title: Mg2+ modulates membrane sphingolipid and lipid second messenger levels in vascular smooth muscle cells.
abstract: In vitro studies with smooth muscle cells from rat aorta and dog cerebral blood vessels indicate that variation in free Mg2+, within the pathophysiological range of Mg2+ concentrations, found in human serum, causes sustained changes in membrane phospholipids and lipid second messengers. Incorporation of [3H]palmitic acid into phosphatidylcholine (PC) and sphingomyelin (SM) was altered within 15-30 min after modifying the extracellular Mg2+ ion level ([Mg2+]o). Decreased Mg2+ produced a fall in both [3H]SM and [3H]PC over the first 2 h. After an 18-h incubation, the [3H]PC/[3H]SM ratio changed from about 20:1 to about 50:1. Increased [Mg2+]o resulted in a 2- to 3-fold increase in [3H]SM compared to only a small increase in [3H]PC over the same period. There was a reciprocal relationship between [3H]ceramide and [3H]1,2-DAG levels with highest [3H]ceramide and lowest [3H]-1,2-DAG levels seen at lowest [Mg2+]o. The results indicate that a fall in extracellular ionized Mg2+ concentration produces a rapid and sustained decrease in membrane sphingomyelin and a moderate rise in intracellular ceramide. A major effect of lowering [Mg2+]o appears to be a down-regulation of SM synthase. The increased membrane SM content and a concomitant decrease in cell ceramide, in the presence of elevated [Mg2+]o, may be relevant to the apparent protective role of adequate Mg intake on vascular function in humans.
authors.affiliation: Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Morrill
authors.forename: R K
authors.initials: RK
authors.lastname: Gupta
authors.forename: A B
authors.initials: AB
authors.lastname: Kostellow
authors.forename: G Y
authors.initials: GY
authors.lastname: Ma
authors.forename: A
authors.initials: A
authors.lastname: Zhang
authors.forename: B T
authors.initials: BT
authors.lastname: Altura
authors.forename: B M
authors.initials: BM
authors.lastname: Altura
mesh_terms: D000818:Animals; D001011:Aorta; D001921:Brain / Q000098:blood supply; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D004285:Dogs; D066298:In Vitro Techniques; D050356:Lipid Metabolism; D008274:Magnesium / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D019308:Palmitic Acid / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015290:Second Messenger Systems; D013109:Sphingomyelins / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
chemical_list: C011439:1,2-diacylglycerol; D002518:Ceramides; D004075:Diglycerides; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; D014280:Triglycerides; D019308:Palmitic Acid; D008274:Magnesium