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Article: Involvement of the cystic fibrosis transmembrane conductance regulator in the acidosis-induced efflux of ATP from rat skeletal muscle

TitleInvolvement of the cystic fibrosis transmembrane conductance regulator in the acidosis-induced efflux of ATP from rat skeletal muscle
Authors
Issue Date2010
PublisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751
Citation
Journal Of Physiology, 2010, v. 588 n. 22, p. 4563-4578 How to Cite?
AbstractThe present study was performed to investigate the effect of acidosis on the efflux of ATP from skeletal muscle. Infusion of lactic acid to the perfused hindlimb muscles of anaesthetised rats produced dose-dependent decreases in pH and increases in the interstitial ATP of extensor digitorum longus (EDL) muscle: 10 mm lactic acid reduced the venous pH from 7.22 ± 0.04 to 6.97 ± 0.02 and increased interstitial ATP from 38 ± 8 to 67 ± 11 nm. The increase in interstitial ATP was well-correlated with the decrease in pH (r2= 0.93; P < 0.05). Blockade of cellular uptake of lactic acid using α-cyano-hydroxycinnamic acid abolished the lactic acid-induced ATP release, whilst infusion of sodium lactate failed to depress pH or increase interstitial ATP, suggesting that intracellular pH depression, rather than lactate, stimulated the ATP efflux. Incubation of cultured skeletal myoblasts with 10 mm lactic acid significantly increased the accumulation of ATP in the bathing medium from 0.46 ± 0.06 to 0.76 ± 0.08 μm, confirming the skeletal muscle cells as the source of the released ATP. Acidosis-induced ATP efflux from the perfused muscle was abolished by CFTRinh-172, a specific inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR), or glibenclamide, an inhibitor of both KATP channels and CFTR, but it was not affected by atractyloside, an inhibitor of the mitochondrial ATP transporter. Silencing of the CFTR gene using an siRNA abolished the acidosis-induced increase in ATP release from cultured myoblasts. CFTR expression on skeletal muscle cells was confirmed using immunostaining in the intact muscle and Western blotting in the cultured cells. These data suggest that depression of the intracellular pH of skeletal muscle cells stimulates ATP efflux, and that CFTR plays an important role in the release mechanism. It is known that exercise reduces the pH of muscle, and also stimulates the release of ATP from muscle cells. This ATP is converted to adenosine in the extracellular space; adenosine relaxes blood vessels, which helps to increase the blood flow to the exercising muscle. The mechanism of ATP release from muscle is not known. We show that reducing the pH of muscle by the addition of lactic acid also stimulates ATP release, and that inhibition of a membrane chloride channel called cystic fibrosis transmembrane conductance regulator (CFTR) inhibits this ATP release. These results suggest that the reduction in pH during muscle contractions might be responsible for triggering the ATP release and that the mechanism by which ATP leaves the cell involves CFTR. © 2010 The Authors. Journal compilation © 2010 The Physiological Society.
Persistent Identifierhttp://hdl.handle.net/10722/139668
ISSN
2015 Impact Factor: 4.731
2015 SCImago Journal Rankings: 2.670
PubMed Central ID
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council10206730
10207994
University of Hong Kong Committee on Research & Conference Grants200807176238
Funding Information:

We are grateful to Mr M. K. Yip and Mr C. P. Mok for technical assistance. This work was funded by Research Grants Council Direct Allocation Grants nos 10206730 and 10207994 and grant no. 200807176238 from the University of Hong Kong Committee on Research & Conference Grants.

References

 

DC FieldValueLanguage
dc.contributor.authorTu, Jen_HK
dc.contributor.authorLe, Gen_HK
dc.contributor.authorBallard, HJen_HK
dc.date.accessioned2011-09-23T05:53:13Z-
dc.date.available2011-09-23T05:53:13Z-
dc.date.issued2010en_HK
dc.identifier.citationJournal Of Physiology, 2010, v. 588 n. 22, p. 4563-4578en_HK
dc.identifier.issn0022-3751en_HK
dc.identifier.urihttp://hdl.handle.net/10722/139668-
dc.description.abstractThe present study was performed to investigate the effect of acidosis on the efflux of ATP from skeletal muscle. Infusion of lactic acid to the perfused hindlimb muscles of anaesthetised rats produced dose-dependent decreases in pH and increases in the interstitial ATP of extensor digitorum longus (EDL) muscle: 10 mm lactic acid reduced the venous pH from 7.22 ± 0.04 to 6.97 ± 0.02 and increased interstitial ATP from 38 ± 8 to 67 ± 11 nm. The increase in interstitial ATP was well-correlated with the decrease in pH (r2= 0.93; P < 0.05). Blockade of cellular uptake of lactic acid using α-cyano-hydroxycinnamic acid abolished the lactic acid-induced ATP release, whilst infusion of sodium lactate failed to depress pH or increase interstitial ATP, suggesting that intracellular pH depression, rather than lactate, stimulated the ATP efflux. Incubation of cultured skeletal myoblasts with 10 mm lactic acid significantly increased the accumulation of ATP in the bathing medium from 0.46 ± 0.06 to 0.76 ± 0.08 μm, confirming the skeletal muscle cells as the source of the released ATP. Acidosis-induced ATP efflux from the perfused muscle was abolished by CFTRinh-172, a specific inhibitor of the cystic fibrosis transmembrane conductance regulator (CFTR), or glibenclamide, an inhibitor of both KATP channels and CFTR, but it was not affected by atractyloside, an inhibitor of the mitochondrial ATP transporter. Silencing of the CFTR gene using an siRNA abolished the acidosis-induced increase in ATP release from cultured myoblasts. CFTR expression on skeletal muscle cells was confirmed using immunostaining in the intact muscle and Western blotting in the cultured cells. These data suggest that depression of the intracellular pH of skeletal muscle cells stimulates ATP efflux, and that CFTR plays an important role in the release mechanism. It is known that exercise reduces the pH of muscle, and also stimulates the release of ATP from muscle cells. This ATP is converted to adenosine in the extracellular space; adenosine relaxes blood vessels, which helps to increase the blood flow to the exercising muscle. The mechanism of ATP release from muscle is not known. We show that reducing the pH of muscle by the addition of lactic acid also stimulates ATP release, and that inhibition of a membrane chloride channel called cystic fibrosis transmembrane conductance regulator (CFTR) inhibits this ATP release. These results suggest that the reduction in pH during muscle contractions might be responsible for triggering the ATP release and that the mechanism by which ATP leaves the cell involves CFTR. © 2010 The Authors. Journal compilation © 2010 The Physiological Society.en_HK
dc.languageengen_US
dc.publisherWiley-Blackwell Publishing Ltd.. The Journal's web site is located at http://www.wiley.com/bw/journal.asp?ref=0022-3751en_HK
dc.relation.ispartofJournal of Physiologyen_HK
dc.rightsThe definitive version is available at www3.interscience.wiley.com-
dc.subject.meshAcidosis, Lactic - metabolism-
dc.subject.meshAdenosine Triphosphate - metabolism-
dc.subject.meshBiological Transport, Active - physiology-
dc.subject.meshCystic Fibrosis Transmembrane Conductance Regulator - antagonists and inhibitors - physiology-
dc.subject.meshMuscle, Skeletal - metabolism-
dc.titleInvolvement of the cystic fibrosis transmembrane conductance regulator in the acidosis-induced efflux of ATP from rat skeletal muscleen_HK
dc.typeArticleen_HK
dc.identifier.emailBallard, HJ: ballard@hkucc.hku.hken_HK
dc.identifier.authorityBallard, HJ=rp00367en_HK
dc.description.naturelink_to_OA_fulltext-
dc.identifier.doi10.1113/jphysiol.2010.195255en_HK
dc.identifier.pmid20819945-
dc.identifier.pmcidPMC3008858-
dc.identifier.scopuseid_2-s2.0-78449235699en_HK
dc.identifier.hkuros196045en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-78449235699&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume588en_HK
dc.identifier.issue22en_HK
dc.identifier.spage4563en_HK
dc.identifier.epage4578en_HK
dc.identifier.eissn1469-7793-
dc.identifier.isiWOS:000284276000022-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridTu, J=7202821423en_HK
dc.identifier.scopusauthoridLe, G=51863749000en_HK
dc.identifier.scopusauthoridBallard, HJ=7005286310en_HK
dc.identifier.citeulike8297377-

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