Effect of the volatile oil of Nigella sativa on the arterial blood pressure and heart rate of the Guinea-Pig

ABSTRACT

The effects of the volatile oil [V.O.] of the black seed-Nigella sativa Linn, and its constituent thymoquinon [T.Q.] were examined on the arterial blood pressure and the heart rate of urethane-anaesthetized guinea-pigs. Intravenous administration of the V.O. [30-120 micro 1 kg-1] decreased the arterial blood pressure and the heart rate in a dose-depended manner. Similarly, administration of T.Q.[6-24mg kg -1] decreased the arterial blood pressure and the heart rate. Pretreatment of the animals with atropine or cyproheptadine [2 mg kg -1 for 5 min] or with hexamethonium [10 mg kg -1 for 10 min] antagonized V.O. and T.Q.- induced cardiovscular depressant effects. V.O-induced cardiovascular depressant effects were also significantly antagonized by spinal pithing.it was concluded that V.O.-induced effects were probably due to its constituent T.Q. and were probably mediated centrally within the medulla ablongata via activation of 5-hydroxytrptaminergic and muscarinic mechanisms