ABSTRACT
BACK GROUND: Long-term administration of Nigella sativa showed cardiac hypertrophic and positive inotropic effects. Thymoquinone (TQ) is an active ingredient in Nigella sativa. Therefore, we aimed to test the cardiac effects of long-term TQ administration. MATERIALS AND METHODS: Twenty adult Wistar rats weighing (150-250 g) were divided into two groups: control and TQ. A TQ-olive oil solution was administered orally to the TQ group (dose 10 mg/kg) for two months. An equivalent volume of olive oil was given to the control group. Langendorff isolated hearts were studied. Peak tension, time to peak tension, half relaxation time, and myocardial flow rate were determined. Heart and left ventricle weights and ratios were recorded. RESULTS: The TQ group exhibited significantly higher peak tension than the control group. There were no significant differences between the two groups in time to peak tension, half relaxation time, and myocardial flow rate. Likewise, there were no signs of cardiac hypertrophy. CONCLUSIONS: Long-term administration of oral TQ induced a positive inotropic effect in the form of an increase in peak tension. TQ administration did not result in cardiac hypertrophy or an increased cardiac metabolic demand at the studied dose. TQ may be a promising inotropic agent.
ABSTRACT
OBJECTIVE: To study the effects of two, months Nigella sativa (N. sativa) oral supplementation to normal rats on cardiac haemodynamics in vivo, the ionotropic and chronotropic properties of the isolated hearts in vitro, and the cardiac responsiveness to progressive adrenergic stimulation by isoproterenol. METHODS: The cardiac workload, after 2 months of N. sativa oral supplementation to normal adult rats, was assessed in vivo by measuring the cardiac pressure-rate product (mean arterial blood pressure multiplied by heart rate). Cardiac performance in vitro was evaluated by calculating the tension-rate product (developed peak tension multiplied by heart rate). The cardiac inotropic and chronotropic adrenergic responsiveness of N. sativa supplemented rats were evaluated in a Langendorff heart model upon graded infusion of the beta-adrenergic agonist isoproterenol. RESULTS: The isolated hearts of Nigella-treated rats maintained their normal cardiac adrenergic responsiveness, with a selective enhancement of both the tension-rate product and the inotropic reserve. In contrast, the in vivo cardiac pressure-rate product in N. sativa supplemented rats was not significantly different from the control group. CONCLUSION: The demonstrated favourable results of N. sativa supplementation on the intrinsic cardiac contractile properties without evidence of an increased cardiac work load or energy consumption in vivo makes N. sativa an attractive inotropic agent with an economic haemodynamic profile. Further research is recommended to explore the usefulness of N. sativa in cardiovascular disorders associated with systolic dysfunction.
