Uric Acid, Xanthine Oxidase and Other Risk Factors of Hypertension in Normotensive Subjects

Abstract

Uric acid produced by xanthine oxidase (also a source of superoxide radicals) has been known to increase in hypertensive patients. In this study we evaluated the possible involvement of uric acid and xanthine oxidase in the pathogenesis of hypertension by examining their association with mean arterial pressure (MAP) and factors related to blood pressure. These factors include age, quetelet index (weight/height2), cholesterol, creatinine, calcium (Ca), magnesium (Mg), sodium (Na), potassium (K) and urea. Fifty Two (male-19, female-33) normal healthy individuals were studied. Correlation studies of demographic variables showed that age was positively correlated with MAP [r = 0.309, p = 0.026] and cholesterol [r = 0.503, p = 0.000] while quetelet index was positively correlated with age [r = 422, p = 0.000] MAP [r = 0.331, p = 0.016] and xanthine oxidase [r = 0.331, p = 0.016]. MAP was positively correlated with uric acid [r = 0.511, p = 0.000], cholesterol [r = 0.492, p = 0.000] and xanthine oxidase enzyme activity [r = 0.388, p = 0.004] and negatively correlated with plasma calcium [r = 0.603, p = 0.000]. Correlation studies of measured parameters with uric acid and xanthine oxidase showed that uric acid was positively correlated with creatinine [r = 0.627, p = 0.000], plasma magnesium [r 0.442, p = 0.001] and negatively correlated with plasma calcium [r = 0.546, p = 0.000] while xanthine oxidase was negatively correlated with plasma calcium [r = -0.404, p = 0.003] and plasma sodium [r = -0.288, p = 0.038]. Stepwise multiple regression with MAP as dependent variable showed that 65% of total variability of blood pressure can be accounted for by plasma calcium, cholesterol, creatinine, plasma K, plasma Na, uric acid and xanthine oxidase in order of increasing R2 [xanthine oxidase: T-value = 3.26, R2 = 0.653]. It can be concluded that in normotensive subjects, uric acid and xanthine oxidase have significant association with blood pressure and thus are one of the many factors which are involved in the cause or effect of hypertension.

Oxygen radical inhibition of nitric oxide-dependent vascular function in sickle cell disease

“…Plasma uric acid and XO levels are strongly predictive of hypertension in normotensive subjects (64). Although hypertension is not associated with SCD, sickle patients with high blood pressure have an increased risk of stroke and death (65).…”

Estrogen Modulates Xanthine Dehydrogenase/Xanthine Oxidase Activity by a Receptor-Independent Mechanism

“…XDH/XO is believed to be involved in the pathogenesis of diseases such as systemic hypertension (29), pulmonary hypertension (20,41), ischemia-reperfusion injury (16,33), and ARDS (34). Therefore, factors that modulate the metabolism and activity of XDH/XO may play a role in the pathogenesis or therapy of these disorders.…”

Increased Kidney Xanthine Oxidoreductase Activity in Salt-Induced Experimental Hypertension

“…7,8 A significant association of plasma urate and xanthine oxidoreductase (XOR) activity with mean arterial blood pressure has been observed in clinical studies among normotensive individuals. 9 Urate is produced in purine catabolism from the ATP degradation products xanthine and hypoxanthine by XOR, which occurs as xanthine dehydrogenase (XDH, EC 1.1.1.204) and xanthine oxidase (XO, EC 1.2.3.2). 10 In humans, urate is the end metabolite, whereas in rats urate is further oxidized to allantoin.…”