[Changes in the level, structure, and charges of rat serum lipoproteins during lengthy exposure to the cold]

The paper shows the results of complex investigation with the fluorescence techniques, electrophoresis a.o. methods of rat plasma lipoproteins in various terms (1 day-49 days) of cold exposure (+5 degrees C). There was the quantitative increase of the common fractions of VLDL and LDL to the 15 days of cold acclimation. The variations in percentage composition of LP occurred already on the first day. The changes of physico-chemical features of LP (surface charge and surface area, lipid viscosity and protein-lipid interactions did not always correspond to their quantitative changes and were not connected with lipid peroxidation. The decrease of the charges and the diminution of the surface area of VLDL, LDL and HDL were revealed on the first day. At 28-49 days the charges of VLDL and LDL were higher than in control, but LDL' one was lower. The occurred at this term decrease of efficiency of fluorescence energy transfer from LP' proteins to lipids, different variations of lipid viscosity demonstrated the less dip of proteins into lipids and/or the forming the aggregates of protein molecules. These in vivo LP modifications undoubtedly can induce the changes of their receptive and regulatory abilities.