Linked Life Data

9594022

Source:http://linkedlifedata.com/resource/pubmed/id/9594022

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-7-17
pubmed:abstractText
It has previously been shown in studies of a renal epithelial cell line that nonselective cation (NSC) channels are activated by exposure to hypertonic solution. We have also found such channels in excised patches of colonic crypt cells. They require high Ca2+ activities on the cytosolic side and a low ATP concentration for their activation and have not been recorded from cell-attached patches of colonic crypts. We examine here whether this type of channel is activated by hypertonic cell shrinkage. Bath osmolality was increased by addition of 25, 50 or 100 mmol/l mannitol. Cell-attached and whole-cell patch recordings were obtained from rat base and mid-crypt cells. In whole-cell recordings we found that addition of 50 or 100 mmol/l mannitol depolarized these cells significantly from -78+/-2.0 to -66+/-3.8 mV (n=22) and from -78+/-1. 3 to -56+/-2.6 mV (n=61), respectively, and reduced the whole-cell conductance from 20+/-8.0 to 14+/-6.6 nS (n=7) and from 20+/-3.0 to 9.8+/-1.6 nS (n=19), respectively. In cell-attached patches K+ channels with a single-channel conductance of approximately 16 pS were found in most recordings. The activity of these channels (NxPo, N=number, Po=open channel probability) was reduced from 2.08+/-0.37 to 0.98+/-0.23 (n=15) by the addition of 50 mmol/l mannitol and from 1.75+/-0.26 to 0.77+/-0.20 (n=12) by 100 mmol/l mannitol. No NSC channel activity was apparent in any of these recordings. Previously we have shown that the 16-pS K+ channel is controlled by cytosolic Ca2+ ([Ca2+]i). Therefore we measured [Ca2+]i by the fura-2 method and found that hypertonic solution reduced [Ca2+]i significantly (n=16). These data indicate that exposure of rat colonic crypts to hypertonic solutions does not activate NSC channels; [Ca2+]i falls in hypertonic solution leading to a reduction in the value of K+ channel NxPo, a reduced whole-cell conductance and depolarization of mid-crypt cells. These processes probably assist volume regulation inasmuch as they reduce KCl losses from the cell.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0031-6768
pubmed:author
pubmed:issnType
Print
pubmed:volume
436
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
227-32
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Hypertonic cell shrinkage reduces the K+ conductance of rat colonic crypts.
pubmed:affiliation
Physiologisches Institut der Albert-Ludwigs-Universität, Hermann-Herder-Strasse 7, D-79104 Freiburg i. Br., Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't