Effects of Mondia whitei extracts on the contractile responses of isolated rat vas deferens to potassium chloride and adrenaline

Objective: To investigate the effects of the methylene chloride:methanol (CH 2 Cl 2 :MeOH, Animal Physiology and 1:1) extract of the dried roots of Mondia whitei Linn and its hexane and methanol fractions on Phytopharmacology potassium chloride (KCl) and adrenaline (Adr)-induced contractions of rat vas deferens. Laboratory, Faculty of Science, Materials and Methods: Isolated strips of normal adult rat vas deferens were mounted in University of Dschang, Box 67 a Ugo Basile single-organ bath containing Krebs solution. Cumulative concentration-response Dschang, Cameroon. curves of KCl (1–7 x 10 M) and adrenaline (1.21–8.45 x 10 M) were established in the Department of Chemistry, absence and presence of M. whitei (50–400 μg/ml). In separate experiments, after obtaining a Faculty of Science, University stable plateau of contractions with KCl (60 mM), M. whitei samples (50–400 μg/ml) were of Yaounde I, Box 812, Yaounde, Cameroon. added cumulatively to relax the preparation. In KCl (60 mM), containing depolarizing me­ Animal Physiology Laboratory, dium, cumulative concentration-contraction curve to CaCl2 (2–14 x 10 -2 M) was elicited in the Faculty of Science, University absence and presence of the hexane fraction of M. whitei (50–400 μg/ml). of Yaounde I, Box 812, Results: All the M. whitei samples produced rightward shift of the concentration-response Yaounde, Cameroon. curves to KCl and Adr. At high concentration of the plant extracts (400 μg/ml), a decrease of the maximal response to the contractile agents was observed compared with that obtained Received: 5.6.2004 with the control. All the three extracts produced concentration-dependent relaxation of the Revised: 13.9.2005 plateau of contraction induced by KCl and the hexane fraction appeared to be the more Accepted: 28.10.2005 potent. In calcium-free physiological salt solution, the hexane fraction of M. whitei produced Correspondence to: rightward shift to the concentration-response curve to CaCl2 and completely abolished the Pierre Watcho contractile effect of calcium at high concentration (400 μg/ml). E-mail: [email protected] Conclusion: It is concluded that M. whitei extracts antagonized the contractile responses to KCl and Adr in isolated rat vas deferens, which could be due to the blockade of voltage­ operated calcium channels.