PHARMACOLOGICAL STUDIES ON CHINESE RAUWOLFIA,Ⅱ.THE HYPOTENSIVE EFFECT AND TOXICITY OF RAUWOLFIA COLLECTED FROM HAINANDAO

The rauwolfia plant growing on Hainandao has been identified to be also Rauwolfia verticillata (Lour.) Baill. The leaves and roots collected from that island were studied for hypotensive effect and toxicity. A crude extract of the leaves, the alkaloid, of leaves and roots, when injected intravenously at respective dosages of 50—200 mg (leaves)/kg, 3 mg/kg and 0.5—1 mg/kg produced remarkable and sustained drop of the blood pressure of anesthetized dogs. The pulse rate slowed down, the respiratory rate increased; and the intestinal tone increased. The pressor effect of adrenaline became potentiated. No tachyphylaxis appeared on repeated injection. All the hypertensive dogs, 9 treated with the crude extract of leaves at a daily dose of 4 g (leaves)/kg, 4 treated with the alkaloid of leaves at 20—40 mg/kg/day, and 3 treated with the alkaloid, of roots at 2—10 mg/kg, by oral route, showed remarkable fall of blood pressure. The pulse rate of most animals decreased. Sedation, pupil constriction, nictitating membrane relaxation and drop of eye-lids were also shown by most of the treated animals. Some showed also tremors and some others had soft stools. Among the preparations studied the alkaloid of leaves gave much less symptoms than the others. Nine hypertensive rats receiving a daily oral dose of 40—80 mg/kg also showed significant drop of blood pressure. The LD₅₀ in mice has been found to be 74±2.5 g (leaves)/kg, 2.35±0.1 g/kg and 0.82±0.005 g/kg respectively for the crude extract of leaves and the alkaloid of leaves and roots, given by gastric tube. No effect on the growth of mice was found in subacute toxicity tests. The alkaloid of both leaves and roots did not affect the liver and kidney function, electrocardiogram, blood and urine components of dogs, but the crude extract of leaves appeared to produce some damage to the liver and kidney.