Association of serum bilirubin with pulsatile arterial function in asymptomatic young adults: the Bogalusa Heart Study

The inverse association between serum bilirubin, a potent antioxidant, and oxidative stress-mediated diseases like cardiovascular disease is known. However, information is scant regarding the influence of bilirubin in relation to traditional cardiovascular risk factors on pulsatile arterial function in asymptomatic younger adults. The present study examines this aspect in 777 black and white subjects (71% white, 42% male) aged 18 to 44 years. Pulsatile arterial function was assessed in terms of large-artery (capacitive) and small-artery (oscillatory) compliances by radial artery pressure pulse contour analysis. In bivariate analysis adjusted for race and sex, bilirubin related significantly and positively to large- and small-artery compliances and high-density lipoprotein cholesterol, and inversely to age, body mass index, blood pressure variables, non-high-density lipoprotein cholesterol, triglycerides, and insulin resistance index. In multivariable analysis including race, sex, body surface area, and risk factor variables mentioned above, bilirubin did not relate to large-artery compliance, without or with smoking status in the model, whereas bilirubin associated beneficially with small-artery compliance (P = .01) in a model that excluded smoking status. When smoking status was included in the model, this association became less strong (P = .04); and smoking entered the model as an adverse predictor (P = .003). The observed beneficial association of serum bilirubin on pulsatile arterial function, albeit the attenuating effect of smoking on this relationship, in asymptomatic younger adults supports the antioxidant function of bilirubin in providing protection against oxidative stress-mediated vascular dysfunction.