title: Dopamine modulates von Willebrand factor secretion in endothelial cells via D2-D4 receptors.
abstract: OBJECTIVE
  von Willebrand factor (VWF) is acutely released from endothelial cells in response to numerous calcium-raising agents (e.g. thrombin, histamine) and cAMP-raising agents (e.g. epinephrine, adenosine, vasopressin). In contrast, very few inhibitors of endothelial VWF secretion have been described. The neurotransmitter dopamine is a modulator of exocytosis in several endocrine cells, and is possibly involved in the regulation of several endothelial cell functions. We therefore investigated the effect of dopamine on endothelial VWF secretion.
  
  
  RESULTS
  Dopamine, D2/D3- and D4-specific agonists inhibited histamine- but not thrombin-induced VWF secretion. Expression of dopamine D2, D3 and D4 receptors was demonstrated by reverse transcription polymerase chain reaction (RT-PCR) in both human aortic (HAEC) and umbilical vein (HUVEC) endothelial cells. D2-D4 agonists did not inhibit histamine-induced rise in [Ca(2+)](i): they inhibited histamine-induced secretion even in the absence of extracellular calcium. Thus, the dopamine effects are not mediated by [Ca(2+)](i)-dependent signalling. D2/D3- and D4-specific agonists inhibited neither the rise in cAMP nor VWF secretion in response to epinephrine and adenosine, arguing against an effect on cAMP-mediated signalling. D1 and D5 receptors were not detected in HAEC or HUVEC by RT-PCR, and the D1/D5-specific agonist SKF 38 393 failed to modulate VWF secretion, arguing against a role for these receptors in endothelial exocytosis.
  
  
  CONCLUSIONS
  Dopamine inhibits histamine-induced endothelial exocytosis by activating D2-D4 receptor, via a mechanism distinct from [Ca(2+)](i)-or cAMP-mediated signaling. In contrast, D1 and D5 receptors are not functionally expressed in cultured endothelial cells. Dopamine agonists may be useful as inhibitors of endothelial activation in inflammation and cardiovascular disease.
authors.affiliation: Department of Rehabilitation and Geriatrics, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, 1211 Geneva 4, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Zarei
authors.forename: M
authors.initials: M
authors.lastname: Frieden
authors.forename: B
authors.initials: B
authors.lastname: Rubi
authors.forename: P
authors.initials: P
authors.lastname: Villemin
authors.forename: B R
authors.initials: BR
authors.lastname: Gauthier
authors.forename: P
authors.initials: P
authors.lastname: Maechler
authors.forename: U M
authors.initials: UM
authors.lastname: Vischer
mesh_terms: D001011:Aorta / Q000166:cytology; D002478:Cells, Cultured; D004298:Dopamine / Q000502:physiology*; D018491:Dopamine Agonists / Q000494:pharmacology; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D005089:Exocytosis; D006632:Histamine; D006801:Humans; D011954:Receptors, Dopamine / Q000502:physiology*; D017448:Receptors, Dopamine D2 / Q000502:physiology; D050637:Receptors, Dopamine D3 / Q000502:physiology; D050638:Receptors, Dopamine D4 / Q000502:physiology; D015398:Signal Transduction; D014471:Umbilical Veins / Q000166:cytology; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D018491:Dopamine Agonists; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D014841:von Willebrand Factor; D050638:Receptors, Dopamine D4; D006632:Histamine; D004298:Dopamine