File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Conference Paper: A dual effect of melatonin on smooth muscle: role of tyrosine protein kinase

TitleA dual effect of melatonin on smooth muscle: role of tyrosine protein kinase
Authors
Issue Date1998
PublisherS Karger AG. The Journal's web site is located at http://www.karger.com/NSG
Citation
The 1998 Annual Physiology Symposium, Hong Kong, China, 24-25 April 1998. In Biological Signals and Receptors, v. 7 n. 5, p. 269 How to Cite?
AbstractHigh affinity melatonin binding sites have been localized in quail caecum (Poon AMS, et al, J Pineal Res 1997;23/5). In this study, the muscular response of the same subject to melatonin was tested. Under normal conditions (Krebs, 37 ° C, pH 7.45) strips and rings from quail caecum developed spontaneous phasic contractions. Neither activator (phorbol ester) nor inhibitor (calphostin C) of protein kinase C (PKC) were able to modify these contractile responses. Melatonin (1 pM–100 nM) similar to epidermal growth factor (EGF) (50–200 ng/ml), which is known to activate receptor tyrosine kinase, potentiated both the amplitude and frequency of spontaneous contractions in strips and rings. Further increase of concentrations of both agonists evoked the opposite effect. Nifedipine (100 nM), or cromakalim (3 ÌM, opener of K-channels), or genistein (40 ÌM, inhibitor of tyrosine kinases) completely suppressed spontaneous contractile responses. In contrast, the blocker of K-channels iberiotoxin (25 nM) enhanced the frequency of contractions in rings. Subsequent application of melatonin and EGF reversed this iberiotoxin-induced influence. In rings precontracted with KCl (30 mM), 10 ÌM melatonin and 0.4 Ìg/ml EGF potentiated a muscular tone up to 0.64 + 0.08 g (n = 10) which can be inhibited either by genistein or by nifedipine. Conclusion: These results indicate that spontaneous phasic contractile responses in quail caecum are a function of the activity of L-type Ca-channels and K-channels which seem to be regulated by receptor tyrosine kinase rather than PKC. The binding of melatonin to its receptor is to modulate both the phasic contractions and K-induced response, probably via the activation of protein tyrosine kinase. It is suggested that the dual effect of melatonin on spontaneous contractions is due to the initiation of two competitive events (an increase of inward Ca-current and outward K-current through channels) by this tyrosine kinase.
Descriptionpp. 253–285 of this journal issue contains abstracts of the Annual Physiology Symposium 1998
Persistent Identifierhttp://hdl.handle.net/10722/104890
ISSN
2003 Impact Factor: 3.5

 

DC FieldValueLanguage
dc.contributor.authorKravtsov, GMen_HK
dc.contributor.authorPoon, AMSen_HK
dc.contributor.authorPang, SFen_HK
dc.date.accessioned2010-09-25T22:11:39Z-
dc.date.available2010-09-25T22:11:39Z-
dc.date.issued1998en_HK
dc.identifier.citationThe 1998 Annual Physiology Symposium, Hong Kong, China, 24-25 April 1998. In Biological Signals and Receptors, v. 7 n. 5, p. 269en_HK
dc.identifier.issn1422-4933en_HK
dc.identifier.urihttp://hdl.handle.net/10722/104890-
dc.descriptionpp. 253–285 of this journal issue contains abstracts of the Annual Physiology Symposium 1998-
dc.description.abstractHigh affinity melatonin binding sites have been localized in quail caecum (Poon AMS, et al, J Pineal Res 1997;23/5). In this study, the muscular response of the same subject to melatonin was tested. Under normal conditions (Krebs, 37 ° C, pH 7.45) strips and rings from quail caecum developed spontaneous phasic contractions. Neither activator (phorbol ester) nor inhibitor (calphostin C) of protein kinase C (PKC) were able to modify these contractile responses. Melatonin (1 pM–100 nM) similar to epidermal growth factor (EGF) (50–200 ng/ml), which is known to activate receptor tyrosine kinase, potentiated both the amplitude and frequency of spontaneous contractions in strips and rings. Further increase of concentrations of both agonists evoked the opposite effect. Nifedipine (100 nM), or cromakalim (3 ÌM, opener of K-channels), or genistein (40 ÌM, inhibitor of tyrosine kinases) completely suppressed spontaneous contractile responses. In contrast, the blocker of K-channels iberiotoxin (25 nM) enhanced the frequency of contractions in rings. Subsequent application of melatonin and EGF reversed this iberiotoxin-induced influence. In rings precontracted with KCl (30 mM), 10 ÌM melatonin and 0.4 Ìg/ml EGF potentiated a muscular tone up to 0.64 + 0.08 g (n = 10) which can be inhibited either by genistein or by nifedipine. Conclusion: These results indicate that spontaneous phasic contractile responses in quail caecum are a function of the activity of L-type Ca-channels and K-channels which seem to be regulated by receptor tyrosine kinase rather than PKC. The binding of melatonin to its receptor is to modulate both the phasic contractions and K-induced response, probably via the activation of protein tyrosine kinase. It is suggested that the dual effect of melatonin on spontaneous contractions is due to the initiation of two competitive events (an increase of inward Ca-current and outward K-current through channels) by this tyrosine kinase.-
dc.languageengen_HK
dc.publisherS Karger AG. The Journal's web site is located at http://www.karger.com/NSGen_HK
dc.relation.ispartofBiological Signals and Receptorsen_HK
dc.rightsBiological Signals and Receptors. Copyright © S Karger AG.en_HK
dc.titleA dual effect of melatonin on smooth muscle: role of tyrosine protein kinaseen_HK
dc.typeConference_Paperen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1422-4933&volume=7&issue=5&spage=269&epage=&date=1998&atitle=A+dual+effect+of+melatonin+on+smooth+muscle:+role+of+tyrosine+protein+kinaseen_HK
dc.identifier.emailKravtsov, GM: gmkravts@HKUCC.hku.hken_HK
dc.identifier.emailPoon, AMS: amspoon@hkucc.hku.hken_HK
dc.identifier.emailPang, SF: hrmypsf@hkucc.hku.hken_HK
dc.identifier.authorityPoon, AMS=rp00354en_HK
dc.identifier.doi10.1159/000014551-
dc.identifier.hkuros36981en_HK
dc.identifier.hkuros44362-
dc.identifier.volume7en_HK
dc.identifier.issue5en_HK
dc.identifier.spage269en_HK
dc.identifier.epage269-
dc.publisher.placeSwitzerland-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats