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Differences between the α 2 ‐adrenoceptor in rat submaxillary gland and the α 2A ‐ and α 2B ‐adrenoceptor subtypes
Author(s) -
Michel Anton D.,
Loury Da.,
Whiting Roger L.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb14618.x
Subject(s) - rauwolscine , medicine , endocrinology , submandibular gland , alpha (finance) , phentolamine , prazosin , submaxillary gland , oxymetazoline , chemistry , kidney , salivary gland , adrenergic receptor , receptor , biology , antagonist , construct validity , nursing , patient satisfaction
1 The α 2 ‐adrenoceptors of rat submaxillary gland, labelled with [ 3 H]‐rauwolscine, were characterized by use of a range of subtype selective ligands and were compared to rabbit spleen α 2A ‐adrenoceptors and rat kidney α 2B ‐adrenoceptors. 2 In rat submaxillary gland, [ 3 H]‐rauwolscine labelled an apparently homogeneous population of binding sites with relatively low affinity ( K d = 11.65 n m ) compared to the affinity in rat kidney ( K d = 2.18 n m ) and rabbit spleen ( K d = 4.64 n m ). 3 In competition studies using 16 ligands the α 2 ‐adrenoceptors in rat submaxillary gland appeared to differ from both the α 2A ‐adrenoceptor of rabbit spleen ( r = 0.62) and also the α 2B ‐adrenoceptor of rat kidney ( r = 0.28). 4 The affinity data obtained with benoxathian, imiloxan and WB 4101 indicated the presence of an α 2B ‐adrenoceptor in rat submaxillary gland. However, data for chlorpromazine, oxymetazoline, spiroxatrine and xylometazoline indicated that submaxillary gland α 2 ‐adrenoceptors were of the α 2A subtype. The affinity estimate for prazosin in rat submaxillary gland was intermediate between its affinity at the α 2A ‐ and α 2B ‐adrenoceptors while affinity estimates for idazoxan and phentolamine in rat submaxillary gland were greater than those obtained at either the α 2A ‐ or α 2B ‐adrenoceptor. 5 These data indicate that rat submaxillary gland α 2 ‐adrenoceptors differ from the α 2A ‐ and α 2B ‐adrenoceptors found in rabbit spleen and rat kidney, respectively.