Letter: Measurement of electrical potential difference across colonic mucosa in cystic fibrosis patients.

By measuring potential difference between rectal mucosa and perianal skin using a 
reference electrode placed on the forearm, we demonstrated an altered potential 
difference in cystic children compared with control adults and normal children. 
We suggested this might be due to an alteration in the 
rectal mucosa potential or altered skin potential, or both, in cystic 
fibrosis. We measured skin and rectal charges directly by connecting our 
reference electrode to the blood stream through an intravenous line. Using 
this technique we showed that the cystic fibrosis patients (C.F.) have 
an abnormal perianal skin potential difference compared with readings we obtained 
in normal children. There was little difference in the transmural rectal 
potential difference between our cystic patients and previously reported values in 
normal adults. Thus the recent paper confirms our findings of normal 
polarity of the rectal mucosa surface and the increased skin polarisation 
in cystic fibrosis. 