This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Keating, K. M. Articles by Roess, D. A. Search for Related Content PubMed PubMed Citation Articles by Keating, K. M. Articles by Roess, D. A.

Glucocorticoid Effects on Lipid Lateral Diffusion and Membrane Composition in Lipopolysaccharide-activated B-Cell Leukemia 1 Cells¹

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510; and Department of Chemistry and Microbiology and of Physiology, Colorado State University, Fort Collins, Colorado 80523

We have investigated the effects of glucocorticoid treatment on lipid lateral diffusion and cholesterol:phospholipid ratios in the plasma membranes of the lipopolysaccharide (LPS)-responsive murine B-cell leukemia (BCL₁). Exposure to LPS for 24 h at concentrations of 50 µg/ml, 100 µg/ml, and 250 µg/ml caused a 42% reduction in the lateral diffusion of the lipid probe 3,3'-dioctadecylindocarbocyanine iodide as measured by fluorescence photobleaching recovery techniques at 37°C. In cells incubated with 50 µg/ml LPS, 3,3'-dioctadecylindocarbocyanine iodide diffusion is reduced to 2.2 x 10^-9 cm²s^-1 compared to freshly isolated BCL₁ cells where 3,3'-dioctadecylindocarbocyanine iodide diffused at a rate of 3.8 x 10^-9 cm²s^-1. In BCL₁ cells activated by LPS for 24 h and recultured with a pharmacological concentration of the synthetic glucocorticoid triamcinolone acetonide (TA, 10^-6 M) for 6 h, lipid lateral diffusion increased to 3.5 x 10^-9 cm²s^-1. Concentrations of TA lower than 10^-6 M had no effect on lipid lateral diffusion. Six-h treatment with 10^-6 M TA had no effect on freshly isolated BCL₁ cells (Time 0). However, lipid lateral diffusion increased in cells incubated 24, 48, and 72 h with LPS, and an additional 6 h with 10^-5 M TA suggested that activated BCL₁ cells were more glucocorticoid sensitive than cells at Time 0. Plasma membrane cholesterol and phospholipid content, analyzed at 0 and 24 h, indicated that LPS activation was associated with a 7% increase in the cholesterol:phospholipid ratio in BCL₁ membranes and that glucocorticoid treatment of these LPS-activated cells for 6 h decreased the membrane cholesterol:phospholipid ratio perhaps through inhibition of de novo cholesterol synthesis.

¹ This work was supported by NIH AI-21873 (B. G. B.), by NIH HD 23236 (D. A. R.), and by the United States Department of Agriculture Animal Health and Disease program.

² To whom requests for reprints should be addressed, at the Department of Physiology, Colorado State University, Fort Collins, CO 80523.

Received 4/21/87. Revised 9/ 1/87. Accepted 10/ 7/87.