The ex vivo activity of the ethanol root extract of Senna occidentalis (Labaceae) on the isolated rat uterus was examined in order to determine its potential usefulness in the therapy of uterine related pathologies.
The ethanol root extract of S. occidentalis was investigated on the isolated uterus of rats primed with diethylstilboestrol (0.1 mg/kg) 24 h prior to the experiment. The extract (2.5 and 7.5 mg/mL) effect on ACh (0.1 1.0 µg/mL) induced contractility, in the presence of atropine (0.12 µg/mL), propranolol (8 μg/mL), CaCl2 (in Ca2+-free medium) and in the presence of high KCl (100 mM) was examined.
The extract significantly inhibited ACh-induced uterine contractions (P < 0.05) and CaCl2-induced uterine contractions (in Ca2+-free medium) (P < 0.05) in a non-competitive but concentration-dependent manner. A rightward shift of the concentration-response curve was observed in all cases. However, a bell- shaped concentration-response curve was observed for CaCl2. The inhibitory effect of the extract on ACh-induced uterine contractions was unaffected by propranolol. The extract (0.1 -0.4 mg/mL) also inhibited high KCl- induced uterine contractions.
In conclusion, the root extract of S. occidentalis has been shown to inhibit agonist-induced uterine contractions potentially through interaction with voltage-operated calcium channels.
Key words: Acetylch‾ Calcium; Propranolol; Ex vivo uterine activity; Senna occidentalis; Uterus
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