Renal excretion of 8-oxo-7,8-dihydro-2 '-deoxyguanosine in Wistar rats with increased O-2 consumption due to cold stress

DNA damage by reactive oxygen species is of special interest in the develop ment of cancer and in aging. The renally excreted amount of 8-oxo-7,8-dihyd ro-2'-deoxyguanosine (oxo(8)dG) is a potential noninvasive marker of oxidat ive 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 effe ct of an increased O-2 consumption, i.e,, energy expenditure, due to cold s tress on the renally excreted amount of oxo(8)dG. First, the rats were hous ed for 4 days at 23.5 degrees C (basic period, BP), and then for 6 days at 10 degrees C (cold stress period, CSP), and finally for 3 days at 23.5 degr ees C (recovery period, RP), The O-2 consumption (L O-2/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 oxo(8)dG (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 oxo(8)dG excretion of on average 17% was on the third to fifth day of the CSP, This study reveals that an increase in O-2 consumption of 50% resulted in a muc h lower increase in the renal excretion of oxo(8)dG. (C) 2000 Academic Pres s.