TOXICOLOGICAL EVALUATION OF NERIUM OLEANDER ON ISOLATED PREPARATIONS

In vitro toxicological evaluation of Nerium oleander was carried out u sing different isolated preparations. The methanolic leaf extract pote ntiated both spontaneous and electrically evoked contractions of vas d eferens of rats and guinea-pig ileum in a concentration dependent mann er. The effect was not antagonized by the adrenergic blocker, tolazoli ne. The extract inhibited electrically stimulated neurogenic twitch re sponses of rat phrenic nerve diaphragm preparation. The dose dependent inhibition of twitch response in this preparation could not be revers ed by the anticholinesterase drug, neostigmine. The extract evoked a p ersistent depolarizing effect on the phrenic nerve diaphragm preparati on. The extract exhibited its most potent action on the isolated right atrial preparation of rat. It inhibited the rate of spontaneously bea ting atria in a concentration dependent manner. The negative chronotro pic effect was not antagonized either by antimuscarinic drug or adrene rgic agonist.