Investigation of the cardiac depressant effect of Caralluma tuberculate N.E.Br on isolated rabbit heart

Abstract

Purpose: To investigate the histopathological and cardiac depressant effect of the aqueous methanol extract of Caralluma tuberculata N.E. Br (AMECT) (family: Asclepiadaceae)’ and to determine if there is a scientific basis for its cardiovascular diseases-related folkloric use. Methods: The effect of AMECT in different concentrations ranging from 0.00001 to 1.0 mg/mL were evaluated in isolated perfused rabbit heart to assess their effect on the force of contraction and heart rate using Langendorff’s apparatus. Atropine and adrenaline were used to identify the underlying mechanism of response produced by AMECT. The extract was studied for its possible mechanism in the absence and presence of atropine and adrenaline. In addition, sub-chronic toxicity and histopathological study of heart tissues in rats were assessed by administering 500 mg/kg of extract. Results: At all concentrations, AMECT produced significant (p < 0.001) negative ionotropic and negative chronotropic effects. The most significant effect was observed at 0.001 mg/mL and higher concentrations hence 0.001 mg/mL was selected for further studies. Pre-incubation with atropine did not significantly inhibit the effects of AMECT. However, AMECT significantly (p < 0.01) blocked the cardiac stimulant effect of adrenaline. In the histopathological studies, AMECT did not produce any significant cellular changes or signs of toxicity in the sub-chronic toxicity study. Conclusion: The cardiac-depressant responses of AMECT may involve the β-adrenergic receptors in the myocardium of isolated rabbit heart thus confirming the rationale for its use in ethnomedicine for cardiac diseases.