Effect of polyphloretin phosphate on the response of non-gravid rat uterus to folkloric and standard oxytocics in vitro

Polyphloretin phosphate (PPP) has been reported by previous workers to be a specific antagonist of prostaglandin (PGE(1), PGE(2) & PGF(2 alpha))-induced contractions of isolated jird colon, gerbil colon, guinea pig ileum, and rabbit jejunum. In the present study, we examined the effect of PPP on uterotonic activities of crude papaya latex (a folkloric oxytocic), PGF(2 alpha), oxytocin, acetylcholine, and 5-hydroxytryptamine (standard oxytocics) on non-gravid, oestrogen-primed (50 microg/kg) rats in vitro. The effect of PPP on the oxytocics was evaluated qualitatively by incubating the tissues in PPP (25 - 400 microg/ml) for 20 min prior to the addition of a constant concentration of each oxytocic. PPP concentration dependently inhibited the contractile response of the uterine muscles to all the oxytocics. The inhibition was reversible after washing out the drugs. Results of the present study suggest that PPP is a non-specific and reversible antagonist of the response of non-gravid rat uterine smooth muscle to oxytocics in vitro. The specificity of PPP as a prostaglandin antagonist could therefore be species/tissue dependent.