Cardiovascular effects of Teucrium polium L. extract in rabbit

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.

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.

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).

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.