This study examined the effects of different concentrations of centrophenoxine on physical properties of synaptic plasma membranes and liver microsomes using electron spin resonance procedures. Membranes of different age groups of mice were labeled with the 5-doxyl stearic acid spin-label and membrane fluidity determined in the presence and absence of different concentrations of centrophenoxine. Centrophenoxine had a direct effect on membranes as shown by a significant increase in membrane fluidity. This effect was greatest in liver microsomes as compared to synaptic plasma membranes. Age differences were not observed in centrophenoxine-induced fluidization. Effects of centrophenoxine in vivo may be due in part to the drug acting directly on the physical properties of the membrane lipid environment.
Bibliographical noteFunding Information:
This work was supported by the Medical Research Service of the Veterans Administration, USPHS Grant AA-02054 and the Geriatric Research, Education, and Clinical Center of the St. Louis Veterans Administration Medical Center. The authors gratefully acknowledge the excellent secretarial assistance of Cheryl Mason.