Assessment of the role of nitric oxide component of Falcaria vulgaris extract in coronary vasodilatation in the isolated rat heart

Falcaria vulgaris locally named Paghazah has been used traditionally as a herbal medicine and as a vegetable in the west of Iran. Effects of the plant extract on the isolated rat heart including vasodilatation have been shown in our previous study. The aim of this study was to assess thoroughly the effect of the plant on vasodilatation, role of the nitric oxide as one of the most important mechanisms of vasodilatation, and the potential cytotoxic effect of this herbal medicine on the isolated rat heart.

Hearts of male Wistar rats were isolated and perfused under constant pressure according to Langendorff method. Extract of the plant was prepared by soaking it in 70% ethanol according to percolation method. The rats were assigned into three groups. In one group (n=8) concentrations of 0.2, 1 and 5 microgram/ml of the extract were infused into the hearts over a period of 5 minutes and different cardiac parameters were measured and recorded. In the second group (n=8) 15 mg and 22.5 mg of the extract were used as bolus injections by ten minute intervals. Then the above mentioned doses were injected again into the hearts treated with LNAME (100micmol). In the third group, at first the hearts were treated with LNAME, then 15 mg and 22.5 mg of extract were injected.

Results of this study showed that infusion of concentrations of 0.2, 1 and 5 micgr/ml of the extract significantly increased coronary solution flow (CSF) from the third to the fifth minute after infusion (P<0.05). Following injection of 15 mg and 22.5 mg of extract, CSF increased significantly from 10.58±0.63 and 9.66±0.52 ml/min to 13.76±0.51 and 12.18±0.64 respectively (P<0.05). Also similar significant increases in CSF changes were seen in the presence of LNAME (P<0.05) which indicated nitric oxide played no role in this mechanism. Amount of LDH released after bolus injection of the extract did not significantly differ from its amount in the control group.

In the present study we emphasize that the coronary vasodilator effect of Falcaria vulgaris hydro alcoholic extract in the isolated rat heart is significant. Nitric oxide is not involved in this mechanism. Considering the time and wide range of administrated doses (infusion method) and reversible effect of the extract it can be regarded harmless. Also on the basis of LDH measurement it has no cytotoxic effect. In our study nitric oxide had no role in coronary vasodilatation. Therefore evaluation of other mechanisms of vasodilatation brought into play by the extract is recommended.