Mechanism of the tracheal smooth muscle relaxant activity of the Cordia myxa plant extract in sheep

Abstract EN

Isolated tracheal smooth muscle of sheep, which is pharmacologically precontracted by acetylcholine, induces relaxation when exposed to Cordia myxa plant extract.

The aim of the present study was to typify the mechanism of Cordia myxa extract induced by relaxation in the sheep trachea.

1.

Cordia myxa extract relaxed both epithelium-intact and denuded sheep trachea rings contracted by acetylcholine.

The scale of relaxation on Cordia myxa extract was dependent on the treated dose and slightly greatly in epithelium denuded rings than in epithelium-intact preparations.

2.

L-NAME (10 nM-100 uM) but not DNAME completely inhibited the relaxation in a concentration dependent manner.

3.

The Cordia myxa extract -induced relaxation was inhibited by methylene blue (1 -100 uM), and verapamil (100 nM), and removal of extracellular Ca2 +.

In contrast, Cordia myxa extract -induced relaxation was potentiated by Nw-nitro-Larginine (L-NOARG) treatment.

These results put forward that Cordia myxa extract -induced relaxation may be due to nitric oxide from exogenously administered L-arginine as well as endogenous nitric oxide donors such as amino acid and arginine derivatives.

Additional suggestion is that Cordia myxa extract stimulates the expression of nitric oxide synthesis, and its activity for nitric oxide generation is dependent on cytosolic Ca2 + originated from extracellular space.