en Original Article Original Article <strong>Background:</strong> 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.<br> <strong>Objective:</strong> 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).<br> <strong>Materials and Methods:</strong>&nbsp;Extraction of <em>Physalis alkekengi</em> 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 &alpha;- and &beta;-adrenoceptors, opioid receptors, nitric oxide and cyclic guanosine monophosphate synthesis inhibitors on the extract effects were evaluated.<br> <strong>Results:</strong> 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 (1&mu;M) and L-NAME (100&mu;M) attenuated the PFE antispasmodic effect (p<0.05). But the PFE effect was unaffected by phentolamine (1&mu;M), naloxone (1&mu;M) or methylene blue (10&mu;M). 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&ndash;induced contractions (p<0.05).<br> <strong>Conclusion:</strong> It seems that the extract induced antispasmodic effect mainly via calcium influx blockade and partially through blocking &beta;-adrenoceptors and nitric oxide (NO) synthesis. However, neither &alpha;-adrenoceptors nor opioid receptors or cGMP synthesis were involved.<br> &nbsp; Rat, Uterus, Physalis alkekengi, Antispasmodic 193 198 http://ijrm.ir/browse.php?a_code=A-10-549-263&slc_lang=en&sid=1 Mohammad Kazem Gharib Naseri Gharibnaseri_m@yahoo.com Yes Physiology Research Center, Department of Physiology, School of Medicine, Ahwaz Jundishapur University of Medical Sciences, Ahwaz, Iran Maryam Mohammadian No Physiology Research Center, Department of Physiology, School of Medicine, Ahwaz Jundishapur University of Medical Sciences, Ahwaz, Iran Zahra Gharib Naseri Pharm No Physiology Research Center, Department of Physiology, School of Medicine, Ahwaz Jundishapur University of Medical Sciences, Ahwaz, Iran