File Download
  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Unusual α-adrenoceptor subtype in canine saphenous vein: comparison to mesenteric vein

TitleUnusual α-adrenoceptor subtype in canine saphenous vein: comparison to mesenteric vein
Authors
Keywords[3H]-rauwolscine
Prazosin
Phenylephrine
Methoxamine
Chloroethylclonidine
Issue Date1996
PublisherNature Publishing Group. The Journal's web site is located at http://www.nature.com/bjp
Citation
British Journal of Pharmacology, 1996, v. 117 n. 7, p. 1535-1543 How to Cite?
Abstract1. We investigated the nature of the adrenoceptors in the dog saphenous vein (DSV) and dog mesenteric vein (DMV) to determine the nature of the unexpected interactions of phenylephrine and methoxamine with rauwolscine in the DSV, i.e. the ability of the putative alpha 2-adrenoceptor antagonist to inhibit competitively contractions to these alpha 1-agonists. Radioligand binding studies were performed in parallel with contractility studies. 2. Functionally, in the DSV, phenylephrine and methoxamine-induced, contractions were antagonized by rauwolscine with Schild slopes of -0.52 and -0.46, respectively and apparent pA2 values of 8.5 and 9.2, respectively. Such antagonism was not observed in the DMV. In the DSV, prazosin competes for [3H]-rauwolscine binding sites with a high and a low affinity binding site (Ki of 1.49 +/- 0.65 and 94.7 +/- 51 microM, n = 6, respectively). 3. Pretreatment with 100 microM chloroethylclonidine (CEC) for 15 min abolished [3H]-prazosin binding in microsomes from both veins and reduced binding (Bmax) of [3H]-rauwolscine in microsomes by 55.1 +/- 0.8% (n = 3) in the DSV but did not affect the Bmax in the DMV. CEC pretreatment in the venular rings denuded of endothelium caused persistent contraction in the DSV but not in the DMV. In the DSV, CEC appeared to interact with a single [3H]-rauwolscine binding site. In both the DSV and the DMV, CEC (100 microM) caused a significant shift in the EC50 values for phenylephrine and methoxamine. Maximum responses in the DMV were significantly attenuated while those in the DSV were unaffected when total tension was considered. 4. Studies of the functional interactions of the DSV and the DMV with WB 4101 or 5-methylurapidil (5-MU) suggested the presence of alpha 1D-adrenoceptors in the DSV and alpha 1A-adrenoceptors in the DMV. The receptors inactivated by CEC in the DMV and DSV may represent some or all of the receptors with properties of alpha 1D and alpha 1A-receptors present in the two veins. Studies of radioligand binding interactions of these two antagonists with [3H]-prazosin, were consistent with the presence of some alpha 1D-receptors in DSV and alpha 1A-receptors in DMV. These findings raise questions about the selectivity of CEC in differentiating alpha 1-adrenoceptor subtypes. 5. B-HT 920 caused contractions in the DSV smaller than those to the alpha 1-agonists but the maximum was not affected by CEC pretreatment. The EC50 values were shifted to the left after CEC. In radioligand binding studies, B-HT 920 competition for [3H]-rauwolscine binding was not significantly affected by CEC pretreatment. 6. These results suggest the presence of unusual alpha-adrenoceptors in the DSV. In addition to alpha 2-adrenoceptors, receptors recognizing rauwolscine as well as prazosin, WB 4101, phenylephrine and methoxamine and susceptible to inactivation by CEC are present. They appear to be, in part, unusual alpha 1D-adrenoceptors.
Persistent Identifierhttp://hdl.handle.net/10722/49293
ISSN
2015 Impact Factor: 5.259
2015 SCImago Journal Rankings: 2.368
PubMed Central ID
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorDaniel, EEen_HK
dc.contributor.authorLow, AMen_HK
dc.contributor.authorGaspar, Ven_HK
dc.contributor.authorLu-Chao, Hen_HK
dc.contributor.authorGreen, Jen_HK
dc.contributor.authorAkrong, Jen_HK
dc.contributor.authorDuerksen, Sen_HK
dc.contributor.authorSoyka, Cen_HK
dc.contributor.authorChen, CKen_HK
dc.contributor.authorBoyd, Jen_HK
dc.contributor.authorKwan, CYen_HK
dc.date.accessioned2008-06-12T06:38:42Z-
dc.date.available2008-06-12T06:38:42Z-
dc.date.issued1996en_HK
dc.identifier.citationBritish Journal of Pharmacology, 1996, v. 117 n. 7, p. 1535-1543en_HK
dc.identifier.issn0007-1188en_HK
dc.identifier.urihttp://hdl.handle.net/10722/49293-
dc.description.abstract1. We investigated the nature of the adrenoceptors in the dog saphenous vein (DSV) and dog mesenteric vein (DMV) to determine the nature of the unexpected interactions of phenylephrine and methoxamine with rauwolscine in the DSV, i.e. the ability of the putative alpha 2-adrenoceptor antagonist to inhibit competitively contractions to these alpha 1-agonists. Radioligand binding studies were performed in parallel with contractility studies. 2. Functionally, in the DSV, phenylephrine and methoxamine-induced, contractions were antagonized by rauwolscine with Schild slopes of -0.52 and -0.46, respectively and apparent pA2 values of 8.5 and 9.2, respectively. Such antagonism was not observed in the DMV. In the DSV, prazosin competes for [3H]-rauwolscine binding sites with a high and a low affinity binding site (Ki of 1.49 +/- 0.65 and 94.7 +/- 51 microM, n = 6, respectively). 3. Pretreatment with 100 microM chloroethylclonidine (CEC) for 15 min abolished [3H]-prazosin binding in microsomes from both veins and reduced binding (Bmax) of [3H]-rauwolscine in microsomes by 55.1 +/- 0.8% (n = 3) in the DSV but did not affect the Bmax in the DMV. CEC pretreatment in the venular rings denuded of endothelium caused persistent contraction in the DSV but not in the DMV. In the DSV, CEC appeared to interact with a single [3H]-rauwolscine binding site. In both the DSV and the DMV, CEC (100 microM) caused a significant shift in the EC50 values for phenylephrine and methoxamine. Maximum responses in the DMV were significantly attenuated while those in the DSV were unaffected when total tension was considered. 4. Studies of the functional interactions of the DSV and the DMV with WB 4101 or 5-methylurapidil (5-MU) suggested the presence of alpha 1D-adrenoceptors in the DSV and alpha 1A-adrenoceptors in the DMV. The receptors inactivated by CEC in the DMV and DSV may represent some or all of the receptors with properties of alpha 1D and alpha 1A-receptors present in the two veins. Studies of radioligand binding interactions of these two antagonists with [3H]-prazosin, were consistent with the presence of some alpha 1D-receptors in DSV and alpha 1A-receptors in DMV. These findings raise questions about the selectivity of CEC in differentiating alpha 1-adrenoceptor subtypes. 5. B-HT 920 caused contractions in the DSV smaller than those to the alpha 1-agonists but the maximum was not affected by CEC pretreatment. The EC50 values were shifted to the left after CEC. In radioligand binding studies, B-HT 920 competition for [3H]-rauwolscine binding was not significantly affected by CEC pretreatment. 6. These results suggest the presence of unusual alpha-adrenoceptors in the DSV. In addition to alpha 2-adrenoceptors, receptors recognizing rauwolscine as well as prazosin, WB 4101, phenylephrine and methoxamine and susceptible to inactivation by CEC are present. They appear to be, in part, unusual alpha 1D-adrenoceptors.en_HK
dc.format.extent388 bytes-
dc.format.mimetypetext/html-
dc.languageengen_HK
dc.publisherNature Publishing Group. The Journal's web site is located at http://www.nature.com/bjpen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject[3H]-rauwolscineen_HK
dc.subjectPrazosinen_HK
dc.subjectPhenylephrineen_HK
dc.subjectMethoxamineen_HK
dc.subjectChloroethylclonidineen_HK
dc.titleUnusual α-adrenoceptor subtype in canine saphenous vein: comparison to mesenteric veinen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0007-1188&volume=117&issue=7&spage=1535&epage=1543&date=1996&atitle=Unusual+α-adrenoceptor+subtype+in+canine+saphenous+vein:+comparison+to+mesenteric+veinen_HK
dc.identifier.emailKwan, CY: cykwan@hkucc.hku.hken_HK
dc.description.naturepublished_or_final_versionen_HK
dc.identifier.pmid8730751-
dc.identifier.pmcidPMC1909456en_HK
dc.identifier.scopuseid_2-s2.0-0029670164-
dc.identifier.isiWOS:A1996UF13800026-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats