Forearm vasodilator responses to environmental stress and reactive hyperaemia are impaired in young South Asian men

Abstract

PurposePrevalence of cardiovascular disease (CVD) is greater in South Asians (SAs) than White Europeans (WEs). Endothelial dysfunction and blunted forearm vasodilatation to environmental stressors have been implicated in CVD. We investigated whether these features are present in young SA men.MethodsIn 15 SA and 16 WE men (19–23 years), we compared changes in forearm blood flow, arterial blood pressure (ABP), forearm vascular conductance (FVC), heart rate, and electrodermal resistance (EDR; sweating) following release of arterial occlusion (reactive hyperaemia endothelium-dependent) and 5 single sounds at 5–10 min intervals (stressors).ResultsAll were normotensive. Peak reactive hyperaemia was smaller in SAs than WEs (FVC increase: 0.36 ± 0.038 vs 0.44 ± 0.038 units; P < 0.05). Furthermore, in WEs, mean FVC increased at 5, 15, and 20 s of each sound (vasodilatation), but increased at 5 s only in SAs, decreasing by 20 s (vasoconstriction). This reflected a smaller proportion of SAs showing forearm vasodilatation at 15 s (5/15 SAs vs 11/16 WEs: P < 0.01), the remainder showing vasoconstriction. Concomitantly, WEs showed greater bradycardia and EDR changes. Intra-class correlation analyses showed that all responses were highly reproducible over five sounds in both WEs and SAs. Moreover, sound-evoked changes in ABP and FVC were negatively correlated in each ethnicity (P < 0.01). However, WEs showed preponderance of forearm vasodilatation and depressor responses; SAs showed preponderance of vasoconstriction and pressor responses.ConclusionsEndothelium-dependent vasodilatation is blunted in young SA men. This could explain their impaired forearm vasodilatation and greater pressor responses to repeated environmental stressors, so predisposing SAs to hypertension and CVD.

Endothelium-dependent and cyclooxygenase-dependent cutaneous vasodilatation is blunted in young men with hypertensive parents

“…Further, ACh-evoked dilatator responses though not reactive hyperaemia, were blunted in young SA, relative to WE men. Similarly, we recently showed that reactive hyperaemia and vasodilator responses to mental stress were blunted in forearm of young normotensive SA men, relative to WE men [36]. Moreover, FMD and the tonic dilator influence of NO on forearm were also blunted in young normotensive SA, relative to WE men [37].…”

The Burden of Atherosclerotic Cardiovascular Disease in South Asians Residing in Canada: A Reflection From the South Asian Heart Alliance

“…SAs are less likely to engage in physical activity, have lower daily consumption of fruits and vegetables, 32 have lower birth weights, which may be associated with increased blood pressure, 33 and may have underlying impairment of their endothelial vasodilation. 34 Generally, hypertension care appears to be similar between SAs and Caucasians, and the blood pressureelowering effect of antihypertensive therapy is similar in SAs as in other groups. 35,36 The management of hypertension in SAs should follow Hypertension Canada guidelines, with recognition of the higher risk of dysglycemia in SAs when selecting specific drugs.…”