Staff Physician, Medical Service, SFVAMC
Assistant Professor of Medicine In Residence, UCSF

Email: meshell.johnson@va.gov

The main function of the lung is gas exchange. Millions of tiny air sacs, called alveoli, take in oxygen and release carbon dioxide. Certain diseases, such as pulmonary edema or acute respiratory distress syndrome, interfere with the lung's ability to regulate fluid transport and as a result, the alveoli become flooded, causing impairment of gas exchange. A better understanding of how the lung regulates fluid balance will help develop ways to prevent or treat this distress. Dr. Johnson's research focuses on the study of ion (electrically charged atom) and fluid transport in the lung, with an emphasis on ion transport in alveolar type I cells, which cover the vast majority of the internal surface area of the lung. Her work has demonstrated that type I cells transport ions and contain the molecular machinery for active ion transport. Because it was previously thought that type I cells were inert cells that only performed a barrier function in the lung and allowed the passive transport of water, her findings altered the previous paradigms of ion and fluid transport in the lung. Her research continues to focus on understanding the mechanisms of ion and fluid transport in the lung.

Johnson M, Bao H, Helms M, Chen X, Tigue Z, Jain L, Dobbs L, Eaton D. 2006. Functional ion channels in pulmonary alveolar type I cells support a role for type I cells in lung ion transport. Proc Natl Acad Sci USA 103(13):4964-9.

Johnson MD. 2007. Ion transport in alveolar type I cells. Mol Biosyst 3:178-86.