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. 1978 Apr;62(4):543–548. doi: 10.1111/j.1476-5381.1978.tb07759.x

Biochemical evidence for the dual action of labetalol on alpha- and beta-adrenoceptors.

M Aggerbeck, G Guellaen, J Hanoune
PMCID: PMC1668053  PMID: 26446

Abstract

1 Labetalol (AH 5158A) inhibited the adrenaline-stimulated adenylate cyclase activity of rat liver and heart. This drug had no effect on basal or guanosine triphosphate (GTP)-activated adenylate cyclase activities. 2 Labetalol displaced the binding of the specific ligands [3H]-dihydroergocryptine and (-)-[3H]-dihydroalprenolol from their respective alpha and beta-adrenoceptors in rat heart and liver. The affinity of labetalol was 10 fold higher for the beta- than for the alpha-adrenoceptor. It appeared to be 10 to 100 times less potent than phentolamine in blocking alpha-adrenoceptors and 5 to 10 times less potent than propranolol in blocking beta-receptors. 3 It is concluded that labetalol exerts its dual alpha- and beta-antagonism by acting directly on the plasma membranes, where it binds competitively to alpha- and beta-adrenoceptors.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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