Studies On Blood Pressure Regulation And Mechanism Of Apocynum Venetum

Apocynum tea as experimental material and SHR as experimental animals, the effect and mechanism of blood pressure regulation of Apocynum venetum was studied. The results showed that the aqueous extracts of Apocynum venetum induced antihypertensive effect in SHR and the time-effect curve showed first increased then decreased characteristics. However, the antihypertensive effect of Apocynum venetum was slow and the first increased then decreased curve wasn’t significant until the third week. Five hours after administration, the antihypertensive effect could be observed and till 8 hours the system blood pressure was lowest. Chronic antihypertensive experiment for 6 weeks showed Apocynum venetum could induce antihypertensive effect slowly. The significant and stable decrease, about 15 mmHg, of system blood pressure was showed after three weeks. Meanwhile, Apocynum yenetum treatment for 6 weeks, no significant effect on SHR’s heart rate and blood fat, etc, had been showed, but significant diuretic effect, and urinary Na+, K+, Cl" increase had been showed. Therefore, this result showed that the antihypertensive effect of Apocynum venetum might be throught its diuretic mechanism.Apocynum venetum leaves as experimental material and wistar rats as experimental animals, the acute diuretic activity of Apocynum venetum was investigated. The results showed that in the case of urinary load, the aqueous extract of Apocynum venetum could promote the secretion of rats’urine and the urine output was increased significantly after 6 or 8 hours after oral administration. Meanwhile, the secretion of K+、Na+、Cl-were also increased with increasing doses. The time of diuretic was coinfident with that of antihypertensive phase and indicated that the antihypertensive effect of Apocynum venetum might be throught its diuretic mechanism.Using the traditional method, the effective fractions were isolated and 6 fractions were achieved, including ethanol extract fraction (EF), ethanol residue fraction (ER), n-hexane fraction (nHF), ethyl acetate fraction (EAF), n-butanol fraction (nBF) and parts of the water fraction (WF). Six fractions as experimental material and wistar rats as experimental animals, the acute diuretic activity of Apocynum venetum was studied. The result showed that the EF played a major role in promoting the urine and urine electrolytes K+, Na+, Cl’secretion in wistar rats. Among them, the nBF isolated from EF played a major role in promoting the urine secretion and urine Na+ secretion, while the WF isolated from EF played a major role in promoting the urine secretion and urine K+ and Cl- secretion.By correlation analysis, total phenols and total flavonoids of Apocynum venetum and diuretic index showed a significant positive correlation (r= 0.886, p< 0.01; r= 0.882, p< 0.01), respectivly. Among them, isoquercitrin (r=0.747, p<0.01), hyperoside (r=0.758, p< 0.01), rutin (r=0.793, p< 0.01) and chlorogenic acid (r=0.650, p< 0.05) were all showed a significant positive correlation with diuretic index, respectivly Therefore, Apocynum venetum maight be mainly through the interaction of isoquercitrin, hyperoside, rutin and chlorogenic acid and other flavonoids or polyphenol to promote urine secretion, then to decreased the blood pressure of wistar rats.In addition, not only the six weeks of chronic blood pressure regulating experiment but also the acute toxicity experiment showed no toxic effects on the rats.This experiment can provide the experimental basis for the studies of the separation of antihypertisive component, the interaction between the components and its mechanism of Apocynum venetum and it can also provide experimental basis for the development, use and intensive processing of Apocynum venetum as antihypertisive health food.