Polarized epithelium and localization of ion channels
Well, that's a first for me. I wouldn't have guessed gut cells would have voltage-gated channels.
This article describes voltage-gated sodium channels on both the luminal and basolateral membranes: 

Barshack, I., Levite, M., Lang, A., Fudim, E., Picard, O., Ben Horin, S., &amp; Chowers, Y. (2008). Functional voltage-gated sodium channels are expressed in human intestinal epithelial cells. Digestion, 77(2), 108-117.
http://www.ncbi.nlm.nih.gov/pubmed/18391489