title: Augmentation of endogenous dopamine production increases lung liquid clearance.
abstract: We have previously reported that dopamine increased active Na+ transport in rat lungs by upregulating the alveolar epithelial Na,K-ATPase. Here we tested whether alveolar epithelial cells produce dopamine and whether increasing endogenous dopamine production by feeding rats a 4% tyrosine diet (TSD) would increase lung liquid clearance. Alveolar Type II cells express the enzyme aromatic-L-amino acid decarboxylase (AADC) and, when incubated with the dopamine precursor, 3-hydroxy-L-tyrosine (L-dopa), produce dopamine. Rats fed TSD, a precursor of L-dopa and dopamine, had increased urinary dopamine levels, which were inhibited by benserazide, an inhibitor of AADC. Rats fed TSD for 15, 24, and 48 hours had a 26, 46, and 45% increase in lung liquid clearance, respectively, as compared with controls. Also, dopaminergic D1 receptor antagonist--but not dopaminergic D2 receptor antagonist--inhibited the TSD-mediated increase in lung liquid clearance. Alveolar Type II cells isolated from the lungs of rats after they had been fed TSD for 24 hours demonstrated increased protein abundance of Na,K-ATPase alpha1 and beta1 subunits. Basolateral membranes isolated from peripheral lung tissue of tyrosine-fed rats had increased Na,K-ATPase activity and Na,K-ATPase alpha1 subunit. These data provide the first evidence that alveolar epithelial cells produce dopamine and that increasing endogenous dopamine increases lung liquid clearance.
authors.affiliation: Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611-3010, USA.
authors.forename: Yochai
authors.initials: Y
authors.lastname: Adir
authors.forename: Zaher S
authors.initials: ZS
authors.lastname: Azzam
authors.forename: Emilia
authors.initials: E
authors.lastname: Lecuona
authors.forename: Sergio
authors.initials: S
authors.lastname: Leal
authors.forename: Liuska
authors.initials: L
authors.lastname: Pesce
authors.forename: Vidas
authors.initials: V
authors.lastname: Dumasius
authors.forename: Alejandro M
authors.initials: AM
authors.lastname: Bertorello
authors.forename: Phillip
authors.initials: P
authors.lastname: Factor
authors.forename: James B
authors.initials: JB
authors.lastname: Young
authors.forename: Karen M
authors.initials: KM
authors.lastname: Ridge
authors.forename: Jacob Iasha
authors.initials: JI
authors.lastname: Sznajder
mesh_terms: D000818:Animals; D004298:Dopamine / Q000096:biosynthesis*; D004847:Epithelial Cells / Q000201:enzymology*; D015633:Extravascular Lung Water / Q000201:enzymology; D005527:Food, Fortified; D008297:Male; D011650:Pulmonary Alveoli / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014443:Tyrosine / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D014443:Tyrosine; D000254:Sodium-Potassium-Exchanging ATPase; D004298:Dopamine