ラット摘出空腸における収縮薬K,Acetylcholine,Baおよび弛緩薬Isoproterenol,Papaverine,Mgの作用機序とくにCaとの関連

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I. Action of spasmogens. Evidence has been obtained suggesting that (1) for all spasmogens tested, phasic contraction is produced by Ca release, the tonic contraction chiefly being maintained by the energy-dependent active influx of Ca, that (2) only in the case of Ba, a direct stimulation to the contractile system of muscle is also partly concerned with contraction, which is implied by the residual contraction by Ba in the Ca-free bath solution, and that (3) K and acetylcholine release Ca from the store of easily releasable Ca, whereas Ba does so, in addition, from the store of less easily releasable Ca. II. Action of relaxants. Summing up the results of various experiments, it is concluded that (1) the relaxing action of isoproterenol on the normal tonus is due chiefly to the pseudo-competitive (or functional) inhibition of Ca influx and Ca release and (2) those of papaverine and Mg to the competitive inhibition of Ca influx and the non-competitive inhibition of the contractile system of muscle, the inhibition of Ca influx being more concerned with the relaxation by Mg than with that by papaverine.
社団法人日本薬理学会の論文