[Endothelial ultrastructure of myocardium microvessels affected by various methods of artificial hypothermia]

A comparative analysis of the endothelial ultrastructure of myocardium microvessels affected by various methods of artificial hypothermia was carried out. Tissue samples were harvested in children with a congenital ventricular septum defect after cooling the whole body under the conditions of hypothermic artificial circulation and perfusionless (immersion) hypothermia. It was found out that the shifts in population composition of endothelial cells, as well as the changes in the ultrastructure of organelles participating in endocellular syntheses and transendothelial transfer of macromolecules depended upon the rate body cooling. Under perfusionless hypothermia and of moderately low cooling rate, morphological signs of inhibition of endothelial cells metabolism were observed alongside with quantitative reduction of their micropinocytic transport indicators. Under hypothermic artificial circulation these reactions tended to lag behind due to the high cooling rate that initiates a heterogenic response of various endothelial processes to the changes of body temperature.