Effect of green tea (Camellia sinensis) extract on the rat diaphragm.

The effect of hot water extract of green tea on skeletal muscle and its neurotransmission was studied employing innervated and denervated rat diaphragm. Green tea extract (GTE) has a facilitatory effect at lower concentrations and a paralytic effect at higher concentrations on skeletomotor function. GTE did not have any effect on direct twitch responses or on acetylcholine (ACh) and KCl induced contractures of denervated rat diaphragm and it antagonised the submaximal paralytic effect of D-tubocurarine and decamethonium. GTE-induced facilitation and inhibition were nullified in the presence of magnesium chloride. Nifedipine, reduced GTE-induced facilitation as well as inhibition of twitch responses as a function of its concentration. It was suggested that GTE might act on Ca2+ channels at the skeletomotor junction. The effect of crude polyphenol on neuromuscular junctions was found to be similar to that of GTE. Therefore, it is suggested that the crude polyphenol content of GTE was the active constituent responsible for its effect on neuromuscular junction.