title: Effects of nicotine on PTHrP and PTHrP receptor expression in rat coronary endothelial cells.
abstract: OBJECTIVE
  The study was aimed to investigate whether nicotine affects endothelial expression of PTHrP and PTHrP receptor, a peptide system involved in endothelial protection against apoptosis.
  
  
  METHODS
  Isolated and cultured rat coronary endothelial cells were used. Immunoblot techniques were used to study activation of mitogen-activated protein (MAP) kinases and to quantify PTHrP and PTHrP receptor expression. Real-time RT-PCR was used to quantify PTHrP, PTHrP-receptor, bcl-2, and bax mRNA expression. The rate of apoptosis was determined by HOE33258 staining and confirmed by quantification of the bcl-2-to-bax ratio. In vitro data were compared to hearts from rats exposed to cigarette smoking.
  
  
  RESULTS
  Nicotine induced PTHrP protein expression at nanomolar levels and small increases of PTHrP release (≈8%). Antagonists directed against the α7 subunit of cholinergic receptors, the most prominent isoform, attenuated nicotine-dependent increases of PTHrP expression. This effect of nicotine was p38 MAPK dependent. Nicotine at micromolar concentrations reduced PTHrP receptor expression. In vitro and in vivo we found a correlation between PTHrP receptor expression and bcl-2 expression.
  
  
  CONCLUSIONS
  Nicotine induces PTHrP expression in endothelial cells but excessive concentrations of nicotine reduce PTHrP receptor expression thereby attenuating any protective effects of PTHrP against apoptosis.
authors.affiliation: Justus-Liebig University, Department of Physiology, Gießen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Röthig
authors.forename: Rolf
authors.initials: R
authors.lastname: Schreckenberg
authors.forename: Kerstin
authors.initials: K
authors.lastname: Weber
authors.forename: Charlotte
authors.initials: C
authors.lastname: Conzelmann
authors.forename: Rui Manuel
authors.initials: RM
authors.lastname: da Costa Rebelo
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Schlüter
mesh_terms: D000818:Animals; D017209:Apoptosis; D006690:Bisbenzimidazole / Q000378:metabolism; D002038:Bungarotoxins / Q000494:pharmacology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation; D005419:Flavonoids / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D015151:Immunoblotting; D020935:MAP Kinase Signaling System; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C494828:Bax protein, rat; D002038:Bungarotoxins; D005419:Flavonoids; D007093:Imidazoles; D044162:Parathyroid Hormone-Related Protein; D011725:Pyridines; D012333:RNA, Messenger; D044168:Receptor, Parathyroid Hormone, Type 1; D051028:bcl-2-Associated X Protein; D009538:Nicotine; D048051:p38 Mitogen-Activated Protein Kinases; D006690:Bisbenzimidazole; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one