[Effect of toluene on stability of chromatin of white rat hippocampus and olfactory bulb in vivo. Microcalorimetric study].

The denaturation heat parameters of hippocampus and olfactory bulb nodulus tissues were determined. The total denaturation heat calculated from the areas of endotherms I-IX onto which the dependence deltaH = f(T) is factorized equals to 13.03 +/- 1.3 J/g for bulb nodules and 9.91 J/g for the hippocampus. It was shown that chromatin in the composition of tissues had two stages of denaturation with the following parameters: for bulb nodules: Td(VIII) = 99.4 degrees C, Qd(VIII) = 62.3 +/- 0.8 J/g DNA, Td = (IX) = 106 degrees C, Qd = 28.8 ; 0.4 J/g DNA; and for hippocampus: Td(VIII) = 95 degrees C; Qd(VIII) = 62.0 +/- 9 J/g. Td(IX) - 107 degrees C; Qd(IX) = 29.0 +/- 4.5 J/g DNA. It was established that, along with denaturation of cytoplasmatic structures, nonhistone, nuclear proteins and damage to the nuclear matrix, toluene caused the redistribution of heat between endotherms IX, VIII, VIII(I) connected with the infolding of chromatin loops and 30-nm fibers. It is supposed that toluene causes the damage to the genetic material due to not only its oxidative influence on chromatin DNA but also the disturbance of nuclear matrix structural organization and partial denaturation of nuclear proteins of non-histone origin.