooxygenase inhibition with low-dose ASA attenuates reflex cutaneous vasodilation and accelerates the rate of rise of core temperature during passive heating in middle-aged adults. The functional effect of low-dose ASA therapy on thermoregulatory and cardiovascular responses to hot and humid environmental extremes in older (>65 years) adults has not been determined. Eleven older adults (5F; 66–80 years) were exposed to progressive heat stress in an environmental chamber at a metabolic rate comparable to activities of daily living (~80 W∙m⁻²) in a warm-humid (WH; 36°C, 52% rh) and hot-dry (HD; 40°C, 21% rh) environment following 7 days of low-dose ASA (81 mg/day) or placebo. Core temperature (T_c), skin temperature (T_sk), heart rate (HR), mean arterial pressure (MAP) and forearm blood flow (FBF) were measured, and rate-pressure product was subsequently calculated. Low-dose ASA attenuated FBF and forearm vascular conductance (all p ≤ 0.04) but had no effect on T_c or T_sk in either environment. In conclusion, low-dose ASA attenuates the skin blood flow response during minimal activity heat stress in both dry and humid environments but does not alter T_c.