Search Results

BACKGROUND: The water extract of white mulberry root-bark plays certain roles in decreasing the blood glucose and blood lipids of rats, antagonizing inflammation and analgesia, relieving asthma and inducing diuresis,as well as relaxing the smooth muscle.OBJECTIVE: To analyze the hypoxic tolerance of white mulberry rootbark by using the hypoxic tolerance test under normal pressure, rapid head-cut test and the test of isoproterenol in enhancing myocardial oxygen consumption.DESIGN: A randomized control study.SETTING: Department of Pathology and Department of Pharmacology,School of Basic Medical Sciences, Gannan Medical College.MATERIALS: The experiments were conducted in the laboratory of the Scientific Research Center of Gannan Medical College between May and June in 2003. Totally 106 healthy adult Kunming mice were used in the following three independent experiments. The white mulberry root-bark extract was provided by the Department of Pharmacology of Gannan Medical College, injection of propranolole hydrochloride by Beijing Pharmaceutical Factory.METHODS: ① Hypoxic tolerance test under normal pressure: Forty mice were divided into four groups with 10 mice in each group according to the method of random number table: saline group, propranolol group, white mulberry root-bark extract groups treated with 0.10 and 0.20 mL/g respectively, and the mice were treated with intraperitoneal injection of saline (0.02 mg/g), propranolol (10 g/L), white mulberry root-bark extract (0.10 and 0.20 mL/g) respectively. After 15 minutes,the mice in the groups were placed into the enclosed 250mL ground and wide mouthed bottles separately, and the survival time of the mice was observed by taking the last breath as the index. ② Rapid headcut test: Thirty mice were divided into three groups with 10 mice in each group according to the method of random number table: saline group, white mulberry root-bark extract groups treated with 0.10 and 0.20 mL/g respectively, and the mice were treated with intraperitoneal injection of saline (0.02 mg/g), white mulberry root-bark extract (0.10and 0.20 mL/g) respectively. After 15 minutes, the heads of the mice were rapidly cut down without anesthesia, and the time from cutting head to the last breath was recorded. ③ Test of isoproterenol in enhancing myocardial oxygen consumption: Thirty-six mice were divided into three groups with 12 mice in each group according to the method of random number table: saline group, isoproterenol group and white mulberry root-bark extract group treated with 0.10 mL/g. In the saline group, the mice were injected with saline subcutaneously (0.03 mL/g),and then intraperitoneally (0.02 mL/g) after 5 minutes. In the isoproterenol group, the mice were firstly treated with subcutaneous injection of isoproterenol (0.015 mg/g), and the intraperitoneal injection of saline (0.02 mL/g) was given after 5 minutes. In the white mulberry root-bark extract group treated with 0.10 mL/g, the mice were firstly injected subcutaneously with isoproterenol (0.015 mg/g), and then injected intraperitoneally with white mulberry root-bark extract (0.01 mL/g)was given after 5 minutes. After 15 minutes, the mice were placed into the enclosed wide mouthed bottles separately, and the survival time of the mice was observed.MAIN OUTCOME MEASURES: The survival time of mice in each group was observed in the three independent experiments.RESULTS: All the 106 healthy adult Kunming mice were involved in the analysis of results. ① Effect of white mulberry root-bark extract on the survival time of mice in the condition of hypoxic tolerance under normal pressure: As compared with the saline group, the survival times in the propranolol group and white mulberry root-bark extract groups treated with0.10 and 0.20 mL/g were obviously prolonged [(36.2±4.3), (81.0±17.0), (66.4±8.9), (90.3±7.4) minutes, t=3.358-3.617,P ＜ 0.01]. ② Effect of white mulberry root-bark extract on the survival time of mice under the condition of cerebral ischemia: As compared with the saline group, the times from cutting head to the last breath in the white mulberry root-bark extract groups treated with 0.10 and 0.20 mL/g were obviously prolonged [(17.8±1.3), (21.2±0.8), (23.5±0.7) minutes, t=2.824-3.432, P ＜ 0.05 or 0.01]. ③ Effect of white mulberry root-bark extract on the survival time of mice under the condition of myocardial oxygen consumption enhanced by isoproterenol: As compared with the saline group, the survival time in the isoproterenol group was obviously shortened, but those in the white mulberry rootbark extract groups treated with 0.10 and 0.20 mL/g were markedly prolonged [(36.2±4.3), (27.9±2.6), (50.6±3.4) minutes, t=2.734-3.035, P ＜ 0.05].CONCLUSION: White mulberry root-bark extract has obvious effect on hypoxic tolerance.