Additional evidence for functional subclassification of alpha-2 adrenoceptors based on a new selective antagonist, SKF 104856
| Autor: | J P, Hieble, A C, Sulpizio, R, Edwards, H, Chapman, P, Young, S P, Roberts, T P, Blackburn, M D, Wood, D H, Shah, R M, Demarinis |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Male
Serotonin Guinea Pigs In Vitro Techniques Tritium Binding Competitive Synaptic Transmission Muscle Smooth Vascular Norepinephrine Dogs Vas Deferens Quinoxalines Animals Humans Heart Atria Adrenergic alpha-Antagonists Rats Inbred Strains Benzazepines Receptors Adrenergic alpha Atrial Function Electric Stimulation Rats Brimonidine Tartrate Female Rabbits Adrenergic alpha-Agonists Muscle Contraction |
| Zdroj: | The Journal of pharmacology and experimental therapeutics. 259(2) |
| ISSN: | 0022-3565 |
| Popis: | SKF 104856 (2-vinyl-7-chloro-3,4,5,6-tetrahydro-4-methyl-thieno[4,3,2ef][3] benzazepine) shows a similar selectivity profile to the previously reported alpha adrenoceptor antagonist, SKF 104078 (6-chloro-9-[(3-methyl-2-butenyl)oxy]-3-methyl-1H-2,3,4,5-tetrahydro-3- benzazepine), having the ability to block alpha-1 and postjunctional alpha-2 adrenoceptors, although having little or no activity at most prejunctional alpha-2 adrenoceptors. SKF 104856 is more potent than SKF 104078, and lacks the 5-hydroxytryptamine receptor antagonist activity associated with the earlier compound. The postjunctional vs. prejunctional selectivity of SKF 104856 at alpha-2 adrenoceptors in the same tissue preparation was demonstrated in both canine and human saphenous vein. Concentrations substantially higher than those required to block postjunctional alpha-2 adrenoceptor-agonist induced vasoconstriction had no effect on the ability of norepinephrine, acting on prejunctional alpha-2 adrenoceptors, to inhibit stimulation evoked transmitter overflow in the human tissue, and only a small effect in the canine vein. As observed with SKF 104078, SKF 104856 has some prejunctional alpha-2 adrenoceptor antagonist activity in the rat vas deferens, although the receptor dissociation constant is nearly 50-fold higher than that at the postjunctional alpha-2 adrenoceptor in the canine saphenous vein. The results obtained with SKF 104856 provide additional evidence to support the premise that alpha-2 adrenoceptors can be functionally differentiated. Because SKF 104856 can selectively antagonize certain alpha-2 adrenoceptor-mediated responses, this agent may be a useful tool to evaluate the functional roles of the multiple alpha-2 adrenoceptor subtypes that have been identified in biochemical and molecular studies. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|