File Download
  Links for fulltext
     (May Require Subscription)
  • Find via Find It@HKUL
Supplementary

Conference Paper: Connexin-hemichannels are Involved in Acidosis-induced ATP Release from Skeletal Myocytes

TitleConnexin-hemichannels are Involved in Acidosis-induced ATP Release from Skeletal Myocytes
Authors
Issue Date2013
PublisherHong Kong College of Cardiology. The Journal's web site is located at http://www.hkcchk.com/journals.php#3
Citation
The 17th Annual Scientific Meeting of the Institute of Cardiovascular Science and Medicine (ICSM), Hong Kong, China, 23 November 2013. In Journal of the Hong Kong College of Cardiology, 2013, v. 21 n. 2, p. 67, abstract no. OP7 How to Cite?
AbstractATP is an important extracellular signalling molecule which contributes to exercise vasodilation. We have previously shown that the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in acidosis-induced ATP release from skeletal muscle. However, it is still unknown whether ATP is released through CFTR itself or whether CFTR regulates a separate ATPrelease channel. So we investigated: (1) the pathway responsible for CFTR activation in myocytes at low pH; (2) whether connexin (Cx) hemichannels were involved in the acidosis-induced ATP release from skeletal muscle. Lactic acid (10 mM) increased the intracellular cAMP and the extracellular ATP in L6 skeletal myocytes. Similarly, the cAMP-elevating agent, forskolin, increased extracellular ATP. The phosphodiesterase inhibitor, IBMX, increased extracellular ATP in the absence or presence of lactic acid. CFTR phosphorylation was increased by the addition of forskolin alone, and further increased by forskolin plus dibutyryl-cAMP and IBMX, but the forskolininduced increase in CFTR phosphorylation was inhibited by the PKA inhibitor, KT5720. Whereas KT5720 inhibited acidosis-induced ATP release from myocytes. These data suggest that skeletal muscle CFTR is activated through the cAMP/PKA pathway at low pH. RT-PCR indicated that cultured rat L6 skeletal myocytes expressed mRNA for both Cx40 and Cx43, but Cx40 was expressed only weakly in western blot, whereas Cx43 was strongly expressed. Co-immunoprecipitation results showed that CFTR and Cx43 were associated with each other in the cell membrane. A Cx43 over-expression model was created by transfecting myocytes with a Cx43 plasmid: Cx43 over-expression was confirmed using western blot. Cx43 over-expressing myocytes released significantly more ATP than control myocytes at pH 6.8, suggesting that Cx43 may be involved in acidosis-induced ATP release, whereas silencing Cx43 expression using siRNA inhibited the acidosis-induced ATP release. Over-expression of CFTR alone did not alter ATP release from myocytes, whereas co-over-expression of CFTR with Cx43 increased ATP release significantly more than over-expression of Cx43 alone. These data suggest that Cx43 co-localises with CFTR in the myocyte membrane, and that it may be involved in ATP release during acidosis; further investigation is required to determine whether and how CFTR interacts with Cx43 to induce ATP release.
DescriptionOral Presentation
Persistent Identifierhttp://hdl.handle.net/10722/203341
ISSN
2015 SCImago Journal Rankings: 0.102

 

DC FieldValueLanguage
dc.contributor.authorLu, Len_US
dc.contributor.authorTu, Jen_US
dc.contributor.authorBallard, HJen_US
dc.date.accessioned2014-09-19T14:09:00Z-
dc.date.available2014-09-19T14:09:00Z-
dc.date.issued2013en_US
dc.identifier.citationThe 17th Annual Scientific Meeting of the Institute of Cardiovascular Science and Medicine (ICSM), Hong Kong, China, 23 November 2013. In Journal of the Hong Kong College of Cardiology, 2013, v. 21 n. 2, p. 67, abstract no. OP7en_US
dc.identifier.issn1027-7811-
dc.identifier.urihttp://hdl.handle.net/10722/203341-
dc.descriptionOral Presentation-
dc.description.abstractATP is an important extracellular signalling molecule which contributes to exercise vasodilation. We have previously shown that the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in acidosis-induced ATP release from skeletal muscle. However, it is still unknown whether ATP is released through CFTR itself or whether CFTR regulates a separate ATPrelease channel. So we investigated: (1) the pathway responsible for CFTR activation in myocytes at low pH; (2) whether connexin (Cx) hemichannels were involved in the acidosis-induced ATP release from skeletal muscle. Lactic acid (10 mM) increased the intracellular cAMP and the extracellular ATP in L6 skeletal myocytes. Similarly, the cAMP-elevating agent, forskolin, increased extracellular ATP. The phosphodiesterase inhibitor, IBMX, increased extracellular ATP in the absence or presence of lactic acid. CFTR phosphorylation was increased by the addition of forskolin alone, and further increased by forskolin plus dibutyryl-cAMP and IBMX, but the forskolininduced increase in CFTR phosphorylation was inhibited by the PKA inhibitor, KT5720. Whereas KT5720 inhibited acidosis-induced ATP release from myocytes. These data suggest that skeletal muscle CFTR is activated through the cAMP/PKA pathway at low pH. RT-PCR indicated that cultured rat L6 skeletal myocytes expressed mRNA for both Cx40 and Cx43, but Cx40 was expressed only weakly in western blot, whereas Cx43 was strongly expressed. Co-immunoprecipitation results showed that CFTR and Cx43 were associated with each other in the cell membrane. A Cx43 over-expression model was created by transfecting myocytes with a Cx43 plasmid: Cx43 over-expression was confirmed using western blot. Cx43 over-expressing myocytes released significantly more ATP than control myocytes at pH 6.8, suggesting that Cx43 may be involved in acidosis-induced ATP release, whereas silencing Cx43 expression using siRNA inhibited the acidosis-induced ATP release. Over-expression of CFTR alone did not alter ATP release from myocytes, whereas co-over-expression of CFTR with Cx43 increased ATP release significantly more than over-expression of Cx43 alone. These data suggest that Cx43 co-localises with CFTR in the myocyte membrane, and that it may be involved in ATP release during acidosis; further investigation is required to determine whether and how CFTR interacts with Cx43 to induce ATP release.-
dc.languageengen_US
dc.publisherHong Kong College of Cardiology. The Journal's web site is located at http://www.hkcchk.com/journals.php#3-
dc.relation.ispartofJournal of the Hong Kong College of Cardiologyen_US
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleConnexin-hemichannels are Involved in Acidosis-induced ATP Release from Skeletal Myocytesen_US
dc.typeConference_Paperen_US
dc.identifier.emailBallard, HJ: ballard@hkucc.hku.hken_US
dc.identifier.authorityBallard, HJ=rp00367en_US
dc.description.naturepublished_or_final_version-
dc.identifier.hkuros240444en_US
dc.identifier.volume21en_US
dc.identifier.issue2-
dc.identifier.spage67, abstract no. OP7en_US
dc.identifier.epage67, abstract no. OP7en_US
dc.publisher.placeHong Kong-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats