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Dicentrine is preferentially antagonistic to rat aortic than splenic alpha 1-adrenoceptor stimulation
1Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur 57000, Malaysia.
Aim:
Dicentrine is a known alpha 1-adrenoceptor antagonist, but its alpha 1-adrenoceptor subtype selectivity has not yet been determined. We therefore, investigated the putative alpha 1-adrenoceptor subtype selectivity of this agent.
Methods:
Graded isometric contractile responses of rat aortic rings and spleen to phenylephrine were observed in the absence or presence of various concentrations of dicentrine. The pA2 values for dicentrine were determined.
Results:
Aortic tissues were more sensitive to phenylephrine-induced contraction than the spleen tissues. Dicentrine was approximately 100 times more potent as an antagonist to the aortic contraction, than it was to the splenic contractions.
Conclusion:
Dicentrine is an alpha 1-adrenoceptor antagonist which is more selective towards the putative alpha 1D-adrenoceptor subtype of the rat aorta than the alpha 1B-adrenoceptor of the spleen.