Uric acid is closely linked to vascular nitric oxide activity. Evidence for mechanism of association with cardiovascular disease.

OBJECTIVES: The study was undertaken to determine whether the mechanism of association of elevated serum uric acid level (SUA) with cardiovascular disease (CVD) is secondary to a common link with vascular nitric oxide (NO) activity.
BACKGROUND: Epidemiologic studies demonstrate an association of elevated SUA with CVD. The mechanism of this association is unknown, but both may be linked via an impairment in vascular NO activity. To examine this, we determined the relationship of SUA to vascular NO activity and to CVD risk. We then determined the effect of enhancing vascular NO activity on SUA.
METHODS: In part 1, individuals with various degrees of CVD (n = 458) were surveyed and underwent measurement of flow-mediated brachial artery vasodilation (FMV), a measure of vascular NO activity. In part 2, we performed an analysis of data pooled from six separate clinical trials of a medical food designed to enhance vascular NO activity in individuals with CVD (n = 217 subjects representing 253 treatment periods) to determine the effect on SUA.
RESULTS: In part 1, of all risk factors tested, SUA was second only to age in correlation with FMV, accounting for 7% (p < 0.0001) of the variability in FMV. Both SUA and FMV were related to the degree of disease risk (p < 0.0001 and p = 0.00025 by analysis of variance, respectively). By multivariate analysis, SUA did not continue to contribute significantly to the determination of FMV. In part 2, enhancement of FMV (5.8 +/- 4 to 8.6 +/- 5, p < 0.0001) was associated with a decrease in SUA (5.5 +/- 1.5 to 5.0 +/- 1.5, p < 0.0001). There was no placebo effect on FMV or SUA.
CONCLUSIONS: These results suggest that the association of elevated SUA with CVD may be a consequence of an impairment of vascular NO activity. This may be owing to an ability of NO to modulate uric acid production through its influence on xanthine oxidase activity.