title: Melatonin administration acutely decreases the diffusing capacity of carbon monoxide in human lungs.
abstract: BACKGROUND
  Most physiological measurements of the pulmonary diffusing capacity use carbon monoxide (CO) as a tracer gas. Similar to CO, melatonin binds the hemoglobin in the blood.
  
  
  OBJECTIVE
  The present study was designed to assess the effect of exogenous melatonin administration on pulmonary functions including diffusing capacity for carbon monoxide (DL(CO)) in healthy subjects.
  
  
  METHODS
  The study was performed in a randomized, double-blind, placebo-controlled manner. DL(CO) was measured in 22 healthy male volunteers (age 18-25 years) who were randomized to melatonin (n = 11) and placebo administration (n = 11). At baseline, DL(CO), alveolar volume (V(A)) and other spirometric parameters such as forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), peak expiratory flow (PEF) and maximal voluntary ventilation (MVV) were measured. DL(CO) was then corrected for the hemoglobin concentration. Measurements were repeated in a double-blind fashion 60 min after the administration of melatonin (1 mg) or placebo.
  
  
  RESULTS
  DL(CO) was significantly decreased (39.31 +/- 4.75 vs. 34.82 +/- 6.18 ml/min/mm Hg) 60 min after the melatonin administration (p = 0.01), while FEV(1), FVC, FEV(1)/FVC, PEF and MVV values did not demonstrate significant differences. Placebo administration did not result in significant alteration in any of these parameters.
  
  
  CONCLUSIONS
  In healthy subjects, oral administration of melatonin acutely influences the DL(CO) without affecting other pulmonary function test results. We conclude that melatonin may have a reducing effect on the DL(CO) in the lungs.
authors.affiliation: Department of Physiology, Trakya University, School of Medicine, Edirne, Turkey. arzuvardar22@hotmail.com
authors.forename: Selma Arzu
authors.initials: SA
authors.lastname: Vardar
authors.forename: Gülay Durmus
authors.initials: GD
authors.lastname: Altun
authors.forename: Caner
authors.initials: C
authors.lastname: Günerbuyuk
authors.forename: Osman Nuri
authors.initials: ON
authors.lastname: Hatipoglu
authors.forename: Selva
authors.initials: S
authors.lastname: Mert
authors.forename: Kadir
authors.initials: K
authors.lastname: Kaymak
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D002248:Carbon Monoxide / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D005260:Female; D005541:Forced Expiratory Volume; D006339:Heart Rate; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008550:Melatonin / Q000627:therapeutic use*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000502:physiology; D012016:Reference Values; D012129:Respiratory Function Tests; D012727:Sex Characteristics
chemical_list: D002248:Carbon Monoxide; D008550:Melatonin