Modulation of radiation-induced chromosome aberrations by DMSO, an OH radical scavenger. 1

Studies demonstrate that DMSO affects a concentration-dependent modulation of induced asymmetrical aberrations in human lymphocytes exposed to ∼ 3.0 Gy, with maximum protectible fractions of approximately 70% at DMSO concentrations of ≥ 1 M. Dose dependency for dicentrics in lymphocytes acutely exposed to X-ray doses of 0.51 to 4.98 Gy in the absence of DMSO is adequately described by the linear-quadratic dose-response function Y = αD + βD2. Data from duplicate cultures exposed in the presence of 1 M DMSO produce excellent fit to the regression function modified as follows: Y(+ DMSO) = α(ΔD) + β(ΔD)2 where 'dose modifying' factor Δ = 0.501. These results are seen as evidence that OH radical-mediated lesions in DNA account for ∼ 50% dose dependency for dicentrics resulting from either one-track or two-track events, following exposures of non-cycling cells to moderate-to-high doses of low LET radiation. These data may be used in calculations to derive an estimate of ∼ 6 x 108 s-1 for the rate of reaction of OH radicals with DNA targets involved in aberration formation. (author)