The inverse association of elevated serum bilirubin levels with subclinical carotid atherosclerosis.

BACKGROUND: Serum bilirubin is negatively associated with the development of coronary heart disease. In the present study, we have focused on the analysis of intima-media thickness (IMT) of the common carotid artery in hyper- and normobilirubinemic subjects. METHODS: The study was performed on 111 men without manifested atherosclerosis. In all subjects, complete biochemical tests were determined along with the examination of IMT by carotid ultrasound. RESULTS: The mean IMT in hyperbilirubinemic subjects as compared with controls was substantially lower (p=0.017), and hyperbilirubinemic men also had very low age-adjusted prevalence odds ratios for having IMT above the 50th percentiles of controls, even after adjustment for selected vascular risk factors (p=0.034). CONCLUSIONS: In the present study, we demonstrate the inverse relationship between serum bilirubin and IMT in healthy men.

Relation between actual heart rate and autonomic effects of beta blockade in healthy men.

This study evaluated the effect of beta blockade on cardiac autonomic control and its dependence on heart rate change. The relations between RR interval duration, heart rate variability (HRV), and baroreflex sensitivity (BRS) were studied in 111 healthy men and in 21 male volunteers before and after a 100-mg oral dose of metoprolol. HRV and BRS correlated significantly with mean RR (r = 0.39, r = 0.57). Metoprolol administration increased both mean RR (from 996 to 1,176 ms, p <0.001), BRS from 24 to 36 ms/mm Hg (p = 0.003), and the SD of RR from 61 to 74 ms (p = 0.05). However, metoprolol-induced changes of HRV and BRS became insignificant (p = 0.69 and 0.48) after they were normalized to the same cycle length, suggesting that the improvement of cardiac autonomic control after beta blockade could be explained by a change of heart rate.