title: Circulating endocannabinoid concentrations during orthostatic stress.
abstract: BACKGROUND
  In animals, the endocannabinoid system is activated during hemodynamic insults and restrains blood pressure in part through sympathetic inhibition.
  
  
  METHODS
  We tested the hypothesis that hemodynamic stress elicited by head-up tilt testing increases systemic endocannabinoid concentrations in humans and that excessive endocannabinoid availability predisposes to presyncope.
  
  
  RESULTS
  With head-up tilt, 2-arachidonoylglycerol increased, whereas anandamide remained unchanged.
  
  
  CONCLUSIONS
  In contrast to our expectations, anandamide plasma concentration at rest was directly correlated with orthostatic tolerance, rather than intolerance.
authors.affiliation: Franz Volhard Clinical Research Center, Helios Klinikum-Berlin and Max Delbrück Center for Molecular Medicine, Berlin, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schroeder
authors.forename: Sandor
authors.initials: S
authors.lastname: Batkai
authors.forename: Stefan
authors.initials: S
authors.lastname: Engeli
authors.forename: Jens
authors.initials: J
authors.lastname: Tank
authors.forename: André
authors.initials: A
authors.lastname: Diedrich
authors.forename: Friedrich C
authors.initials: FC
authors.lastname: Luft
authors.forename: Jens
authors.initials: J
authors.lastname: Jordan
mesh_terms: D000328:Adult; D001095:Arachidonic Acids / Q000097:blood*; D001794:Blood Pressure / Q000502:physiology; D063385:Cannabinoid Receptor Modulators / Q000097:blood*; D004244:Dizziness / Q000097:blood*; D063388:Endocannabinoids; D005260:Female; D005989:Glycerides / Q000097:blood*; D006801:Humans; D008297:Male; D054971:Orthostatic Intolerance / Q000097:blood; D053284:Polyunsaturated Alkamides / Q000097:blood*; D013312:Stress, Physiological; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013575:Syncope / Q000097:blood; D018667:Tilt-Table Test
chemical_list: D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D005989:Glycerides; D053284:Polyunsaturated Alkamides; C094503:glyceryl 2-arachidonate; C078814:anandamide