Abstract
Summary
Spin-labeled stearic acid probes were incorporated into rat liver plasma membrane purified by a zonal centrifugation procedure. Temperature effects on the order parameter calculated from the spectra indicated the possible presence of a membrane phase transition at 20°, in agreement with earlier studies in other systems. Addition of Ca2+ (1.96 mM) at 37° increased the order parameter by 6.0 ± 0.7%, suggesting a Ca2+-mediated decrease in membrane fluidity.
The authors wish to thank Dr. Arne N. Wick for the use of his facilities and for his encouragement; Dr. Robert S. Livingston, Dr. Robert P. Metzger, Judy Esgate, and Richard Crosland for advice and reading the manuscript; and Dr. John A. Parsons for assistance with the phase contrast microscopic examinations. This study was supported in part by U. S. Public Health Service Grant 5685-12 to Dr. Arne N. Wick.
Get full access to this article
View all access options for this article.