Cholesterol-rich rabbit serum modulates beta-adrenergic receptor density of human lymphocytes. A possible role of LDL-cholesterol.
The effect of in vitro treatment of human lymphocytes with rabbit cholesterol-rich serum (RCS) on the membrane microviscosity as well as on the beta-adrenergic receptor density has been investigated. RCS treatment of cells resulted in a 30% decrease of receptor density without any effect on membrane microviscosity. A complete recovery was observed incubating the RCS cells either with the "Active Lipids" (AL) or with heparin. The AL are a mixture of neutral lipids, phosphatidylcholine and phosphatidylethanolamine from hen egg yolk known to fluidify the cell membrane. The AL modified membrane microviscosity of control lymphocytes without altering their beta-receptor number. These observations support the proposition that beta-receptor density of human lymphocytes is not regulated by membrane microviscosity and suggest that probably low density lipoprotein-cholesterol complex is involved in such a regulation.
Pieri
C
C
Gerontological Research Department, Italian National Research Centers on Aging (INRCA), Ancona.
Moroni
F
F
Recchioni
R
R
Falasca
M
M
Marcheselli
F
F
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D008078:Cholesterol, LDL / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000494:pharmacology; D008214:Lymphocytes / Q000378:metabolism*; D008560:Membrane Fluidity; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
D008078:Cholesterol, LDL; D008055:Lipids; D011943:Receptors, Adrenergic, beta; D006493:Heparin