Heat shock protein 90 does not contribute to cutaneous vasodilatation in older adults during heat stress

Abstract

Objectives Heat shock protein 90 (HSP90) contributes to cutaneous vasodilatation during exercise in the heat through nitric oxide (NO) synthase (NOS)–dependent mechanisms in young adults. We hypothesized that similar responses would be observed in older middle‐aged adults. Methods In nineteen habitually active older middle‐aged (56 ± 5 years) men (n = 9) and women (n = 10), cutaneous vascular conductance (CVC) was measured at four forearm skin sites continuously treated with (a) lactated Ringers solution (Control), (b) 10 mmol/L L‐NAME (NOS inhibitor), (c) 178 μmol/L geldanamycin (HSP90 inhibitor), or (d) 10 mmol/L L‐NAME and 178 μmol/L geldanamycin combined. Participants rested in an upright semi‐recumbent position in the heat (35°C) for 70 minutes, followed by a 50‐minute bout of moderate‐intensity cycling (~55% peak oxygen uptake) and a 30‐minute recovery period in the heat. Results In both men and women, we observed no significant effects of HSP90 inhibition on CVC throughout rest, exercise, and recovery in the heat (all P > 0.27). Conversely, NOS inhibition and dual NOS and HSP90 inhibition attenuated CVC relative to Control throughout the protocol (all P ≤ 0.05). Conclusions While NOS mediates cutaneous vasodilatation during rest, exercise, and recovery in the heat, HSP90 does not measurably influence this response in habitually active older middle‐aged men or women under these conditions.

Effects of short‐term heat acclimation on whole‐body heat exchange and local nitric oxide synthase‐ and cyclooxygenase‐dependent heat loss responses in exercising older men

“…To gain a better understanding of the mechanism(s) surrounding any improvements in heat dissipation, we also performed microdialysis trials before and after short‐term exercise–heat acclimation (Figure 1). Inhibition of NOS reduced cutaneous vascular conductance relative to the control site during exercise in the heat, with no effect of COX inhibition (Figure 3a), which is consistent with previous studies testing older adults (Fujii et al., 2015, 2016, 2019). Given that the contribution of NOS to cutaneous vasodilatation is greater in young relative to older men and women during passive heating at rest (Stanhewicz et al., 2012) and during exercise in the heat (Fujii et al., 2016), ageing appears to diminish the NOS contribution.…”

“…to the control site during exercise in the heat, with no effect of COX inhibition (Figure 3a), which is consistent with previous studies testing older adults (Fujii et al, 2015(Fujii et al, , 2016(Fujii et al, , 2019. Given that the contribution of NOS to cutaneous vasodilatation is greater in young relative to older men and women during passive heating at rest (Stanhewicz et al, 2012) and during exercise in the heat (Fujii et al, 2016), ageing appears to diminish the NOS contribution.…”