Myostimulating effect of sesamum radiatum aqueous leaf extract in isolated Guinea-pig Taenia caeci contractile activity.

This study was carried to examine the effects of the aqueous leaf extract of Sesamum radiatum, a laxative plant on the contractile activity of Taenia caeci, an intestinal smooth muscle. Strips of Taenia caeci were rapidly removed from guinea-pig and were suspended between two L-shaped stainless steel hooks in a 10 ml organ bath with Mac Ewen solution. The isometric contractile force of the Taenia caeci strips were recorded by using a strain gauge. S. radiatum aqueous leaf extract (ESera) is a spasmogenic substance. This myostimulant effect is characterized by the increase of the rhythm and the amplitude of isolated guinea-pig Taenia caeci smooth muscle in normal solution and by the development of contracture in modified solution and in solution without calcium. A similar effect was observed with ACh which caused a graded increase of the contractile activity of Taenia caeci. The effects induced by ESera and ACh were reversed in the presence of atropine. The spasmogenic effect induced by ESera could justify partially the use of S. radiatum as laxative in traditional medicine.

Nitric oxide pathway-mediated relaxant effect of aqueous sesame leaves extract (Sesamum radiatum Schum. & Thonn.) in the guinea-pig isolated aorta smooth muscle.

BACKGROUND: Sesamum radiatum Schum. & Thonn. (Pedaliaceae) is an annual herbaceous plant, which belongs to the family Pedaliaceae and genus Sesamum. Sesame is used in traditional medicine in Africa and Asia for many diseases treatment. Sesame plant especially the leaves, seed and oil are consumed locally as a staple food by subsistence farmers. The study analyses the relaxation induced by the aqueous extract of leaves from sesame (ESera), compared with those of acetylcholine (ACh) in the guinea-pig aortic preparations (GPAPs), in order to confirm the use in traditional medicine for cardiovascular diseases. METHODS: The longitudinal strips of aorta of animals were rapidly removed from animals. The aorta was immediately placed in a Mac Ewen solution. Experiments were performed in preparations with intact endothelium as well as in aortae where the endothelium had been removed. The preparations were suspended between two L-shaped stainless steel hooks in a 10 ml organ bath with Mac Ewen solution. The isometric contractile force of the aorta strips of guinea-pig were recorded by using a strain gauge. All both drugs caused concentration-dependent relaxations responses. RESULTS: The aqueous extract of leaves from sesame ESera (1 x 10(-7) - 0.1 microg/ml) caused a graded relaxation in GPAPs with intact endothelium, with a EC50-value of 1 x 10(-4) microg/ml. The same effect was observed with ACh (7 x 10(-2) nM - 7 x 10(-1) microM), which caused relaxation in a concentration-dependent manner. The relaxation in response to ESera and, like that to ACh in GPAPs without endothelium, was fully abolished. Destruction of the endothelium or incubation with the nitric oxyde synthase inhibitor (L-NNA) significantly enhanced the inhibition of the relaxation response to ESera. Moreover, all concentrations induced vasoconstrictions. However, L-NNA produced a significant displacement to the right (about 65-fold) of the relaxation response to ESera. Similar results were obtained with ACh. Both diclofenac and tetra-ethyl-ammonium (TEA) pretreatment of GPAPs induced a suppression of the relaxation caused by ESera, and produced a very significant rightward shifts of the CRC (16-fold) for diclofenac and increase the Emax. In contract, the relaxation caused by ACh was not significantly affected by diclofenac or by TEA. CONCLUSION: Thus, the present results indicate clearly that the nitric oxide largely contribute to the relaxation effect of Esera and of ACh in GPAPs. In addition, their contractile effects are also mediated by cyclooxygenase activation, and probably the K+ channels involvement, that confirm the use of various preparations of Esera for the treatments of cardiovascular diseases.