Antispasmodic effects of alcoholic extracts from oral formulation “prasaplai” on isolated rat uterine muscle

Abstract

This study investigated the spasmolytic effect of the alcoholic extracts from polyherbal formulation “Prasaplai” (PSP01 and PSP02), in comparison with the alcoholic extract from Zingiber cassumunar Roxb. (PSPoil), on the in vitro model of isolated rat uterine horn. The result indicated that all of the test materials significantly relaxed the muscle tension either developed spontaneously or developed by pretreatment with ACh (1µM), oxytocin (2 nM), PGF2α (1µM) and KCl (50 mM). The inhibitory effects were concentration-dependent. In addition, all of the test extracts (100 µg/ml) significantly inhibited the contraction induced by CaCl2 in high K+-Ca2+-free condition and vanadate- induced contraction in Ca2+-free condition. Both PSP01 and PSP02 were equivalent in inhibiting uterine contraction with the higher potency than plai oil (PSPoil) or its major herbal ingredient (sabinene and terpinen-4-ol). Thus, it was likely that there were other ingredients in the whole preparation involving in its relaxation effects. The plausible mechanisms of actions of the alcoholic extracts involved either inhibiting a rising of free cytosolic Ca2+ or Ca2+-dependent signaling pathway. Furthermore, the actions of these extracts were not mediated through β2-adrenoceptors. Further studies could be in need to clarify its influence on intracellular Ca2+level.