Potassium channels in colonic crypts.
A characteristic feature of intestinal epithelia is their ability to secrete chloride (Cl-), a process that occurs mainly in intestinal crypts and is the critical transport event in secretory diarrhoea. Increased potassium (K+) channel activity in the basolateral membrane has an important role in the Cl- secretory process by hyperpolarising the cell and maintaining a favourable electrochemical driving force for Cl- exit at the apical membrane. We have shown, using patch-clamp techniques, that the basolateral membrane of human colonic crypt cells contains low conductance K+ channels that are voltage and calcium (Ca2+) sensitive and blocked by barium (Ba2+). These K+ channels are regulated by cytosolic cyclic adenosine monophosphate (cAMP) and Ca2+, intracellular second messengers that also stimulate Cl- secretion. This population of human intestinal K+ channels may be a target for the pharmacological control of Cl- secretory diarrhoea.
Sandle
G I
GI
Department of Medicine, Hope Hospital (University of Manchester, School of Medicine, Salford, UK.
McNicholas
C M
CM
Lomax
R B
RB
D003994:Bucladesine / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D002712:Chlorides / Q000502:physiology; D003106:Colon / Q000166:cytology / Q000502:physiology; D003967:Diarrhea / Q000209:etiology*; D004594:Electrophysiology; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism / Q000502:physiology*; D017136:Ion Transport / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*
D015220:Calcium Channels; D002712:Chlorides; D015221:Potassium Channels; D003994:Bucladesine; D002217:Carbachol