title: Extracellular calcium sensing in rat aortic vascular smooth muscle cells.
abstract: Extracellular calcium (Ca(2+)(o)) can act as a first messenger in many cell types through a G protein-coupled receptor, calcium-sensing receptor (CaR). It is still debated whether the CaR is expressed in vascular smooth muscle cells (VSMCs). Here, we report the expression of CaR mRNA and protein in rat aortic VSMCs and show that Ca(2+)(o) stimulates proliferation of the cells. The effects of Ca(2+)(o) were attenuated by pre-treatment with MAPK kinase 1 (MEK1) inhibitor, as well as an allosteric modulator, NPS 2390. Furthermore, stimulation of the VSMCs with Ca(2+)(o)-induced phosphorylation of ERK1/2, but surprisingly did not cause inositol phosphate accumulation. We were not able to conclusively state that the CaR mediates Ca(2+)(o)-induced cell proliferation. Rather, an additional calcium-sensing mechanism may exist. Our findings may be of importance with regard to atherosclerosis, an inflammatory disease characterized by abnormal proliferation of VSMCs and high local levels of calcium.
authors.affiliation: Laboratory of Molecular Cardiology, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Denmark.
authors.forename: Sanela
authors.initials: S
authors.lastname: Smajilovic
authors.forename: Jakob Lerche
authors.initials: JL
authors.lastname: Hansen
authors.forename: Tue E H
authors.initials: TE
authors.lastname: Christoffersen
authors.forename: Ewa
authors.initials: E
authors.lastname: Lewin
authors.forename: Søren P
authors.initials: SP
authors.lastname: Sheikh
authors.forename: E F
authors.initials: EF
authors.lastname: Terwilliger
authors.forename: Edward M
authors.initials: EM
authors.lastname: Brown
authors.forename: Stig
authors.initials: S
authors.lastname: Haunso
authors.forename: Jacob
authors.initials: J
authors.lastname: Tfelt-Hansen
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D002118:Calcium / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D044169:Receptors, Calcium-Sensing / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D044169:Receptors, Calcium-Sensing; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D048369:MAP Kinase Kinase 1; D002118:Calcium