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 h ypertensives, we investigated the relationship between the marker of oxidat ive DNA damage, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), and cardiovas cular risk factors, such as hypertension and serum glycosylated hemoglobin (HbA(1c)), among Tanzanians aged 46-58 years who were not on antihypertensi ve medication. Design and methods Sixty subjects (males/females, 28/ 32) were selected ran domly from the subjects who completed a 24h urine collection in our epidemi ological study at Dar es Salaam, Tanzania in 1998, The subjects were divide d into two groups, hypertensive subjects (systolic blood pressure (SBP) gre ater than or equal to 140 mmHg and/or diastolic blood pressure (DBP) greate r than or equal to 90 mmHg) and normotensive subjects (SBP < 140 mmHg and D BP < 90 mmHg) or hyperglycemic subjects (HbA(1c) greater than or equal to 6 .0%) and normoglycemic subjects (HbA(1c) < 6.0%), Biological markers from u rine 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). Uri nary 8-OHdG was significantly higher in hyperglycemic subjects than in norm oglycemic 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 hyp ertensive subjects, and there is a positive correlation between the level o f blood glucose estimated as HbA(1c) and oxidative DNA damage. Hyperglycemi a related to insulin resistance in hypertension in Tanzania is associated w ith increased urinary 8-OHdG. <(c)> 2001 Lippincott Williams & Wilkins.