Physiological and pathophysiological significance of co-existence of three subtypes ofα_1-adrenoceptor in heart and blood vessels

摘要

We previously proved thatα_1-adrenoceptor(α_1-AR) contained two subtypes-α_1A andα_1B. Theα_1A-AR showed high affinity to a series of selective antagonists and was not alklated by chlorethylclonidine(CEC). The activation of α_1A-AR induced hydrolysis of phosphoinositol and its mediated smooth muscle contraction was dependent on Ca~2+ entry through the dihydropyridine sensitive calcium channel. theα_1B-AR, however, showed low affinity to the antagonists and was irreversibly blocked by ECE. The activation ofα_1B- AR induced phosphoinositol hydrolysis as well.