Effect of Ethanol Extract of Paulinia pinnata Leaves on the Blood Pressure of Cats

The effect of ethanol extract of the leaves of Paulinia pinnata was investigated on the blood pressure (BP) of normotensive adult cats. The LD50 value of the extract was first determined to ascertain its safety margin. LD50 value of 1190mg/kg, ED50 of 750mg/kg and therapeutic index of 1.85 suggest that the extract can be very toxic at higher doses. For the BP work, the cats were anaesthetized with pentobarbitone 40mg/kg via the intra peritoneal (IP) route. The femoral vein was cannulated for drug administration and carotid artery for blood pressure measurement. All drugs were dissolved in normal saline. On the anaesthetized cats, the ethanol extract of Paulinia pinnata leaves lowered the mean arterial blood pressure (MABP) by 74.9mmHg at a dose of 1.33 x 10-2 mg/kg. The lowering effect compared favourable with those of standard drugs (Acetylcholine and Histamine), which lowered MABP by 97.5 mmHg and 124.6mmHg respectively at the same dose of 1.33 x10-4 mg/kg. The MABP lowering effect of the extract was appreciably blocked by a muscarinic antagonist (Atropine) and histaminergic antagonist (Promethazine), which suggests that the MABP lowering effect of the extract could have been achieved by binding to the numerous muscarinic and histaminergic receptors in the cardiovascular system. Thus, this experiment is suggestive of the mechanism of action of the extract.