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Conference Paper: Attenuated intracellular Ca 2+ response to beta-adrenoceptor stimulation is due to conversion of a 45 kDa Gs-alpha isoform to a 52 kDa Gs-alpha isoform in the heart of chronically hypoxic rat

TitleAttenuated intracellular Ca 2+ response to beta-adrenoceptor stimulation is due to conversion of a 45 kDa Gs-alpha isoform to a 52 kDa Gs-alpha isoform in the heart of chronically hypoxic rat
Authors
Issue Date1999
PublisherMedcom Limited. The Journal's web site is located at http://www.hkcchk.com/journals.php
Citation
The 3rd Annual Scientific Meeting of The Institute of Cardiovascular Science and Medicine (ICSM), Hong Kong, 30 October 1999. In Journal of Hong Kong College of Cardiology, 1999, v. 7 n. 2, p. 135, abstract no. 40 How to Cite?
AbstractThe cardiac responses to β-adrenoceptor stimulation are attenuated in hypertrophied and failing heart. In addition to down-regulation of the β-adrenoceptor receptor it is believed that the intracellular signaling mechanisms may also be altered. In the present study we determined firstly the electrically induced intracellular Ca2+ ([Ca2+]i) transient in response to activation of β-adrenoceptor with isoproterenol (Iso), Gs protein with cholera toxin (CTX) and adenylate cyclase (AC) with forskolin in isolated myocytes of the right hypertrophied rat induced by treatment with 10% oxygen for 4 weeks. The electrically induced intracellular [Ca2+]I transient was determined with a soectrofluorometric method using fura-2A as Ca2- indicator. 1µM Iso, 20µg/ml CTX for 6 h and 1µM forskolin increased the electrically induced [Ca2+]I transient in both types of rats. The response to Iso and CTX was significantly attenuated, ehile that to forskolin not changed, in the right ventricle of chronically hypoxic rats. Secondly we determined with an immunoblotting method the contents of the 45kDa and a 52kDa isoforms of Gsα in the right ventricle of normoxic and hypoxic rats. We found that the 45kDa isoform was significantly reduced, while the 52 kDa protein increased, in the ventricle of hypoxic rats. Since the 45kDa isoform is the active isoform, the attenuated Ca2+ response to activation of Gs-protein may be due to the conversion of the active insoform to the less active isoform in the heart of hypoxic rats. (The study was supported by a grant from the Institute of Cardiovascular Science and Medicine).
Persistent Identifierhttp://hdl.handle.net/10722/105094
ISSN
2015 SCImago Journal Rankings: 0.102

 

DC FieldValueLanguage
dc.contributor.authorPei, JM-
dc.contributor.authorYu, XC-
dc.contributor.authorFung, ML-
dc.contributor.authorCheung, CS-
dc.contributor.authorLeung, MP-
dc.contributor.authorWong, NS-
dc.contributor.authorWong, TM-
dc.date.accessioned2010-09-25T22:19:58Z-
dc.date.available2010-09-25T22:19:58Z-
dc.date.issued1999-
dc.identifier.citationThe 3rd Annual Scientific Meeting of The Institute of Cardiovascular Science and Medicine (ICSM), Hong Kong, 30 October 1999. In Journal of Hong Kong College of Cardiology, 1999, v. 7 n. 2, p. 135, abstract no. 40-
dc.identifier.issn1027-7811-
dc.identifier.urihttp://hdl.handle.net/10722/105094-
dc.description.abstractThe cardiac responses to β-adrenoceptor stimulation are attenuated in hypertrophied and failing heart. In addition to down-regulation of the β-adrenoceptor receptor it is believed that the intracellular signaling mechanisms may also be altered. In the present study we determined firstly the electrically induced intracellular Ca2+ ([Ca2+]i) transient in response to activation of β-adrenoceptor with isoproterenol (Iso), Gs protein with cholera toxin (CTX) and adenylate cyclase (AC) with forskolin in isolated myocytes of the right hypertrophied rat induced by treatment with 10% oxygen for 4 weeks. The electrically induced intracellular [Ca2+]I transient was determined with a soectrofluorometric method using fura-2A as Ca2- indicator. 1µM Iso, 20µg/ml CTX for 6 h and 1µM forskolin increased the electrically induced [Ca2+]I transient in both types of rats. The response to Iso and CTX was significantly attenuated, ehile that to forskolin not changed, in the right ventricle of chronically hypoxic rats. Secondly we determined with an immunoblotting method the contents of the 45kDa and a 52kDa isoforms of Gsα in the right ventricle of normoxic and hypoxic rats. We found that the 45kDa isoform was significantly reduced, while the 52 kDa protein increased, in the ventricle of hypoxic rats. Since the 45kDa isoform is the active isoform, the attenuated Ca2+ response to activation of Gs-protein may be due to the conversion of the active insoform to the less active isoform in the heart of hypoxic rats. (The study was supported by a grant from the Institute of Cardiovascular Science and Medicine).-
dc.languageeng-
dc.publisherMedcom Limited. The Journal's web site is located at http://www.hkcchk.com/journals.php-
dc.relation.ispartofJournal of Hong Kong College of Cardiology-
dc.titleAttenuated intracellular Ca 2+ response to beta-adrenoceptor stimulation is due to conversion of a 45 kDa Gs-alpha isoform to a 52 kDa Gs-alpha isoform in the heart of chronically hypoxic rat-
dc.typeConference_Paper-
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1027-7811&volume=7 &issue=2&spage=135&epage=&date=1999&atitle=Attenuated+intracellular+Ca2++response+to+beta-adrenoceptor+stimulation+is+due+to+conversion+of+a+45+kDa+Gs-alpha+isoform+to+a+52+kDa+Gs-alpha+isoform+in+the+heart+of+chronically+hypoxic+rat.en_HK
dc.identifier.emailFung, ML: fungml@hku.hk-
dc.identifier.emailWong, TM: wongtakm@hkucc.hku.hk-
dc.identifier.authorityFung, ML=rp00433-
dc.identifier.hkuros53373-
dc.identifier.volume7-
dc.identifier.issue2-
dc.identifier.spage135, abstract no. 40-
dc.identifier.epage135, abstract no. 40-
dc.publisher.placeHong Kong-

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