Dihydroergocryptine binding sites in bovine and rat pineal glands
High affinity binding of [3H]dihydroergocryptine (DHE) to crude membrane preparations of bovine and rat pineal glands was examined by a rapid filtration procedure through Whatman GFB paper. Scatchard analysis of bovine pineal membranes revealed a single population of binding sites with Kd = (4.8 ± 1...
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1980
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01651838_v2_n4_p305_Vacas http://hdl.handle.net/20.500.12110/paper_01651838_v2_n4_p305_Vacas |
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| Sumario: | High affinity binding of [3H]dihydroergocryptine (DHE) to crude membrane preparations of bovine and rat pineal glands was examined by a rapid filtration procedure through Whatman GFB paper. Scatchard analysis of bovine pineal membranes revealed a single population of binding sites with Kd = (4.8 ± 1.9) × 10−8M (mean±S.E.M., n= 3 and binding site concentration= 834 ± 103 fmol/mg of protein. When various α- and β-adrenergic agonists or antagonists were tested for their ability to inhibit [3H]DHE binding the following Ki values (μM) were obtained: DHE (0.039), phentolamine (0.102), phenoxybenzomine (0.262), methysergide (0.670), l-epinephrine (2.27), serotonin (3.09), l-norepinephrine (3.20), octopamine (30.3), l-propranolol (1710), l-isoproterenol (〉2000). In order to obtain information on the pre- or postsynaptic location of pineal DHE binding sites, pineal 900 g supernatants were prepared from rats subjected to bilateral superior cervical ganglionectomy or sham-operation 7 days earlier. Ganglionectomy caused a 53% increase in the number of binding sites without changing significantly their Kd (5.2 × 10−8 M and 5.5 × 10−8 M in ganglionectomized and control rats, respectively). These results are compatible with the view that postsynaptic α-adrenoceptors are present in the pineal gland. © 1980, Elsevier/North-Holland Biomedical Press. All rights reserved. |
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