[Molecular and cellular mechanisms of ischemic damage of the brain in hemorrhagic shock].

General lightening of caryoplasma, the appearance of destructive areas in which electron-optic density was undetectable, ruptures in chromatin chains, changes in the nature of structural organization of euchromatic areas at the expense of density redistribution have been found in the nuclei of brain cortex oligodendrogliocytes and astrocytes by electron microscopy of caryoplasma of the nuclei from light neurons during experiments on anesthetized adult mongrel dogs weighing 9 to 26 kg recovered after a 4-hour hemorrhagic shock (BP 40 mm Hg). The nuclei of dark neurons and oligodendrogliocytes had matrix structure similar to control. The nuclei of astrocytes had marked matrix lightening with the formation of large zones in which electron-optic density was undetectable. It is evident that the degree of chromatin destruction in different neurons was not identical in hemorrhagic shock and depended on the functional neuronal activity. It has been established that there is a significant increase in the activity of nuclear Ca2+, Mg(2+)-depended endonucleases associated with chromatin and irreversibly cleaving ds- and ss-chromatin DNA chains. We believe that an increase in Ca2+, Mg(2+)-depended DNA-endonuclease activity should be considered an important pathogenetic factor in destructive processes that take place in the nuclei of brain cortex neurons in severe hemorrhagic shock.