Linked Life Data

14576089

Source:http://linkedlifedata.com/resource/pubmed/id/14576089

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2004-1-6
pubmed:abstractText
Surface cells of the mammalian distal colon are shown to molecularly express the amiloride-sensitive epithelial Na+ channel composed of three homologous subunits (alpha-, beta-, and gamma-ENaC). However, because basic electrophysiological properties of amiloride-sensitive Na+ channels expressed in these cells are largely unknown at the cellular level, functional evidence for the involvement of the subunits in the native channels is incomplete. Using electrophysiological techniques, we have now characterized functional properties of native ENaC in surface cells of rectal colon (RC) of rats fed a normal Na+ diet. Ussing chamber experiments showed that apical amiloride inhibited a basal short-circuit current in mucosal preparation of RC with an apparent half-inhibition constant (Ki) value of 0.20 microM. RT-PCR analysis confirmed the presence of transcripts of alpha-, beta-, and gamma-rENaC in rectal mucosa. Whole cell patch-clamp experiments in surface cells of intact crypts acutely isolated from rectal mucosa identified an inward cationic current, which was inhibited by amiloride with a Ki value of 0.12 microM at a membrane potential of -64 mV, the inhibition being weakly voltage dependent. Conductance ratios of the currents were Li+ (1.8) > Na+ (1) >> K+ ( approximately 0), respectively. Amiloride-sensitive current amplitude was almost the same at 15 or 150 mM extracellular Na+, suggesting a high Na+ affinity for current activation. These results are consistent with the hypothesis that a heterooligomer composed of alpha-, beta-, and gamma-ENaC may be the molecular basis of the native channels, which are responsible for amiloride-sensitive electrogenic Na+ absorption in rat rectal colon.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0363-6143
pubmed:author
pubmed:issnType
Print
pubmed:volume
286
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
C380-90
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Amiloride-sensitive epithelial Na+ channel currents in surface cells of rat rectal colon.
pubmed:affiliation
Laboratory of Physiology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't