[Thermal structural transitions in the membranes of fat cells]

Studies have been carried out of the structural state of plasma membranes of epididimal fat cells from rats at 5--40 degrees C. The temperature dependence of the fluorescence intensity bound ANS and the rate of solubilization by 0.2% sodium dodecyl sulfate have shown sharp changes at 19--24 degrees C. At the same temperature intervals there was a break in the Arrhenius curve for activity of the membrane 5'-nucleotidase. ANS fluorescence and light scattering of liposomes from membrane lipids have revealed discontinuities at 21 degrees and 29--30 degrees C. The data are interpreted as thermal rearrangements initiated in the lipid membrane phase.