Background
: Atrial fibrillation (AF) has been shown to be associated with increased oxidative stress mediated by reactive oxygen species (ROS). Previous studies have proposed that there is a link between oxidative stress and AF, and thus oxidative stress may contribute to the pathological consequences of AF such as thrombosis, inflammation, and atrial tissue remodeling. Urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) which is a product of deoxyribonucleic acid (DNA) damage by ROS has become to be regarded as a putative biomarker of oxidative DNA damage. Also, biopyrrins which are oxdative metabolites of bilirubin (an important scavenger of ROS) are considered as the potential marker of oxdative stress. In the present study, we assessed serial changes in oxidative stress in patients with AF after cardioversion by measuring urinary 8-OHdG and urinary biopyrrin excretion.
Methods and Results
: The study subjects consisted of 15 patients with persistent or chronic AF, who underwent electrical or pharmacological cardioversion. We measured urinary 8-OHdG and biopyrrin levels obtained before cardioversion and 24 hours after cardioversion using enzyme-linked immunosorbent assay. There was no significant difference in the biopyrrin/creatinine levels before and 24 hours after cardioversion (3.2±2.6 vs. 3.3±2.4 mU/mg, P=NS). However, 8-OHdG/creatinine levels decreased significantly 24 hours after cardioversion (18.4±9.1 vs. 14.7±8.5 ng/mg, P=0.0012). There was no significant correlation between urinary 8-OHdG/creatinine and biopyrrin/creatinine levels. This discrepancy may be related to the difference in the time course between urinary 8-OHdG/creatinine and biopyrrin/creatinine levels. Thus, measurement of 8-OHdG/creatinine levels seemed to be a more useful marker which reflects the oxidative stress than biopyrrin/creatinine levels at the time 24 hours after cardioversion.
Conclusions
: These findings suggest that the restoration of sinus rhythm by cardioversion decreases oxidative DNA damage in AF patients, and urinary 8-OHdG may be useful for the estimation of oxidative stress in AF patients. The increase of oxidative stress may play an important role in the pathogenesis of AF, and persist AF and result in the perpetuation of AF.
Phthalate induced oxidative stress and DNA damage in earthworms (Eisenia fetida)
