The relation of oxidative DNA damage to hypertension and other cardiovascular risk factors in Tanzania

Objectives To clarify the mechanism of involvement of oxidative stress in hypertensives, we investigated the relationship between the marker of oxidative DNA damage, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), and cardiovascular risk factors, such as hypertension and serum glycosylated hemoglobin (HbA(1c)), among Tanzanians aged 46-58 years who were not on antihypertensive medication. Design and methods Sixty subjects (males/females, 28/ 32) were selected randomly from the subjects who completed a 24h urine collection in our epidemiological study at Dar es Salaam, Tanzania in 1998, The subjects were divided into two groups, hypertensive subjects (systolic blood pressure (SBP) greater than or equal to 140 mmHg and/or diastolic blood pressure (DBP) greater than or equal to 90 mmHg) and normotensive subjects (SBP < 140 mmHg and DBP < 90 mmHg) or hyperglycemic subjects (HbA(1c) greater than or equal to 6.0%) and normoglycemic subjects (HbA(1c) < 6.0%), Biological markers from urine and blood were analyzed centrally in the WHO Collaborating Center. Results The mean levels of HbA(1c) and 8-OHdG were significantly higher in the hypertensive subjects than in the normotensive subjects (P < 0.05). Urinary 8-OHdG was significantly higher in hyperglycemic subjects than in normoglycemic subjects. HbA(1c) was positively correlated with the 24-h urinary 8-OHdG excretions (r= 0.698, P < 0.0001). Conclusions These findings suggest oxidative DNA damage is increased in hypertensive subjects, and there is a positive correlation between the level of blood glucose estimated as HbA(1c) and oxidative DNA damage. Hyperglycemia related to insulin resistance in hypertension in Tanzania is associated with increased urinary 8-OHdG. <(c)> 2001 Lippincott Williams & Wilkins.