Nasal Potential Difference Measurements to Assess CFTR Ion Channel Activity
The Nasal potential difference measurement is used to measure the voltage across the nasal epithelium, which results from transepithelial ion transport and reflects in part CFTR function. The electrophysiologic abnormality in cystic fibrosis was first described 30 years ago and correlates with features of the CF phenotype. NPD measurement is an important in vivo research and diagnostic tool, and is used to assess the efficacy of new treatments such as gene therapy and ion transport modulators. This chapter will elaborate on the electrophysiological principles behind the test, the equipment required, the methods, and the analysis of the data.
Key wordsNasal potential difference CFTR, ENaC amiloride cAMP isoproterenol electrodes ion transport
The authors are grateful to Michael Knowles for providing a critical review of the material presented and also to Peter Durie for helpful critiques in devising current methods proposed here. Support for this work was provided by the US National Institute of Health grants 1K23DK075788-01 and 1R03DK084110-01 (to S.M.R.), 1P30DK072482-01A1 (to Eric J. Sorscher for infrastructural support) and Cystic Fibrosis Foundation grants CLANCY05Y2 (S.M.R. and J.P.C.). This project was supported in part by grants from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Heart, Lung, and Blood Institute. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Diabetes and Digestive and Kidney Diseases; National Heart, Lung, and Blood Institute; or the National Institutes of Health.
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