Active Fractions And Mechanism Of Aqueous Extract From Persimmon Calyx In The Rat Isolated Diaphragm Preparations

Objective: To investigate effects of the aqueous extract (AE) from Persimmon Calyx and its active fractions on electrically induced contraction in the rat isolated diaphragm preparations. Method: We established a model of contractile response induced by electric stimulation in the rat isolated diaphragm. Effects of AE were investigated in the rat isolated diaphragm preparations with phrenic nerves and the rat isolated diaphragm strips. Results: In the experiments of electrically induced contraction in the rat isolated diaphragm preparations with phrenic nerves, AE (1.2 g/L, 2.4 g/L and 3.6 g/L) increased the amplitude of muscle contraction during initial 0～60min (P<0.05, n=6), then decreased that significently at 180min (P<0.01, n=6). AE also induced biphasic effects in the isolated diaphragm strip preparations, at 1.2 g/L, 1.8 g/L and 2.4 g/L. With the increase in AE concentraction, the initial potentiation became smaller and the inhibitory effect became much stronger. The percentage changes of contractile responses to electric stimulation in draphragm strips pretreated with tubacurarine...