Effect of passive heat stress on arterial stiffness in smokers versus non-smokers

Abstract

In non-smokers, passive heat stress increases shear stress and vasodilation, decreasing arterial stiffness. Smokers, who reportedly have arterial dysfunction, may have similar improvements in arterial stiffness with passive heat stress. Therefore, we examined the effects of an acute bout of whole-body passive heat stress on arterial stiffness in smokers vs. non-smokers. Thirteen smokers (8.8 ± 5.5 [median = 6] cigarettes per day for > 4 years) and 13 non-smokers matched for age, mass, height, and exercise habits (27 ± 8 years; 78.8 ± 15.4 kg; 177.6 ± 6.7 cm) were passively heated to 1.5 °C core temperature (T C) increase. At baseline and each 0.5 °C T C increase, peripheral (pPWV) and central pulse wave velocity (cPWV) were measured via Doppler ultrasound. No differences existed between smokers and non-smokers for any variables (all p > .05), except cPWV slightly increased from baseline (526.7 ± 81.7 cm · s(-1)) to 1.5 °C ΔT C (579.7 ± 69.8 cm · s(-1); p < 0.005), suggesting heat stress acutely increased central arterial stiffness. pPWV did not change with heating (grand mean: baseline = 691.9 ± 92.9 cm · s(-1); 1.5 °C ΔT C = 691.9 ± 79.5 cm · s(-1); p > 0.05). Changes in cPWV and pPWV during heating correlated (p < 0.05) with baseline PWV in smokers (cPWV: r = -0.59; pPWV: r = -0.62) and non-smokers (cPWV: r = -0.45; pPWV: r = -0.77). Independent of smoking status, baseline stiffness appears to mediate the magnitude of heating-induced changes in arterial stiffness.

Hydration status influences the measurement of arterial stiffness

“…Independent of hydration status, we observed significant reductions in peripheral PWV during passive heating. Our findings indicate that differences in hydration status during heating do not explain why some research shows changes in PWV with passive heating (Ganio et al ., ) and some does not (Moyen et al ., ). There may be other reasons why we observed reductions in peripheral PWV with heat stress.…”

“…Also, many have proposed that changes in peripheral or central arterial stiffness during heat stress may be dependent upon normothermic arterial stiffness (Ganio et al, 2011;Kaldur et al, 2016;Moyen et al, 2016b). At a young age, the central, elastic, arteries are very compliant already, while the peripheral, muscular arteries are relatively stiff.…”

“…Further, subjects in this study only experienced mild dehydration, as defined by body mass loss (Cheuvront & Kenefick, ), during passive heating. Nonetheless, the amount of heat stress that subjects underwent is comparable to most studies involving passive heating (Ganio et al ., ; Kaldur et al ., ; Moyen et al ., ).…”

“…The importance of examining dehydration in conjunction with heat stress and PWV is highlighted by the increased research in this area (Brunt et al, 2016;Kaldur et al, 2016;Moyen et al, 2016b). With an acute exposure to passive heating, some studies have shown improvements in PWV (Ganio et al, 2011), but not all (Kaldur et al, 2016;Moyen et al, 2016b). Heat stress leads to dehydration (i.e.…”

“…a reduction in blood volume) if not fully compensated for with fluid intake. There is little evidence that prior studies investigating PWV and heat stress controlled hydration status prior to or during heat stress (Ganio et al, 2011;Kaldur et al, 2016;Moyen et al, 2016b). Given the variability of sweating between individuals and lack of control for hydration status, it is possible that varying levels of dehydration partially explain conflicting findings of studies examining the effect of heat stress on arterial stiffness.…”