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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
2
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pubmed:dateCreated |
1978-3-29
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pubmed:abstractText |
Binding of [(3)H]dihydroergocryptine to platelet lysates appears to have all the characteristics of binding to alpha-adrenergic receptors. At 25 degrees C binding reaches equilibrium within 20 min and is reversible upon addition of excess phentolamine. Binding is saturable with 183+/-22 fmol of [(3)H]dihydroergocryptine bound per mg of protein at saturation, corresponding to 220+/-26 sites per platelet. Kinetic and equilibrium studies indicate the dissociation constant of [(3)H]dihydroergocryptine for the receptors is 1-3 nM. The specificity of the binding sites is typical of an alpha-adrenergic receptor. Catecholamine agonists compete for occupancy of the [(3)H]dihydroergocryptine binding sites with an order of potency (-)epinephrine> (-)norepinephrine>> (-)isoproterenol. Stereospecificity was demonstrated inasmuch as the (+)isomers of epinephrine and norepinephrine were 10-20-fold less potent than the (-)isomers. The potent alpha-adrenergic antagonists phentolamine, phenoxybenzamine, and yohimbine competed potently for the sites, whereas beta-antagonists such as propranolol and dichlorisoproterenol were quite weak. Dopamine and serotonin competed only at high concentrations (0.1 mM). The [(3)H]dihydroergocryptine binding sites could also be demonstrated in intact platelets where they displayed comparable specificity, stereospecificity, and saturability. Saturation binding studies with the intact platelets indicated 220+/-45 receptors per platelet, in good agreement with the value derived from studies with platelet lysates. Ability of alpha-adrenergic agonists to inhibit adenylate cyclase and of alpha-adrenergic antagonists to antagonize this inhibitory effect directly paralleled ability to interact with the [(3)H]dihydroergocryptine binding sites. These data demonstrate the feasibility of directly studying alpha-adrenergic receptor binding sites in human platelets with [(3)H]dihydroergocryptine.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-14087010,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-14175,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-14907713,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-176581,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-17827,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-186492,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4202581,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4306955,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4310361,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4316427,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4330513,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4333938,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4335547,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4360127,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4368448,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4425095,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-4827395,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-5232334,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-5785133,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-6065889,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-6960,
http://linkedlifedata.com/resource/pubmed/commentcorrection/23392-825511
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
AIM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Feb
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pubmed:issn |
0021-9738
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
61
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
395-402
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:23392-Adenylate Cyclase,
pubmed-meshheading:23392-Adrenergic alpha-Agonists,
pubmed-meshheading:23392-Adrenergic alpha-Antagonists,
pubmed-meshheading:23392-Binding, Competitive,
pubmed-meshheading:23392-Blood Platelets,
pubmed-meshheading:23392-Dihydroergotoxine,
pubmed-meshheading:23392-Humans,
pubmed-meshheading:23392-Kinetics,
pubmed-meshheading:23392-Platelet Aggregation,
pubmed-meshheading:23392-Receptors, Adrenergic,
pubmed-meshheading:23392-Receptors, Adrenergic, alpha
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pubmed:year |
1978
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pubmed:articleTitle |
Identification of alpha-adrenergic receptors in human platelets by [3H]dihydroergocryptine binding.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, U.S. Gov't, P.H.S.
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