En 1680-6433 2008-2177 Antispasmodic effect of Physalis alkekengi fruit extract Background: Studies have shown that Physalis alkekengi reduces implantation and induces antifertility in rat. In Iranian traditional medicine it is believed that this plant has abortifacient and antifertility activities. Objective: The goal of this study was to evaluate the effect of Physalis alkekengi ripe fruit hydroalcoholic extract (PFE) on uterine contractility and its possible mechanism(s). Materials and Methods: Extraction of Physalis alkekengi fruit was carried out by maceration method (70% alcohol). Uterus was dissected out from adult non-pregnant rat (Wistar) and contracted by KCl (60mM) or oxytocin (10mU/ml) in an organ bath containing De Jalon solution and the effect of PFE on the uterine contractions was investigated. Furthermore, the role of α- and β-adrenoceptors, opioid receptors, nitric oxide and cyclic guanosine monophosphate synthesis inhibitors on the extract effects were evaluated. Results: KCl- and oxytocin-induced uterine contractions were inhibited (p<0.001) by the cumulative concentrations of the extract in a concentration dependent manner. Incubation of uterus with propranolol (1μM) and L-NAME (100μM) attenuated the PFE antispasmodic effect (p<0.05). But the PFE effect was unaffected by phentolamine (1μM), naloxone (1μM) or methylene blue (10μM). In Ca2+-free with high potassium (60mM) De Jalon solution, cumulative concentrations of CaCl2 (0.1-0.5mM) induced uterine contraction concentration-dependently (p<0.001). Uterus incubation (5min) with PFE (0.25-1.75mg/ml) attenuated the CaCl2–induced contractions (p<0.05). Conclusion: It seems that the extract induced antispasmodic effect mainly via calcium influx blockade and partially through blocking β-adrenoceptors and nitric oxide (NO) synthesis. However, neither α-adrenoceptors nor opioid receptors or cGMP synthesis were involved. Background: Studies have shown that Physalis alkekengi reduces implantation and induces antifertility in rat. In Iranian traditional medicine it is believed that this plant has abortifacient and antifertility activities. Objective: The goal of this study was to evaluate the effect of Physalis alkekengi ripe fruit hydroalcoholic extract (PFE) on uterine contractility and its possible mechanism(s). Materials and Methods: Extraction of Physalis alkekengi fruit was carried out by maceration method (70% alcohol). Uterus was dissected out from adult non-pregnant rat (Wistar) and contracted by KCl (60mM) or oxytocin (10mU/ml) in an organ bath containing De Jalon solution and the effect of PFE on the uterine contractions was investigated. Furthermore, the role of α- and β-adrenoceptors, opioid receptors, nitric oxide and cyclic guanosine monophosphate synthesis inhibitors on the extract effects were evaluated. Results: KCl- and oxytocin-induced uterine contractions were inhibited (p<0.001) by the cumulative concentrations of the extract in a concentration dependent manner. Incubation of uterus with propranolol (1μM) and L-NAME (100μM) attenuated the PFE antispasmodic effect (p<0.05). But the PFE effect was unaffected by phentolamine (1μM), naloxone (1μM) or methylene blue (10μM). In Ca2+-free with high potassium (60mM) De Jalon solution, cumulative concentrations of CaCl2 (0.1-0.5mM) induced uterine contraction concentration-dependently (p<0.001). Uterus incubation (5min) with PFE (0.25-1.75mg/ml) attenuated the CaCl2–induced contractions (p<0.05). Conclusion: It seems that the extract induced antispasmodic effect mainly via calcium influx blockade and partially through blocking β-adrenoceptors and nitric oxide (NO) synthesis. However, neither α-adrenoceptors nor opioid receptors or cGMP synthesis were involved. Rat, Uterus, Physalis alkekengi, Antispasmodic. Rat, Uterus, Physalis alkekengi, Antispasmodic. 193 198 Mohammad Kazem Gharib Naseri Mohammad Kazem Gharib Naseri Gharibnaseri_m@yahoo.com No Maryam Mohammadian Maryam Mohammadian No Zahra Gharib Naseri Pharm Zahra Gharib Naseri Pharm No