Linked Life Data

2831731

Source:http://linkedlifedata.com/resource/pubmed/id/2831731

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2 Pt 1
pubmed:dateCreated
1988-4-11
pubmed:abstractText
We have recently shown that substitution of Li+ for perfusate Na+ eliminates the HCO3(-)-rich choleresis produced by ursodeoxycholic acid (UDCA) in isolated perfused rat liver and that the increase in bile flow produced by both UDCA and taurocholic acid is partially inhibited by 1 mM amiloride. Although these findings are consistent with a role for Na+-H+ exchange in the choleresis produced by these bile acids, both Li+ substitution and amiloride affect other cellular processes, including Na+-K+-ATPase activity. We have now further explored both the relationship between UDCA-stimulated bile flow and biliary HCO3- secretion and the possible role of Na+-H+ exchange in this process by comparing the effects of amiloride with two of its more potent and presumably more specific analogues, 5-(N,N-dimethyl)amiloride hydrochloride (DMA) and 5-(N-ethyl-N-isopropyl)amiloride (EIA). In the absence of inhibitor, UDCA increased biliary HCO3- concentration ([HCO3-]) up to an apparent maximum of 60-70 mM, and bile flow and biliary HCO3- output appeared to be linearly related over a sixfold range of bile flow rates. Amiloride, DMA, and EIA each produced a concentration-dependent inhibition of UDCA-stimulated bile flow and biliary HCO3- output with an apparent rank order potency (EIA greater than DMA greater than amiloride) similar to that reported for inhibition of Na+-H+ exchange in other systems. None of the inhibitors significantly altered biliary UDCA output or the relationship between UDCA-induced bile flow and either biliary [HCO3-] or biliary HCO3- output. Effects of these inhibitors did not appear attributable either to nonspecific toxicity, as reflected by hepatic release of lactate dehydrogenase or K+, or to inhibition of hepatic Na+-K+-ATPase, measured as Na+-dependent uptake of 86Rb. In contrast to their effects on UDCA choleresis, these inhibitors had little or no effect on basal bile flow, biliary [HCO3-], and biliary HCO3- output. These findings indicate that UDCA-induced but not basal bile formation is closely coupled to biliary HCO3- concentration and output, and they provide additional evidence that UDCA choleresis requires an intact Na+-H+ exchange mechanism.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0002-9513
pubmed:author
pubmed:issnType
Print
pubmed:volume
254
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
G232-41
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Ursodeoxycholic acid choleresis: relationship to biliary HCO-3 and effects of Na+-H+ exchange inhibitors.
pubmed:affiliation
Department of Medicine, University of California School of Medicine, San Francisco 94143.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't