Some neuromuscular effects of the crude extracts of the leaves of Abrus precatorius

Some neuromuscular effects of the crude extracts of the leaves of Abrus precatorius were investigated using isolated toad rectus abdominis and rat phrenic nerve-diaphragm muscle preparations as well as young chicks. The ethanol extract of the leaves inhibited acetylcholine-induced contractions of both toad rectus abdominis and rat phrenic nerve-diaphragm muscle preparations. The effects were concentration-dependent and reversible. The extract also caused flaccid paralysis when injected intravenously into young chicks. The ethanol extract had no effect on direct electrical stimulation of rat diaphragm. The inhibitory effect of the ethanol extract on the rat phrenic nerve-diaphragm preparation was potentiated in the presence of reduced calcium ions, elevated magnesium ions, or reduced potassium ions. Thus, the ethanol extract showed a similarity to d-tubocurarine in respect of the pattern of neuromuscular blockade. Both the petroleum ether and the water (cold and hot) extracts had no observable effects on the skeletal muscles used in this project. Apparently, the poisonous neuronal component of the leaves of Abrus precatorius resides mainly in the ethanol extract.