Methanol extract of Tephrosia vogelii leaves potentiates the contractile action of acetylcholine on isolated rabbit jejunum

To investigate the modulating role of methanol extract of Tephrosia vogelii leaves on acetylcholine (ACh)-induced contraction of isolated rabbit jejunum. Rabbit jejunum segment was removed and placed in an organ bath containing Tyrode's solution, and its contractions were recorded isometrically. ACh (2.0 × 10−10 g/mL) and the extract (2.0 × 10−4 g/mL) individually increased the frequency of contraction (mean ± SEM) of the isolated smooth muscle tissue by 47.6% ± 9.5% and 77.8% ± 66.5%, respectively. When ACh and the extract were combined, the frequency of contraction of the tissue was increased by 222.2% ± 25.9%, representing a 366.7%-increase (P < 0.001) over the effect of ACh alone. Similarly, ACh (2.0 × 10−9 g/mL) and the extract individually increased significantly (P < 0.001) the amplitude of contraction of the tissue by 685.7% ± 61.1% and 455.2% ± 38.1%, respectively. When ACh and the extract were combined, the amplitude of contraction of the tissue rose by 1 263.8% ± 69.0%, representing 84.3% increase over the effect of ACh alone. The findings demonstrate that methanol extract of Tephrosia vogelii leaves potentiates the contractile effect of ACh on intestinal smooth muscle, supporting the traditional claim that the plant is purgative.