Cardiovascular effects of Teucrium polium L. extract in rabbit

Background: Teucrium polium L. (TP) have been used in herbal medicine for different purposes such as antispasmodic, antidiabetic and lowering blood lipid. In the present study, the impact of aqueous-ethanol extract of TP on blood pressure, heart rate and intraventricular pressure was investigated in rabbit. Materials and Methods: Twenty-four NWZ rabbits weighed (2-3 kg) were randomly divided into four groups. In each experiment, two groups of six rabbits received jugular injection of either TP extract (20, 40 and 80 mg/kg) or normal saline for blood pressure effects and two groups for intraventricular pressure. Then, blood pressure, heart rate and intraventricular pressure were measured via carotid cannula using pressure transducer connected to a power lab system, and the data were pooled from independent, single-blinded experiments for each group. Results: Treatment with 80 mg/kg of TP extract significantly depressed the mean arterial blood pressure (12.5%, P< 0.05). However, there was no significant decrease in the 20 or 40 mg/kg dose or normal saline treatment group. Moreover, the extract increased (dp/dt)max (P<0.05), maximum left ventricular pressure (LVP_max) (P<0.05) and decreased (dp/dt)min significantly (P<0.05), there was no meaningful effect on left ventricular end-diastolic pressure (LVEDP). Conclusion : The present results demonstrated the extract had no effect on the heart rate, but showed a positive inotropic on the heart and hypotensive effects. These data suggested that hypotensive effect may counterbalance by the inotropic effect of the extract.