Developmental changes in hepatic basolateral membrane lipid composition and fluidity.
Membrane fluidity and lipid composition influence the activity of a variety of membrane proteins. Decreased rates of hepatic ion clearance are associated with the neonatal period. We postulated that hepatic basolateral membranes derived from suckling animals might be less fluid than those from adult animals. Basolateral membrane vesicles were prepared from the livers of 1-week-old (SBLMV) and adult (ABLMV) rats by a Percoll gradient method. Na+/K(+)-ATPase activities were similar in the two groups. Double bond index, cholesterol and cholesterol/phosphorus ratios were significantly higher in SBLMV compared with ABLMV, while lipid phosphorus and relative percentages of phospholipid subclasses did not differ. Fluorescence anisotropy measured using diphenylhexatriene as well as 2-(9-anthroyloxy)stearate was significantly greater in SBLMV compared with ABLMV, while measurements made with 12-(9-anthroyloxy)stearate were similar in both age groups. Mean excited state lifetimes, lifetime distributions, and rotational correlation times were similar in both groups. These data suggest that hepatic basolateral membranes derived from suckling rats are less fluid than those from adult animals and further suggest that this difference may be due to increased cholesterol in hepatic basolateral membranes derived from suckling animals.
Novak
D
D
Department of Pediatrics, University of South Florida College of Medicine, Tampa.
Ray
W
W
Carver
J
J
Grossman
S
S
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis; D005454:Fluorescence Polarization; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D005227:Fatty Acids; D008563:Membrane Lipids