dc.contributor.advisor |
Moustafa, Esam |
en |
dc.contributor.author |
De Souza, Maria José Lina |
en |
dc.date.accessioned |
2007-08-28T06:07:38Z |
en |
dc.date.available |
2007-08-28T06:07:38Z |
en |
dc.date.issued |
1983 |
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dc.identifier |
THESIS 83-182 |
en |
dc.identifier.citation |
Thesis (PhD--Biochemistry)--University of Auckland, 1983 |
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dc.identifier.uri |
http://hdl.handle.net/2292/1528 |
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dc.description |
Full text is available to authenticated members of The University of Auckland only. |
en |
dc.description.abstract |
1. Adult rat heart muscle cells were isolated after retrograde perfusion of the heart with a collagenase-containing solution. About 80% of the isolated cells were elongated and excluded trypan blue.
2. Binding of (-) [3H] dihydroalprenolol ([3H]DHA) to isolated myocardial cells did not fulfil a major criterion for β-adrenoceptor binding, namely, stereoselectivity. This was not due to the absence of β-adrenoceptors in myocardial cells as [3H]DHA binding to particulate material prepared from these cells was stereoselective.
Results of experiments carried out in an attempt to explain the lack of stereoselective binding of [3H] DHA to whole myocardial cells were explained.
3. Binding of (±)[125I] iodocyanopindolol ([125I]CYP) to isolated myocardial cells was saturable and stereoselective. The order of potency of β-agonists in competing for [125I] CYP binding sites was the same as their relative potency in stimulating cyclic AMP production. Dissociation constants for β-antagonists estimated from competition for [125I]CYP binding sites correlated with those estimated from inhibition of isoprenaline-stimulated cyclic AMP production.
Scatchard analysis of [125I]CYP saturation isotherms indicated that binding was to a single class of sites and the KD was 37 pM. From the Bmax, the number of β-adrenoceptors per cell was calculated assuming that each receptor site binds to one molecule of radioligand. The number of β-adrenoceptors per cell increased in proportion to the cell size during growth of the heart within the range investigated (0.26 to 0.98 g wet weight). However, the number of β-adrenoceptors per μm2 of the cell surface ares was constant 25 β-adrenoceptors per μm2).
The compound Ro 03-7894, reported to be an irreversible β-antagonist, could not be used to block varying proportions of myocardial cell β-adrenoceptors in order to determine cyclic AMP production coupled to the remaining receptors, since its binding to isolated myocardial cells dissociated after washing.
Evidence for the presence of "spare" β-adrenoceptors in isolated myocardial cells was obtained by using non-radioactive cyanopindolol to block varying proportions of receptors and then determining cyclic AMP production coupled to the remaining receptors. Myocardial cells produced maximal amounts of isoprenaline-stimulated cyclic AMP despite blockade of about 50% of the β-adrenoceptors. |
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dc.language.iso |
en |
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dc.publisher |
ResearchSpace@Auckland |
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dc.relation.ispartof |
PhD Thesis - University of Auckland |
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dc.relation.isreferencedby |
UoA9921936414002091 |
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dc.rights |
Restricted Item. Available to authenticated members of The University of Auckland. |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
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dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
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dc.title |
Beta adrenoceptors and cyclic amp production in muscle cells isolated from adult heart |
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dc.type |
Thesis |
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thesis.degree.discipline |
Biochemistry |
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thesis.degree.grantor |
The University of Auckland |
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thesis.degree.level |
Doctoral |
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thesis.degree.name |
PhD |
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dc.rights.holder |
Copyright: The author |
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dc.identifier.wikidata |
Q112846625 |
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