THE CHARACTERISTICS OF [3H]‐CLONIDINE BINDING TO ANα‐ADRENOCEPTOR IN MEMBRANES FROM GUINEA‐PIG KIDNEY

B. JARROTT, W. J. LOUIS, R. J. SUMMERS

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Abstract

[3H]‐clonidine binds to membranes prepared from guinea‐pig kidney. At 25°C the binding is rapid and saturable. Scatchard analysis of the binding data showed that the Kd for [3H]‐clonidine binding in kidney membranes is 8.54 nM and the density of binding sites 12.5 pmol/g wet wt. tissue. Hill plots of the binding data showed that there were no cooperative site interactions associated with binding. [3H]‐clonidine binding could be displaced by drugs, the most potent being drugs with a high affinity for the α‐adrenoceptor. The neuroleptic drugs (+)‐butaclamol, ds‐clopenthixol and ds‐flupen‐thixol at high concentration also displaced [3H]‐clonidine binding. Drugs acting as agonists or antagonists of β‐adrenoceptors, histamine receptors, acetylcholine receptors as well as prostaglandins E1 E2, F and F, angiotensin II, arginine vasopressin, naloxone, nalorphine and pargyline had little effect on binding. It is likely that the binding site labelled by [3H]‐clonidine in guinea‐pig kidney membranes is an α‐adrenoceptor similar in some pharmacological aspects to an a2‐adrenoceptor. 1979 British Pharmacological Society

Original languageEnglish
Pages (from-to)663-670
Number of pages8
JournalBritish Journal of Pharmacology
Volume65
Issue number4
DOIs
Publication statusPublished - 1 Jan 1979

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