Low density lipoprotein and apoprotein B induce increases in inositol trisphosphate and cytosolic free Ca2+ via pertussis toxin-sensitive GTP-binding protein in vascular smooth muscle cells.
Low density lipoprotein (LDL), a major cholesterol-carrying lipoprotein in the plasma, binds to its receptor through apoprotein B (Apo-B). The addition of LDL and Apo-B induced rapid (5 s), but transient increase in the inositol 1,4,5-trisphosphate (Ins-1,4,5-P3) level with K0.5 values of 1.1 and 0.07 microgram/ml, accompanied by increases of cytosolic free Ca2+ concentration [( Ca2+]i), in vascular smooth muscle cells (VSMC). The increases by LDL and Apo-B were both reduced by pretreatment of the VSMC with pertussis toxin. The early change in Ins-1,4,5-P3 involving a GTP-binding protein may function as an initial signal for the action of LDL in VSMC.
Morita
R
R
Department of Geriatric Medicine, Osaka University Medical School, Japan.
Morimoto
S
S
Koh
E
E
Fukuo
K
K
Kim
S
S
Itoh
K
K
Taniguchi
K
K
Onishi
T
T
Ogihara
T
T
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism; D001055:Apolipoproteins B / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004336:Drug Antagonism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D013403:Sugar Phosphates / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D001055:Apolipoproteins B; D007295:Inositol Phosphates; D008077:Lipoproteins, LDL; D013403:Sugar Phosphates; D010566:Virulence Factors, Bordetella; D015544:Inositol 1,4,5-Trisphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D002118:Calcium