title: Apelin: a new plasma marker of cardiopulmonary disease.
abstract: OBJECTIVE
  Dyspnea is a major symptom of both parenchymal lung disease and chronic heart failure. Underlying cardiac dysfunction can be assessed by measurement of cardiac-derived B-type natriuretic peptide or its precursor in plasma. However, no specific endocrine marker of the lung parenchyma has so far been identified. We therefore examined whether plasma concentrations of apelin, a novel inotropic hormone, is affected in patients with chronic parenchymal lung disease without cardiac dysfunction.
  
  
  RESULTS
  Patients with severe chronic parenchymal lung disease and normal cardiac function (n=53), idiopathic pulmonary hypertension with increased right ventricular pressure (n=10), and patients with severe left ventricular systolic dysfunction (n=22) were enrolled. Plasma apelin-36 and proBNP concentrations were measured with radioimmunoassays. While proBNP plasma concentrations were unaffected in chronic parenchymal lung disease patients compared to normal subjects, the apelin-36 concentration was reduced 3.3-fold (median 35 pmol/l (0-162 pmol/l) vs. 117 pmol/l (55-232 pmol/l), P<0.001). Moreover, the apelin-36 concentration was decreased in chronic heart failure patients (2.1-fold, P<0.01) and in patients with idiopathic pulmonary hypertension (4.0-fold, P<0.001). In contrast, the proBNP concentration was highly increased in both chronic heart failure and idiopathic pulmonary hypertension patients.
  
  
  CONCLUSIONS
  Plasma concentrations of apelin-36, a novel inotropic peptide, are decreased in patients with chronic parenchymal lung disease and preserved cardiac function. Combined measurement of apelin-36 and proBNP may be a new diagnostic approach in distinguishing pulmonary from cardiovascular causes of dyspnea.
authors.affiliation: Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, 9 Blegdamsvej, DK-2100, Copenhagen, Denmark. jpg@dadlnet.dk
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Goetze
authors.forename: Jens F
authors.initials: JF
authors.lastname: Rehfeld
authors.forename: Jørn
authors.initials: J
authors.lastname: Carlsen
authors.forename: Regitze
authors.initials: R
authors.lastname: Videbaek
authors.forename: Claus B
authors.initials: CB
authors.lastname: Andersen
authors.forename: Soeren
authors.initials: S
authors.lastname: Boesgaard
authors.forename: Lennart
authors.initials: L
authors.lastname: Friis-Hansen
mesh_terms: D000368:Aged; D000073861:Apelin; D015415:Biomarkers / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood* / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D011660:Pulmonary Heart Disease / Q000097:blood / Q000175:diagnosis*
chemical_list: C115436:APLN protein, human; D000073861:Apelin; D015415:Biomarkers; D036341:Intercellular Signaling Peptides and Proteins