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Investigation of the subtype of α 2 ‐adrenoceptor mediating prejunctional inhibition of cardioacceleration in the pithed rat heart
Author(s) -
Smith Karen,
Gavin Katherine,
Docherty James R.
Publication year - 1995
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.1476-5381.1995.tb15879.x
Subject(s) - endocrinology , medicine , yohimbine , alpha (finance) , antagonist , ligand (biochemistry) , agonist , alpha 2 adrenergic receptor , chemistry , receptor , biology , construct validity , nursing , patient satisfaction
1 We have investigated the subtype of α 2 ‐adrenoceptor mediating prejunctional inhibition of cardioacceleration in the pithed rat heart in comparison with α 2 ‐adrenoceptor ligand binding sites. 2 In pithed rats, prejunctional α 2 ‐adrenoceptors were investigated in terms of the ability of α 2 ‐adrenoceptor antagonists to shift the inhibitory potency of the α 2 ‐adrenoceptor agonist, xylazine, against the tachycardia to a single electrical stimulus given via the pithing rod. 3 Antagonist potency at prejunctional α 2 ‐adrenoceptors in pithed rat heart was correlated with antagonist affinity at α 2 ‐adrenoceptor ligand binding sites in membranes of rat kidney and submandibular gland labelled with [ 3 H]‐yohimbine. 4 The correlation with the prejunctional α 2 ‐adrenoceptor in pithed rat heart was best for the α 2D ‐adrenoceptor ligand binding site of rat submandibular gland ( r = 0.98, n = 10, P < 0.0001), as compared to correlations with the α 2A ‐adrenoceptor ligand binding site of human platelet ( r = 0.90, n = 9, P <0.001), the x 2B ‐adrenoceptor ligand binding site of rat kidney ( r = 0.82, n = 10, P <0.01) and with published results for the α 2C ‐adrenoceptor ligand binding site ( r = 0.48, n = 6, NS). 5 It is concluded that the functional prejunctional α 2 ‐adrenoceptor of pithed rat heart closely resembles the α 2D ‐adrenoceptor ligand binding site of rat submandibular gland.