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Comparison of effects of M-cholinergic compounds on m-acetylcholine receptors in rat cortex parotid gland and longitudinal muscle from small intestine of guinea pig

Yu Aiyao, Jin Guozhang, K C Kin, Xu Jian, Yu Leiping

Shanghai Institute of Materia Medica, Chinese Academy of Sciences. Shanghai, China

Abstract

[~(3)H]-QNB was used as a radioligand for M-acetylcholine receptors (M-AChR) binding in the experiments of competitive inhibition by M-cholinergic agonists and antagonists with the homogenate preparations of rat cortex, parotid gland, and longitudinal muscle from small intestine of guinea pig. With the regression computation (dose-response equation), the slopes of these compounds were all approximate to 1. Thus it was indicated that they acted in the same way on M-AChR (or receptor sites). The rank order of potency of receptor binding assay (IC_(50)) in rat cortex was QNB>atropine, scopolamine>benzhexal>M-8218>B-7601>M-8225>7911, but that in the rat parotid gland was signifcantly different, i.e. M-8218>QNB>7911>M-8225>B-7601>benzhexal>atropine>scopolamine. In particular, the potencies of atropine and scopolamine in the rat cortex were 111 and 316.6 times as active respectively as those in the rat parotid gland. It is ,therefore, suggested that M-AChR in the different target organs have some specific characteristics to be found by various M-antagonists.

Key words: Scopolamin;QNB;M-8218;Alpha, #beta#-hydroxy-g #beta#-acetoxynortropane;M-acetylcholine receptors in rat parotid gland;M-acetyloholine receptor in rat cortex;M-acetylcholine receptors in longitudinal muscle of guinea pig;

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Citing This Article：

Yu Aiyao, Jin Guozhang, K C Kin, Xu Jian, Yu Leiping. Comparison of effects of M-cholinergic compounds on m-acetylcholine receptors in rat cortex parotid gland and longitudinal muscle from small intestine of guinea pig . Acta Physiol Sin 1985; 37 (3): (in Chinese with English abstract).