Abstract
Bovine adrenal medullary membranes display high affinity and saturable binding to [ 3H]mepyramine, a selective H 1 antagonist, with Kd of 1.5 ± 0.1 nM and Bmax of 694 ± 12 fmol/mg protein. [ 3H]Azidobenzpyramine, an azidobenzamide derivative of mepyramine, was synthesized and used to photolabel the high affinity mepyramine binding sites. Following photolysis, a protein component with an approximate molecular weight of 53–58 kDa was shown to be covalently labeled, as judged by gel filtration and SDS/PAGE; labeling being greatly reduced in the presence of excess unlabeled mepyramine. These results indicate that bovine adrenal medulla expresses a large number of H 1 receptors, which are pharmacologically and biochemically indistinguishable from the H 1 receptor of many other tissues of various species.
Published Version
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