Linked Life Data

15292047

Source:http://linkedlifedata.com/resource/pubmed/id/15292047

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2004-11-3
pubmed:abstractText
In the medullary thick ascending limb (MTAL) of rat kidney, inhibiting basolateral Na(+)/H(+) exchange with either amiloride or nerve growth factor (NGF) results secondarily in inhibition of apical Na(+)/H(+) exchange, thereby decreasing transepithelial HCO(3)(-) absorption. To assess the possible role of the Na(+)/H(+) exchanger NHE1 in this regulatory process, MTALs from wild-type and NHE1 knockout (NHE1(-/-)) mice were studied using in vitro microperfusion. The rate of HCO(3)(-) absorption was decreased 60% in NHE1(-/-) MTALs (15.4 +/- 0.5 pmol.min(-1).mm(-1) wild-type vs. 6.0 +/- 0.5 pmol.min(-1).mm(-1) NHE1(-/-)). Transepithelial voltage, an index of the NaCl absorption rate, did not differ in wild-type and NHE1(-/-) MTALs. Basolateral addition of 10 microM amiloride or 0.7 nM NGF decreased HCO(3)(-) absorption by 45-49% in wild-type MTALs but had no effect on HCO(3)(-) absorption in NHE1(-/-) MTALs. Inhibition of HCO(3)(-) absorption by vasopressin and stimulation by hyposmolality, both of which regulate MTAL HCO(3)(-) absorption through primary effects on apical Na(+)/H(+) exchange, were similar in wild-type and NHE1(-/-) MTALs. Thus the regulatory defect in NHE1(-/-) MTALs is specific for factors (bath amiloride and NGF) shown previously to inhibit HCO(3)(-) absorption through primary effects on basolateral Na(+)/H(+) exchange. These findings demonstrate a novel role for NHE1 in transepithelial HCO(3)(-) absorption in the MTAL, in which basolateral NHE1 controls the activity of apical NHE3. Paradoxically, a reduction in NHE1-mediated H(+) extrusion across the basolateral membrane leads to a decrease in apical Na(+)/H(+) exchange activity that reduces HCO(3)(-) absorption.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1931-857X
pubmed:author
pubmed:issnType
Print
pubmed:volume
287
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
F1244-9
pubmed:dateRevised
2011-4-28
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Transepithelial HCO3- absorption is defective in renal thick ascending limbs from Na+/H+ exchanger NHE1 null mutant mice.
pubmed:affiliation
Department of Medicine, University of Texas Medical Branch, 301 Univ. Boulevard, Galveston, TX 77555, USA. dgood@utmb.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't