We previously reported that lung edema clearance was stimulated by dopamine (DA). The purpose of this study was to determine whether the DA-mediated stimulation of edema clearance occurs via an adrenergic or dopaminergic regulation of alveolar epithelial Na, K-ATPase. When isolated perfused rat lungs were coinstilled with DA and SCH 23390 (a specific D(1) receptor antagonist), there was a dose-dependent attenuation of the stimulatory effects of DA. Coinstillation with S-sulpiride (a specific D(2) receptor antagonist) or propranolol (a beta-adrenergic antagonist) did not alter DA-stimulated clearance. Similarly, the specific dopaminergic D(1) agonist fenoldopam increased lung edema clearance, but quinpirole (a specific dopaminergic D(2) agonist) did not. (125)I-SCH 23982 binding studies suggested that D(1) receptors are expressed on alveolar type II (ATII) cells with an apparent dissociation constant (K(d)) of 4.4 nM and binding maximum (Bmax) 9.8 pmol/mg. Consistent with these results, the D(1) receptor messenger RNA (mRNA) and protein were detected in ATII cells by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. These data demonstrate a novel mechanism involving the activation of dopaminergic D(1) receptors which mediates DA-stimulated edema removal from rat lungs.

beta-Adrenergic agonists have been reported to increase lung liquid clearance by stimulating active Na+ transport across the alveolar epithelium. We studied mechanisms by which beta-adrenergic isoproterenol (Iso) increases lung liquid clearance in isolated perfused fluid-filled rat lungs. Iso perfused through the pulmonary circulation at concentrations of 10(-4) to 10(-8) M increased lung liquid clearance compared with that of control lungs (P < 0.01). The increase in lung liquid clearance was inhibited by the beta-antagonist propranolol (10(-5) M), the Na(+)-channel blocker amiloride (10(-4) M), and the antagonist of Na-K-ATPase, ouabain (5 x 10(-4) M). Colchicine, which inhibits cell microtubular transport of ion-transporting proteins to the plasma membrane, blocked the stimulatory effects of Iso on active Na+ transport, whereas the isomer lumicolchicine, which does not affect cell microtubular transport, did not inhibit Na+ transport. In parallel with these changes, the Na-K-ATPase alpha 1-subunit protein abundance and activity increased in alveolar type II cells stimulated by 10(-6) M Iso. Colchicine blocked the stimulatory effect of Iso and the recruitment of Na-K-ATPase alpha 1-protein to the basolateral membrane of alveolar type II cells. Accordingly, Iso increased active Na+ transport and lung liquid clearance by stimulation of beta-adrenergic receptors and probably by upregulation of apical Na+ channels and basolateral Na-K-ATPase mechanisms. Recruitment from intracellular pools and microtubular transport of Na+ pumps to the plasma membrane participate in beta-adrenergic stimulation of lung liquid clearance in rat lungs.

Annals of the New York Academy of SciencesVolume 834, Issue 1 p. 651-652 Alpha-2 Na,K-ATPase Contributes to Lung Liquid Clearancea K. RIDGE, K. RIDGE Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorW. OLIVERA, W. OLIVERA Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorD. H. RUTSCHMAN, D. H. RUTSCHMAN Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorR. W. MERCER, R. W. MERCER Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorB. UHAL, B. UHAL Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorS. HOROWITZ, S. HOROWITZ Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorF. HUGHES, F. HUGHES Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorP. FACTOR, P. FACTOR Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorM. L. BARNARD, M. L. BARNARD Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorJ. I. SZNAJDER, Corresponding Author J. I. SZNAJDER Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Address for correspondence: Jacob Iasha Sznajder, MD, Pulmonary and Critical Care Medicine, Michael Reese Hospital, 2929 S. Ellis, RC-216, Chicago, IL 60616 (tel: 312-791-5776; fax: 312-791-2349.Search for more papers by this author K. RIDGE, K. RIDGE Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorW. OLIVERA, W. OLIVERA Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorD. H. RUTSCHMAN, D. H. RUTSCHMAN Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorR. W. MERCER, R. W. MERCER Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorB. UHAL, B. UHAL Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorS. HOROWITZ, S. HOROWITZ Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorF. HUGHES, F. HUGHES Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorP. FACTOR, P. FACTOR Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorM. L. BARNARD, M. L. BARNARD Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Search for more papers by this authorJ. I. SZNAJDER, Corresponding Author J. I. SZNAJDER Pulmonary and Critical Care Medicine Division Michael Reese Hospital and University of Illinois Chicago, Illinois 60680; Winthrop Hospital New York, New York 11501; Washington University St. Louis, Missouri 63110; Rush Presbyterian-St. Luke's Medical Center and Northeastern Illinois University Chicago, Illinois 60637Address for correspondence: Jacob Iasha Sznajder, MD, Pulmonary and Critical Care Medicine, Michael Reese Hospital, 2929 S. Ellis, RC-216, Chicago, IL 60616 (tel: 312-791-5776; fax: 312-791-2349.Search for more papers by this author First published: 17 December 2006 https://doi.org/10.1111/j.1749-6632.1997.tb52340.xCitations: 7 a This work was supported by HL-48129, the American Lung Association, and Michael Reese Hospital. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCES 1 Olivera, W., K. Ridge, L. D. H. Wood & J. I. Sznajder. 1994. Active sodium transport and alveolar epithelial Na,K-ATPase increase during subacute hyperoxia in rats. Am. J. Physiol. 266: L577–L584. 2 Matthay, M. A. & J. P. Wiener-Kronish. 1990. Intact epithelial barrier function is critical for the resolution of alveolar edema in humans. Am. Rev. Respir. Dis. 142: 1250–1257. 3 Sznajder, J. I., W. G. Olivera, K. M. Ridge & D. H. Rutschman. 1995. Mechanisms of lung liquid clearance during hyperoxia in isolated rat lungs. Am. J. Respir. Crit. Med. 151: 1519–1525. 4 Schneeberger, E. E. & K. M. McCarthy. 1986. Cytochemical localization of Na+-K+-ATPase in rat type II pneumocytes. J. Appl. Physiol. 60: 1584–1589. 5 Suzuki, S., D. Zuege & Y. Berthiaume. 1995. Sodium-independent modulation of Na,K-ATPase activity by β-adrenergic agonist in alveolar type II cells. Am. J. Physiol. 268: L983–L990. 6 Shyjan, A. W. & R. Levenson. 1989. Antisera specific for the α1, α2, α3, and β subunits in rat tissue membranes. Biochemistry 28: 4531–4535. 7 Orlowski, J. & J. B. Lingrel. 1988. Tissue specific and developmental regulation of rat Na,K-ATPase catalytic α and β subunit mRNAs. J. Biol. Chem. 263: 10436–10442. 8 Adamson, I. Y. R. & D. H. Bowden. 1974. The type 2 cell as progenitor of alveolar epithelial regeneration. Lab. Invest. 30: 35–42. Citing Literature Volume834, Issue1Na/K‐ATPase and Related Transport ATPases: Structure, Mechanism, and RegulationNovember 1997Pages 651-652 ReferencesRelatedInformation

Pulmonary edema clearance is driven primarily by active sodium transport out of the alveoli, mediated predominantly by apical sodium channels and the basolateral NA,K-ATPase. We postulated that dopamine, analogous to its effects in other transporting epithelia, could regulate these sodium transport mechanisms and affect lung liquid clearance. We therefore studied the effects of dopamine on sodium transport and liquid clearance in isolated perfused rat lungs. Instillation of dopamine into the airways caused a dose-dependent increase in liquid clearance from isolated rat lungs of up to 33% above control values at 10(-8) to 10(-4) M concentrations. 10(-6) M amiloride, which selectively inhibits apical sodium channels, decreased basal liquid clearance by 34% but did not inhibit the dopamine-mediated stimulation of lung liquid clearance. Instillation of 10(-4) M amiloride into rat airways, which inhibits other sodium transport mechanisms non-selectively, decreased basal lung liquid clearance by 49% and inhibited the dopamine-mediated stimulation of lung liquid clearance. Perfusion of rat lungs with 5 x 10(-4) M ouabain to specifically inhibit Na,K-ATPase reduced both basal clearance (by 55%) and the dopamine-stimulated increase in lung fluid clearance. Conceivably, the stimulation of lung liquid clearance by dopamine is due to a modulation of Na,K-ATPase in the pulmonary epithelium.

We quantitated the ability of intratracheally administered liposome-encapsulated antioxidant enzymes to reduce reactive oxygen species injury to the pulmonary microvasculature. Cationic liposomes containing 3,500 U of Cu,Zn superoxide dismutase (Cu,Zn SOD) and 3,124 U of catalase were instilled into rabbits. The animals were killed 2-72 h later and their lungs were removed and perfused with Krebs Ringer with 5% wt/vol of fat-free bovine serum albumin. The pulmonary filtration co-efficient (Kf,c) was measured before and after adding 500 microM xanthine and 5 mU/ml xanthine oxidase (XO) into the lung perfusate. Two hours after a single intratracheal instillation of liposome-entrapped Cu,Zn SOD and catalase, lung antioxidant enzyme activities were 34 and 125% higher than the corresponding control values, remained virtually unchanged for up to 8 h post-instillation, and then decreased, reaching baseline values between 24 and 72 h. Addition of xanthine and XO into the lung perfusate of un-instilled rabbits, or rabbits that received liposomes with inactivated enzymes, caused a 100% increase in Kf,c (control value: 2 +/- 0.12 ml.min-1 x cmH2O-1 per 100 g dry lung weight). On the other hand, Kf,c values of rabbits lungs instilled with liposome-encapsulated active Cu,Zn SOD and catalase and challenged with xanthine and XO 8-24 h later remained at baseline levels. Instillation of liposomes containing either enzyme was equally effective in preventing the increase in Kf,c, indicating that both superoxide anions and hydrogen peroxide were necessary for the initiation of injury. We concluded that intratracheal instillation of liposome-encapsulated antioxidant enzymes caused a transient increase of lung antioxidant enzyme levels which protects the pulmonary microvasculature from free radical-initiated injury.

We investigated the effect of xanthine (X) plus xanthine oxidase (XO) on pulmonary microvascular endothelial permeability in isolated rabbit lungs perfused with Krebs buffer containing bovine serum albumin (5 g/100 ml). Addition of five mU/ml XO and 500 microM X to the perfusate caused a twofold increase in the pulmonary capillary filtration coefficient (Kf,c) 30 min later without increasing the pulmonary capillary pressure. This increase was prevented by allopurinol or catalase but not by superoxide dismutase or dimethyl sulfoxide. Because these data implicated hydrogen peroxide (H2O2) as the injurious agent, we measured its concentration in the perfusate after the addition of X and XO for a 60-min interval. In the absence of lung tissue and albumin, H2O2 increased with time, reaching a concentration of approximately 250 microM by 60 min. If albumin (5 g/100 ml) was added to the perfusate, or in the presence of lung tissue, the corresponding values were 100 microM and less than 10 microM, respectively. To understand the mechanisms of H2O2 scavenging by lung tissue, we added a 250 microM bolus of H2O2 to the lung perfusate. We found that H2O2 was removed rapidly, with a half-life of 0.31 +/- 0.04 (SE) min. This variable was not increased significantly by inhibition of lung catalase activity with sodium azide or inhibition of the lung glutathione redox cycle with 1-chloro-2,4-dinitrobenzene. However, inhibition of both enzymatic systems increased the half-life of H2O2 removal to 0.71 +/- 0.09 (SE) min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)