Anaphylactic histamine release and membrane fluidity of mast cells from young and aged rats

Abstract

The effect of aging on mast cell secretory function was studied in young (8 weeks old) and aged (72 weeks old) female BD6 rats using passive cutaneous anaphylaxis (PCA) and the histamine release testin vitro. Young rats were more susceptible to PCA and their peritoneal mast cells released more histamine in anin vitro anaphylactic reaction. Measurement of electron spin resonance (ESR) using methyl-5-doxylstearate and methyl-16-doxylstearate as spin labels demonstrated that cell membranes of mast cells of young rats showed higher fluidity in the resting state and a more pronounced increase in membrane fluidity after anaphylactic stimulation than mast cell membranes of aged rats. The study of lipid composition of mast cell membranes showed that the ratio of cholesterol (C) to phospholipids (P) was lower in mast cells of young rats than in mast cells of aged rats. This suggests that a decrease in membrane fluidity, associated with an increase in C/P ratio may be one of the factors responsible for decreased histamine releasability of mast cells from aged rats.