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This Article Full Text Full Text (PDF) All Versions of this Article: 297/1/L153    most recent 90524.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Han, K.-H. Articles by Weiner, I. D. PubMed PubMed Citation Articles by Han, K.-H. Articles by Weiner, I. D.

Expression of the gas-transporting proteins, Rh B glycoprotein and Rh C glycoprotein, in the murine lung

¹Department of Anatomy, Ewha Womans University, Seoul, Republic of Korea; ²Division of Nephrology, Hypertension, and Transplantation, University of Florida College of Medicine, Gainesville, Florida; ³Division of Nephrology, Chungbuk National University College of Medicine, Cheongju, Republic of Korea; and ⁴Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida

Submitted 15 October 2008 ; accepted in final form 4 May 2009

A family of gas-transporting proteins, the Mep/Amt/Rh glycoprotein family, has been identified recently. These are integral membrane proteins, are widely expressed in sites of gas transport, and are known to transport the gaseous molecule, NH₃, and recent evidence indicates they can transport CO₂. Because the mammalian lung is a critical site for gas transport, the current studies examine the expression of the nonerythroid members of this extended family, Rh B glycoprotein (Rhbg) and Rh C glycoprotein (Rhcg), in the normal mouse lung. Real-time RT-PCR and immunoblot analysis demonstrated both Rhbg and Rhcg mRNA and protein expression, respectively. Immunohistochemistry demonstrated both Rhbg and Rhcg were expressed in bronchial and bronchiolar epithelial cells. Rhbg was expressed by Clara cells, specifically, whereas all bronchial/bronchiolar epithelial cells, with the exception of goblet cells, expressed Rhcg. Rhbg expression was basolateral, whereas Rhcg exhibited apical and intracellular immunolabel, polarized expression similar to that observed in Rhbg- and Rhcg-expressing epithelial cells in other organs. There was no detectable expression of either Rhbg or Rhcg in alveolar endothelial or epithelial cells, in pneumocytes or in vascular tissue. In vitro studies using cultured bronchial epithelial cells confirm Rhbg and Rhcg expression, demonstrate that saturable, not diffusive, transport is the primary mechanism of ammonia/methylammonia transport, and show that the saturable transport mechanism has kinetics similar to those demonstrated previously for Rhbg and Rhcg. These findings suggest Rhbg and Rhcg may contribute to bronchial epithelial cell ammonia metabolism and suggest that they do not contribute to pulmonary CO₂ transport.

ammonia; CO₂; transport