The regulation of epithelial cell cAMP- and calcium-dependent chloride channels.
This chapter has focused on two types of chloride conductance found in epithelial cells. The leap from the Ussing chamber to patch-clamp studies has identified yet other conductances present which have also been electrophysiologically characterized. In the case of the swelling activated wholecell chloride current, a physiological function is apparent and a single-channel basis found, but its genetic identity remains unknown (see reviews by Frizzell and Morris, 1994; and Strange et al., 1996). The outwardly rectified chloride channel has been the subject of considerable electrophysiological interest over the past 10 years and is well characterized at the single-channel level, but its physiological function remains controversial (reviewed by Frizzell and Morris, 1994; Devidas and Guggino, 1997). Yet other conductances related to the CLC gene family also appear to be present in epithelial cells of the kidney (reviewed by Jentsch, 1996; Jentsch and Gunter, 1997) where physiological functions for some isoforms are emerging. Clearly, there remain many unknowns. Chief among these is the molecular basis of GCa2+Cl and many of other the conductances. As sequences become available it is expected that the wealth of information gained by investigation into CFTR function will provide a conceptual blueprint for similar studies in these later channel clones.
Morris
A P
AP
Department of Integrative Biology, University of Texas-Houston Health Science Center 77030, USA.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000502:physiology; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology
C505032:CFTR protein, human; D018118:Chloride Channels; D002712:Chlorides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D011493:Protein Kinase C; D002118:Calcium