Hypoglycemic effect of the total flavonoid fraction from Folium Eriobotryae

The antidiabetic effect of the total flavonoids fraction from leaves of Eriobotrya japonica (EJF) was evaluated through normal and streptozotocin-induced diabetic mice with graded oral doses of 150, 300, 450 mg/kg for 7 days or 14 days. The result showed that the dose of 300 mg/kg and 450 mg/kg resulted significant hypoglycemic effect on normal mice, the dose of 300 mg/kg induced significant decrease in plasma glucose concentration (PGC), glycosylated serum protein (GSP), total cholesterol (TC) and triglyceride (TG), and significant increase in superoxide dismutase (SOD) activity and serum insulin level in streptozotocin-diabetic mice. These results suggested that EJF has hypoglycemic potential.     

Antihypertensive effect of low ethanol intake in spontaneously hypertensive rats

Light to moderate drinking in humans lowers the risk of coronary heart disease and may lower blood pressure. We examined the effect of chronic low daily alcohol consumption on blood pressure, platelet cytosolic free calcium [Ca²⁺]_i, tissue aldehyde conjugates and renal vascular changes in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). We also examined the effects of the same weekly amount of alcohol consumption over a one day period each week simulating weekend drinking in humans. Animals, age 7 weeks, were divided into six groups of six animals each and were treated as follows: WKY and SHR control, normal drinking water; WKY and SHR, 0.5% ethanol in drinking water; WKY and SHR, 3.5% ethanol in drinking water one day/week. After 14 weeks systolic blood pressure, platelet [Ca²⁺]_i, liver, kidney and aortic aldehyde conjugates were significantly higher (p < 0.05) in untreated SHRs as compared to untreated WKYs. Daily 0.5% ethanol consumption in SHRs significantly (p < 0.05) attenuated these changes and also attenuated smooth muscle cell hyperplasia and narrowing of the lumen in small arteries and arterioles of the kidney. WKY rats treated with 0.5% ethanol had lower aldehyde conjugates without any significant effect on blood pressure and platelet [Ca²⁺]_i as compared to WKY controls. Consumption of 3.5% ethanol one day/week did not affect blood pressure and associated changes in normotensive WKY rats or hypertensive SHRs as compared to their respective controls. These results suggest that chronic daily low ethanol intake lowers blood pressure in SHRs by lowering tissue aldehyde conjugates and cytosolic free calcium.     

Antihypertensive effect of tryptic hydrolysate of milk casein in spontaneously hypertensive rats

1. Repeated oral administrations of tryptic hydrolysate of bovine milk casein (CEI) showed antihypertensive effect in spontaneously hypertensive rats. 2. Single oral administration of CEI antagonized the pressor response to angiotensin I. 3. Bovine milk casein hydrolysate inhibited the angiotensin I-converting enzyme (ACE) activity. Three peptides with ACE-inhibiting activity were isolated from CEI. 4. It is suggested that ACE-inhibiting peptides in the tryptic hydrolysate milk casein are absorbed from the intestinal tract and produce an antihypertensive effect.     

Antihypertensive effect of an extract of Passiflora edulis rind in spontaneously hypertensive rats

Orally administered methanol extract of Passiflora edulis rind (10 mg/kg or 50 mg/kg) or luteolin (50 mg/kg), which is one of consistent polyphenols of the extract, significantly lowered systolic blood pressure in spontaneously hypertensive rats (SHRs). Quantitative analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) showed that the extract contained 20 microg/g dry weight of luteolin and 41 microg/g dry weight of luteolin-6-C-glucoside. It also contained gamma-aminobutyric acid (GABA, 2.4 mg/g dry weight by LC-MS/MS or 4.4 mg/g dry weight by amino acid analysis) which has been reported to be an antihypertensive material. Since the extract contained a relatively high concentration of GABA, the antihypertensive effect of the extract in SHRs might be due mostly to the GABA-induced antihypertensive effect and partially to the vasodilatory effect of polyphenols including luteolin.     

Antihypertensive effect of gamma-amino butyric acid enriched soy products in spontaneously hypertensive rats

The effect of gamma-amino butyric acid (GABA)-enriched soybean on blood pressure was investigated in male spontaneously hypertensive rats. Ten-week-old rats were given diets containing graded levels of GABA-enriched soybean powder for 8 weeks. The systolic blood pressure in rats fed 0.15% GABA diet was significantly lower at 1st week and maintained lower values for 4 weeks as compared with 0% GABA controls. No effect on blood pressure was found in those of 0.03 and 0.3% GABA. The results suggest that there exist appropriate dietary GABA level to get the blood pressure lowering effect.     

降血压乳酸菌发酵乳对原发性高血压大鼠的降压效果

目的对具有血管紧张素转化酶(ACE)抑制活性的乳酸菌DM9057发酵乳的抗胃肠道酶解能力及原发性高血压大鼠(SHR)体内降压效果进行研究。方法以10 ml/kg和2.5 ml/kg发酵乳一次性和连续灌胃原发性高血压大鼠。结果 DM9057发酵乳具有较好的抗胃肠道酶能力,并且2个剂量均具有较好的降血压效果,其中以10 ml/kg剂量效果最为显著,一次性和连续灌胃后,最大降压值为(17.97±3.82)、(25.46±5.06)mmHg。结论乳酸菌DM9057发酵乳具有较强的抗胃肠道能力,同时在原发性高血压大鼠体内能够发挥一定的降血压作用。     

扁茎黄芪同源四倍体的诱导

以扁茎黄芪的干燥成熟种子为试验材料,用0．1％、0．3％和0．5％的秋水仙碱溶液分别浸泡种子24h、48h、72h和96h来诱导同源四倍体,并对诱导处理后获得的再生植株进行染色体鉴定,得出以0．3％秋水仙碱溶液浸泡72h为诱导同源四倍体的最佳处理组合。     

Antihypertensive effects of onion on NO synthase inhibitor-induced hypertensive rats and spontaneously hypertensive rats

This study was designed to show the effects of onion on blood pressure in N(G)-nitro-L-arginine methyl ester (L-NAME) induced-hypertensive rats and stroke prone spontaneously hypertensive rats (SHRSP) using dried onion at 5% in their diets. For the experiment with L-NAME induced-hypertensive rats, male 6-weeks-old Sprague-Dawley rats were given tap water containing L-NAME to deliver 50 mg/kg BW/day. In this experiment, we found distinct antihypertensive effects of onion on the L-NAME induced-hypertensive rats and the SHRSP. Dietary onion decreased the thiobarbituric acid reactive substances (TBARS) in plasma in these hypertensive rats. Also, onion increased the nitrate/nitrite (products of nitric oxide (NO)) excreted in urine and the NO synthase (NOS) activity in the kidneys in SHRSP. These results suggested that the increased NO caused by the greater NOS activity, and additionally by the increased saving of NO by the antioxidative activity of onion, was one of the cause of the antihypertensive effect of onion in SHRSP. In the L-NAME induced hypertensive rats, onion did not significantly block the inhibition of NOS activity by L-NAME, and decreased nitrate/nitrite excretion in urine was not restored. The mechanism of the antihypertensive effect of onion probably involves increased saving of NO by antioxidative activity of onion in L-NAME induced-hypertensive rats.     

Antihypertensive effects of vanadium compounds in hyperinsulinemic,hypertensive rats

Although considerable evidence lends credence to the association between insulin resistance, hyperinsulinemia and essential hypertension, the precise nature of this relationship remains unexplained. In the present investigation, we examined the proposition that these metabolic defects contribute causally to the development of high blood pressure. If these metabolic abnormalities were responsible for the development of hypertension, then drug interventions that improve these defects should also decrease high blood pressure. Since previous studies have demonstrated that vanadium compounds enhance insulin action and lower plasma insulin levels in nondiabetic rats, we examined the effects of these compounds on insulin sensitivity, plasma insulin concentration and blood pressure in two hyperinsulinemic models of experimental hypertension. The animal models studied were the genetically predisposed spontaneously hypertensive rat and the fructose-hypertensive rat, where hypertension is induced in normotensive rats by feeding them a high fructose diet. Vanadium compounds caused marked and sustained decreases in plasma insulin concentration and blood pressure in both the animal models studied. Furthermore, the effect of the drugs on blood pressure was reversed by restoring plasma insulin levels in the drug-treated rats to those observed in their untreated counterparts. These data suggest that either hyperinsulinemia contributes to the development of hypertension in both the spontaneously hypertensive and the fructose-hypertensive rats or that the underlying mechanism is closely related to the expression of both these disorders.     

微分脉冲伏安法测定沙苑子中鼠李柠檬素类黄酮含量

在 0 .0 5 m ol/ L 硫酸铵溶液中 ,采用微分脉冲伏安法 ,测定沙苑子中鼠李柠檬素类黄酮含量。灵敏度达 10 - 6mol/ L,在 6 .10× 10 - 6～ 3.0 5× 10 - 5m ol/ L 浓度范围内峰电流与沙苑子苷浓度成线性关系 (r=0 .995 9) ,回收率达96 .9%～ 10 3.0 % (RSD=2 .5 4 % ,n=6 )。结果表明 ,可不经分离直接测定沙苑子提取液中鼠李柠檬素类黄酮的含量     

以沙苑子苷为对照品测定沙苑子总黄酮含量

目的 :以沙苑子苷为对照品测定沙苑子总黄酮含量。方法 :80 %乙醇提取液 ,2 6 6nm测定紫外吸收度。结果 :总黄酮含量为 2 1.5mg/g ,RSD =1.0 0 % ;回收率 95 .4 % ,RSD =2 .2 7% ,线性范围 4～ 2 4ug/ml。结论 :本法测定沙苑子总黄酮含量 ,操作简便 ,稳定性好 ,可用于沙苑子的质量控制。     

Antihypertensive treatment in spontaneously hypertensive rats with streptozotocin-induced diabetes mellitus

Recent clinical reports have suggested that hypertension accelerates the progress of diabetic nephropathy and retinopathy, whereas antihypertensive treatments may retard them. Thus, the effect of antihypertensive treatment in diabetes mellitus with hypertension was evaluated in rats. A model of diabetes mellitus with hypertension has been developed in spontaneously hypertensive (SHR) rats by unilateral nephrectomy and streptozotocin (STZ, 30 mg/kg, i.v. treatment). The rats were treated with four antihypertensive drugs orally for 12 weeks thereafter. STZ treatment induced chronic hypeglycaemia (300-400 mg/dl), decreased body weight and heart rate, and caused vascular changes of ophthalmic fundi and cataracta. The kidney of these rats showed proliferative changes such as periarteritis nodosa, hyperplasia, or fibronecrosis of the arterioles, exudative changes, mesangial proliferation, or thickening of the basement membrane of the glomeruli. Enalapril (10 mg/kg per day) and remipril (Hoe 498) (1 mg/kg per day), converting enzyme inhibitors, or arotinolol (20 mg/kg per day), a beta-adrenoceptor blocking drug, decreased blood pressure, prevented the development of renal and ocular lesions, and tended to increase creatinine clearance. Nisoldipine (3 mg/kg per day), a calcium-entry blocking drug, tended to decrease blood glucose, and prevented the decrease of body weight and development of ocular lesions. In conclusion, antihypertensive treatments were effective in preventing the progress of diabetic retinopathy and nephropathy, and renal insufficiency in this animal model.     

沙苑子的化学成分和药理作用

沙苑子主要含有黄酮类、三萜类、有机酸类、氨基酸、多肽、蛋白质、鞣质、甾醇、微量元素等。具有改善血液流变学指标、降低血压、调节血脂、抑制血小板聚集、保护肝脏、增强免疫功能、抗炎、镇痛及调节中枢神经系统等作用。     

Antihypertensive effect of angiotensin I-converting enzyme inhibitory peptides from a sesame protein hydrolysate in spontaneously hypertensive rats

Sesame peptide powder (SPP) exhibited angiotensin I-converting enzyme (ACE) inhibitory activity, and significantly and temporarily decreased the systolic blood pressure (SBP) in spontaneously hypertensive rats (SHRs) by a single administration (1 and 10 mg/kg). Six peptide ACE inhibitors were isolated and identified from SPP. The representative peptides, Leu-Val-Tyr, Leu-Gln-Pro and Leu-Lys-Tyr, could competitively inhibit ACE activity at respective Ki values of 0.92 microM, 0.50 microM, and 0.48 microM. A reconstituted sesame peptide mixture of Leu-Ser-Ala, Leu-Gln-Pro, Leu-Lys-Tyr, Ile-Val-Tyr, Val-Ile-Tyr, Leu-Val-Tyr, and Met-Leu-Pro-Ala-Tyr according to their content ratio in SPP showed a strong antihypertensive effect on SHR at doses of 3.63 and 36.3 microg/kg, which accounted for more than 70% of the corresponding dosage for the SPP-induced hypotensive effect. Repeated oral administration of SPP also lowered both SBP and the aortic ACE activity in SHR. These results demonstrate that SPP would be a beneficial ingredient for preventing and providing therapy against hypertension and its related diseases.     

Antihypertensive treatment differentially affects vascular sphingolipid biology in spontaneously hypertensive rats

Background

We have previously shown that essential hypertension in humans and spontaneously hypertensive rats (SHR), is associated with increased levels of ceramide and marked alterations in sphingolipid biology. Pharmacological elevation of ceramide in isolated carotid arteries of SHR leads to vasoconstriction via a calcium-independent phospholipase A₂, cyclooxygenase-1 and thromboxane synthase-dependent release of thromboxane A₂. This phenomenon is almost absent in vessels from normotensive Wistar Kyoto (WKY) rats. Here we investigated whether lowering of blood pressure can reverse elevated ceramide levels and reduce ceramide-mediated contractions in SHR.

Methods and Findings

For this purpose SHR were treated for 4 weeks with the angiotensin II type 1 receptor antagonist losartan or the vasodilator hydralazine. Both drugs decreased blood pressure equally (SBP untreated SHR: 191±7 mmHg, losartan: 125±5 mmHg and hydralazine: 113±14 mmHg). The blood pressure lowering was associated with a 20–25% reduction in vascular ceramide levels and improved endothelial function of isolated carotid arteries in both groups. Interestingly, losartan, but not hydralazine treatment, markedly reduced sphingomyelinase-induced contractions. While both drugs lowered cyclooxygenase-1 expression, only losartan and not hydralazine, reduced the endothelial expression of calcium-independent phospholipase A₂. The latter finding may explain the effect of losartan treatment on sphingomyelinase-induced vascular contraction.

Conclusion

In summary, this study corroborates the importance of sphingolipid biology in blood pressure control and specifically shows that blood pressure lowering reduces vascular ceramide levels in SHR and that losartan treatment, but not blood pressure lowering per se, reduces ceramide-mediated arterial contractions.     

Antihypertensive effects of acetic acid and vinegar on spontaneously hypertensive rats

To clarify the possibility of a preventive effect of dietary vinegar on blood pressure, long-term administration of vinegar or the acetic acid to SHR was examined. As a result, it was observed that acetic acid itself, the main component of vinegar, significantly reduced both blood pressure (p<0.05) and renin activity (p<0.01) compared to controls given no acetic acid or vinegar, as well as vinegar. There were no significant differences in angiotensin I-converting enzyme activity in various organs. As for the mechanism of this function, it was suggested that this reduction in blood pressure may be caused by the significant reduction in renin activity and the subsequent decrease in angiotensin II. From this study, it was also suggested that the antihypertensive effect of vinegar is mainly due to the acetic acid in it.     

气相色谱-质谱法测定中药沙苑子中的氨基酸

本文利用气相色谱一质谱(GC/MS)联用技术首次对中药沙苑子中的氨基酸进行了定性定量分析。沙苑子经盐酸水解后,对其氨基酸水解液进行羟基脂化和氨基酰化的衍生化反应,利用GC/MS法共测得15种氨基酸,由外标法测定了每种氨基酸的含量。由此得出沙苑子中氨基酸的总质量分数为4.23％。     

Antihypertensive effects of Dorstenia psilurus extract in fructose-fed hyperinsulinemic, hypertensive rats.

We examined the effect of methanol/methylene chloride extract of Dorstenia psilurus given by gastric intubation on systolic blood pressure, plasma glucose, insulin, cholesterol, triglycerides and creatinine in rats with fructose-induced hypertension. Male Wistar rats in groups of 6 animals each were fed fructose-rich diets or standard chow for 3 weeks and treated with 100 mg/kg/day or 200 mg/kg/day of plant extract or vehicle for 3 subsequent weeks. Systolic blood pressure was measured every three days using the indirect tail cuff method. Systolic blood pressure was higher in fructose-fed rats (142+/-2 mm Hg, p < 0.01) compared with the controls (112+/-2 mm Hg), and was lower in Dorstenia psilurus-treated groups (127+/-2 and 119+/-1 mm Hg for the dose of 100 and 200 mg/kg, respectively) compared with the fructose-fed rats. Plasma insulin, cholesterol and triglycerides were higher on the fructose-rich diet compared with the controls. Plasma insulin and cholesterol were lower in the Dorstenia psilurus-treated groups. These results suggest that, Dorstenia psilurus treatment could prevent and reverse high blood pressure induced by a diet rich in fructose probably by improvement of plasma insulin levels. The plant extract might prove useful in the treatment and/or prevention of hypertension.     

Antihypertensive effect of passion fruit peel extract and its major bioactive components following acute supplementation in spontaneously hypertensive rats

Extracts from leaves, peels or flowers of Passiflora are noted for their medicinal effects. Passiflora edulis peel extract (PFPE) has been proposed to lower blood pressure (BP); however, only indirect measurement techniques have been employed. To more accurately measure the effect of PFPE on hemodynamic parameters and determine the minimal effective dose, hemodynamic parameters were directly measured in spontaneously hypertensive rats (SHR) implanted with radiotelemeters. PFPE was given orally at 0, 2.5, 50 or 200 mg/kg body weight (BW) to determine the minimal effective dose. Once this dose was determined, the potential active components, edulilic acid (EA), anthocyanin fraction (AF) or γ-aminobutyric acid (GABA), were tested to determine which may contribute to the reductions in BP. The 50 mg PFPE/kg BW dose was the lowest dose that significantly reduced all hemodynamic parameters from baseline when compared to control. When the potential actives were provided at equivalent doses to those found in 50 mg PFPE/kg BW, the EA and AF significantly reduced all measured hemodynamic parameters from baseline when compared to control. GABA did not significantly affect any hemodynamic parameters compared to control and significantly increased heart rate. These direct measurements indicate that PFPE can decrease hemodynamic parameters in SHR and indicate that EA and AF are active compounds that contribute to the antihypertensive effects of PFPE supplementation. While these results are encouraging, detailed mechanistic studies are needed to determine the putative value of PFPE for blood pressure control in humans.