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. 1986 Dec;42(4):579-82.
doi: 10.1254/jjp.42.579.

A difference in mode of antagonism between optical isomers of a potent selective alpha 1-adrenoceptor blocker (YM-12617) and norepinephrine in isolated rabbit iris dilator and aorta

Free article

A difference in mode of antagonism between optical isomers of a potent selective alpha 1-adrenoceptor blocker (YM-12617) and norepinephrine in isolated rabbit iris dilator and aorta

I Takayanagi et al. Jpn J Pharmacol. 1986 Dec.
Free article

Abstract

Optical isomers of YM-12617, a potent and selective alpha 1-adrenoceptor blocker, were tested on the rabbit iris dilator and aorta. The order of potency was R(-)-isomer greater than racemate greater than S(+)-isomer. The R(-)-isomer and racemate behaved as an essentially irreversible antagonist to norepinephrine in the iris dilator where the efficacy of norepinephrine was small, although the S(+)-isomer was a competitive antagonist. These drugs behaved as a competitive antagonist of norepinephrine in the aorta where the efficacy of norepinephrine was large.

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