title: Serotonin concentrations in platelets, plasma, mitral valve leaflet, and left ventricular myocardial tissue in dogs with myxomatous mitral valve disease.
abstract: OBJECTIVE
  Altered serotonin (5-hydroxytryptamine, 5HT) signaling is postulated in development and progression of canine myxomatous mitral valve disease (MMVD). Little is known regarding platelet, plasma, valvular, or myocardial 5HT concentration ([5HT]) in affected dogs. We quantified [5HT] in platelet-rich plasma (PRP), platelet-poor plasma (PPP), mitral valve leaflets (MV), and left ventricular myocardium (LV).
  
  
  METHODS
  Forty-five dogs comprised 4 plasma groups of Cavalier King Charles Spaniels (CKCS) or non-CKCS, either healthy (CON) or MMVD affected: CKCS CON (n = 12); non-CKCS CON (n = 8); CKCS MMVD (n = 14); non-CKCS MMVD (n = 11). Twenty-four dogs comprised 3 tissue groups: MMVD (n = 8); other-HD (heart disease) (n = 7); non-HD, extracardiac disease (n = 9).
  
  
  METHODS
  High-performance liquid chromatography measured PRP, PPP, MV, and LV [5HT].
  
  
  RESULTS
  Platelet-rich plasma platelet [5HT] was greater in CKCS CON (1.83 femtograms/platelet [fg/plt]; range, 0.20-4.76; P = .002), CKCS MMVD (1.58 fg/plt; range, 0.70-4.03; P = .005), and non-CKCS MMVD (1.72 fg/plt; range, 0.85-4.44; P = .003) versus non-CKCS CON (0.92 fg/plt; range, 0.63-1.30). There was no group difference in PPP [5HT]. MV [5HT] was significantly higher in MMVD (32.4 ng/mg; range, 8.4-106.7) versus non-HD (3.6 ng/mg; range, 0-28.3; P = .01) and LV [5HT] was significantly higher in MMVD (11.9 ng/mg; range, 4.0-104.8) versus other-HD (0.9 ng/mg; range, 0-10.1; P = .011) and non-HD (2.5 ng/mg; range, 0-6.9; P = .001).
  
  
  CONCLUSIONS
  Platelet [5HT] was highest in healthy CKCS and both MMVD groups, but plasma [5HT] showed no group differences. Tissue [5HT] was highest in MV and LV of MMVD-affected dogs, suggesting altered 5HT signaling as a potential feature of MMVD. Interactions of platelet, valvular, and myocardial 5HT signaling warrant further investigation.
authors.affiliation: Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: S E
authors.initials: SE
authors.lastname: Cremer
authors.forename: G E
authors.initials: GE
authors.lastname: Singletary
authors.forename: L H
authors.initials: LH
authors.lastname: Olsen
authors.forename: K
authors.initials: K
authors.lastname: Wallace
authors.forename: J
authors.initials: J
authors.lastname: Häggström
authors.forename: I
authors.initials: I
authors.lastname: Ljungvall
authors.forename: K
authors.initials: K
authors.lastname: Höglund
authors.forename: C A
authors.initials: CA
authors.lastname: Reynolds
authors.forename: N
authors.initials: N
authors.lastname: Pizzinat
authors.forename: M A
authors.initials: MA
authors.lastname: Oyama
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000737:chemistry; D004283:Dog Diseases / Q000097:blood* / Q000378:metabolism; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D005260:Female; D006349:Heart Valve Diseases / Q000097:blood / Q000378:metabolism / Q000662:veterinary*; D006352:Heart Ventricles / Q000737:chemistry*; D008297:Male; D008943:Mitral Valve / Q000737:chemistry*; D010976:Platelet Count / Q000662:veterinary; D012701:Serotonin / Q000032:analysis* / Q000097:blood
chemical_list: D012701:Serotonin
keywords: 5-Hydroxytryptamine; Cavalier King Charles Spaniels; Heart disease; Myxomatous mitral valve disease