Intermediate conductance potassium (IK) channels occur in human enteric neurons.
IK channels, which had been previously found in hemopoetically derived cells (including erythrocytes and lymphocytes) and epithelial cells, where they regulate proliferation, cell volume regulation and secretion, have only recently been discovered in neurons, where they had previously been claimed not to occur. Based on immunohistochemical detection of IK channel-like immunoreactivity, it has been reported that IK channel expression in enteric neurons is suppressed in Crohn's disease. In the present work we have investigated whether authentic IK channels are expressed by enteric neurons. Human and mouse tissue was investigated by immunohistochemistry, Western blot and RT-PCR. Immunohistochemical studies revealed IK channel-like immunoreactivity in large myenteric neurons, but not in other cell types in the external muscle layers. Many of these nerve cells had calbindin immunoreactivity. Western blots from the external muscle revealed an immunoreactive band at the molecular weight of the IK channel. Using RT-PCR, we detected a transcript corresponding to the IK channel gene in extracts from the ganglion containing layer. The sequence obtained from the RT-PCR product was identical to that previously published for the IK channel. We conclude that IK channels are expressed by human enteric neurons, including large smooth surfaced neurons that are possibly the human equivalent of the Dogiel type II neurons that express these channels in small mammals.
Furness
John B
JB
Department of Anatomy and Cell Biology and Centre for Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia. j.furness@unimelb.edu.au
Kearney
Kate
K
Robbins
Heather L
HL
Hunne
Billie
B
Selmer
Inger-Sofie
IS
Neylon
Craig B
CB
Chen
Mao Xiang
MX
Tjandra
Joe J
JJ
D000328:Adult; D000368:Aged; D000818:Animals; D015153:Blotting, Western; D064026:Calbindins; D017615:Enteric Nervous System / Q000166:cytology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D008875:Middle Aged; D009197:Myenteric Plexus / Q000166:cytology; D009474:Neurons / Q000145:classification / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D064030:S100 Calcium Binding Protein G / Q000378:metabolism
D064026:Calbindins; D015221:Potassium Channels; D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G