Renal Excretion of 8-Oxo-7,8-dihydro-2′-deoxyguanosine in Wistar Rats with Increased O2 Consumption Due to Cold Stress

DNA damage by reactive oxygen species is of special interest in the development of cancer and in aging. The renally excreted amount of 8-oxo-7,8-dihydro-2′-deoxyguanosine (oxo8dG) is a potential noninvasive marker of oxidative DNA damage. The respiratory chain of mitochondria is one source for the formation of reactive oxygen species. In the present study we investigated in Wistar rats (n = 7; mean body weight at start, 307.4 ± 11 g) the effect of an increased O2 consumption, i.e., energy expenditure, due to cold stress on the renally excreted amount of oxo8dG. First, the rats were housed for 4 days at 23.5°C (basic period, BP), and then for 6 days at 10°C (cold stress period, CSP), and finally for 3 days at 23.5°C (recovery period, RP). The O2 consumption (L O2/day/kg weight) was significantly (P < 0.0001) on average 50% higher in CSP (69.0 ± 3.9) than in BP (45.8 ± 4.8), and similar in BP and RP (44.3 ± 5.4). The average renal excretion of oxo8dG (pmol/day/kg weight) was significantly (P < 0.025) on average 13% higher in CSP (375.5 ± 27.7) than in BP (333.2 ± 47.4) and similar in BP and RP (331.8 ± 34.3). Maximum increase in oxo8dG excretion of on average 17% was on the third to fifth day of the CSP. This study reveals that an increase in O2 consumption of 50% resulted in a much lower increase in the renal excretion of oxo8dG.