Blood pressure lowering,cardiovascular inhibitory and bronchodilatory actions of Achillea millefolium

Achillea millefolium Linn. (Asteraceae) is used in folk medicine for the treatment of overactive cardiovascular and respiratory ailments. This study describes its hypotensive, cardio‐depressant, vasodilatory and bronchodilatory activities. The crude extract of Achillea millefolium (Am.Cr) caused a dose‐dependent (1–100 mg/kg) fall in arterial blood pressure of rats under anaesthesia. In spontaneously beating guinea‐pig atrial tissues, Am.Cr exhibited negative inotropic and chronotropic effects. In isolated rabbit aortic rings, Am.Cr at 0.3–10 mg/mL relaxed phenylephrine (PE, 1 µm ) and high K⁺ (80 mm )‐induced contractions, as well as suppressed the PE (1 µm ) control peaks obtained in Ca⁺⁺‐free medium, like that caused by verapamil. The vasodilator effect of Am.Cr was partially blocked by N_ω‐nitro‐l ‐arginine methyl ester in endothelium intact preparations. In guinea‐pig tracheal strips, Am.Cr inhibited carbachol (CCh, 1 µm ) and K⁺‐induced contractions. These results indicate that Achillea millefolium exhibits hypotensive, cardiovascular inhibitory and bronchodilatory effects, thus explaining its medicinal use in hyperactive cardiovascular and airway disorders, such as hypertension and asthma. Copyright © 2010 John Wiley & Sons, Ltd.     

Anti-hypertensive effect of water extract of danshen on renovascular hypertension through inhibition of the renin angiotensin system

A study was designed to elucidate the mechanism of anti-hypertensive effects of danshen in the two-kidney, one clip (2K1C) Goldblatt renovascular hypertensive model, which is the renin-angiotensin system (RAS)-dependent hypertensive model. We investigated the effects of water extracts of danshen on the angiotensin converting enzyme (ACE) activities, systolic blood pressure (SBP), and hormone levels in the plasma of 2K1C rats. ACE activity was inhibited by the addition of danshen extract in a dose-dependent manner. SBP was decreased significantly after administration of danshen extract in 2K1C, whereas plasma renin activity (PRA) was not changed. The plasma concentration of aldosterone (PAC) was decreased significantly in 2K1C group administered with Danshen extract, whereas the plasma concentration of ANP was increased by administration of danshen extract for three weeks. These results suggest that danshen has an anti-hypertensive effect through the inhibition of ACE, an essential regulatory enzyme of RAS.     

Cardiovascular active substances from the straw mushroom,Volvariella volvacea

The straw mushroom Volvariella volvacea is one of the common edible mushrooms in Hong Kong and is widely cultivated in Southeast Asian countries. It has been reported to produce a hypotensive response in animals including humans. An aqueous extract of the mushroom (SME) was prepared and given through intravenous injections to normotensive rats. The blood pressure changes produced by SME alone or in the presence of various drugs were studied. The effects of SME on the kidney function of water-loaded rats and on isolated tissue preparations of the tail artery and right atrium were examined. An i.v. injection of SME produced a hypotensive effect in rats with an ED₅₀ of 25 mg dry weight/kg body weight. This hypotensive effect of SME was attenuated or blunted in the presence of hexamethonium, phentolamine, pyrilamine and cimetidine suggesting the involvement of the α-adrenergic component of the autonomic system and/or histamineergic stimulation. SME did not increase urinary excretion nor sodium diuresis. It produced positive chronotropic and inotropic effects on isolated right atria and induced contraction of isolated tail artery strips. This latter contractile response was inhibited by antagonists of serotonin and α-adrenoceptor, ketanserin and phentolamine respectively. Partial purification using dialysis and liquid chromatography revealed that the hypotensive active substances had molecular masses between 8000 and 12000 dalton. These substances were heat stable and resistant to trypsin digestion. In view of the similarity in blood pressure and cardiovascular response, SME might contain serotonin-like substances.     

Ligustilide reduces phenylephrine induced-aortic tension in vitro but has no effect on systolic pressure in spontaneously hypertensive rats

Radix Angelica sinensis, known as Danggui in Chinese, has been used to treat cardiovascular diseases in traditional Chinese medicine for a long time. Experimental evidence showed that the essential oil of Danggui could reduce blood pressure in rabbits, cats or hypertensive dogs when given intravenously. In this study, we investigated the effects of Z-ligustilide, the main lipophilic component of the essential oil of Danggui on aortic tension induced by phenylephrine, an alpha-adrenergic agonist, in vitro and the systolic blood pressure in SHR rats. We demonstrated for the first time that ligustilide can significantly reduce the phenylephrine-induced aortic tension in vitro with IC(50) about 64 mug/ml, but has no in vivo effect on systolic blood pressure in SHR rats when administrated orally. The data on transport of ligustilide across Caco-2 monolayer suggested an efficient intestinal absorption of ligustilide in vivo, implying that the non-effectiveness of ligustilide in vivo is not due to the poor absorption in the gastrointestinal tract. Further studies on whether ligustilide is one of the main anti-hypertensive components of the essential oil are needed.     

Antispasmodic,bronchodilator and blood pressure lowering properties of Hypericum oblongifolium – possible mechanism of action

The crude extract of Hypericum oblongifolium (Ho.Cr), which tested positive for flavonoids, saponins and tannins caused concentration‐dependent (0.1–1.0 mg/mL) relaxation of spontaneous and high K⁺ (80 mM)‐induced contractions in isolated rabbit jejunum preparations, suggesting a Ca⁺⁺ antagonistic effect, which was confirmed when pretreatment of the tissue with Ho.Cr produced a rightward shift in the Ca⁺⁺ concentration‐response curves, like that caused by verapamil. Ho.Cr relaxed carbachol (1 μM) and high K⁺‐induced contractions in guinea pig tracheal preparations. It caused a dose‐dependent (3–100 mg/kg) fall in arterial blood pressure of rats under anesthesia. In isolated guinea pig atria, Ho.Cr caused inhibition of both atrial force and rate of spontaneous contractions. When tested in rabbit aortic rings, Ho.Cr exhibited a vasodilator effect against phenylephrine (1 μM) and high K⁺‐induced contractions. These results indicate that Ho.Cr possesses gastrointestinal, respiratory and cardiovascular inhibitory effects, mediated via a Ca⁺⁺ antagonist mechanism. Copyright © 2009 John Wiley & Sons, Ltd.     

Hypotensive effect of aqueous saffron extract (Crocus sativus L.) and its constituents,safranal and crocin,in normotensive and hypertensive rats

In this study, the effects of saffron (Crocus sativus) stigma aqueous extract and two active constituents, crocin and safranal, were investigated on blood pressure of normotensive and desoxycorticosterone acetate‐induced hypertensive rats. Three doses of crocin (50, 100 and 200 mg/kg), safranal (0.25, 0.5 and 1 mg/kg) and the aqueous extract (2.5, 5 and 10 mg/kg) were administered intravenously in different groups of normotensive and hypertensive animals and their effects on mean arterial blood pressure (MABP) and heart rate (HR) were evaluated. The aqueous extract of saffron stigma, safranal and crocin reduced the MABP in normotensive and hypertensive anaesthetized rats in a dose‐dependent manner. For example, administrations of 10 mg/kg of aqueous extract, 1 mg/kg of safranal and 200 mg/kg of crocin caused 60 ± 8.7, 50 ± 5.2 and 51 ± 3.8 mmHg reductions in MABP, respectively. It can be concluded that the aqueous extract of saffron stigma has hypotensive properties which appear to be attributable, in part, to the actions of two major constitutes of this plant, crocin and safranal. It seems that safranal is more important than crocin for lowering down blood pressure of rats. Copyright © 2009 John Wiley & Sons, Ltd.     

山莨菪碱对内毒素休克狗心血管活动的效应

给麻醉狗静脉注射大肠杆菌 O_(111)B_4内毒素5mg/kg 引起休克,60分钟后经股静脉注入山莨菪碱5mg/kg 后,可使心率加快,平均动脉压回升,左心室心肌收缩能力改善,肾血流阻力降低,肾血流量和尿量都增加。在对照组动物中仅给等容积的生理盐水,未出现上述变化。     

A pharmacological study on Berberis vulgaris fruit extract

Berberis vulgaris fruit (barberry) is known for its antiarrhythmic and sedative effects in Iranian traditional medicine. The effects of crude aqueous extract of barberry on rat arterial blood pressure and the contractile responses of isolated rat aortic rings and mesenteric bed to phenylephrine were investigated. We also examined effect of the extract on potassium currents recorded from cells in parabrachial nucleus and cerebellum rejoins of rat brain. Administration of the extract (0.05-1 mg/100 g body weight of rat) significantly reduced the mean arterial blood pressure and heart rate in anaesthetized normotensive and desoxycorticosteron acetate-induced hypertensive rats in a dose-dependent manner. Concentration-response curves for phenylephrine effects on isolated rat aortic rings and the isolated mesenteric beds in the presence of the extract were significantly shifted to the right. Application of the extract (1-50 microg/ml) shifted the activation threshold voltage to more negative potentials, leading to an enhancement in magnitude of the outward potassium current recorded from cells present in rat brain slices of parabrachial nucleus and cerebellum. This effect on potassium current may explain the sedative and neuroprotective effects of barberry. The present data support the hypothesis that the aqueous extract of barberry has beneficial effects on both cardiovascular and neural system suggesting a potential use for treatment of hypertension, tachycardia and some neuronal disorders, such as epilepsy and convulsion.     

Effects of Vitex doniana Stem Bark Extract on Blood Pressure

The effects of oral and intravenous administration of the stem bark extract of Vitex doniana on blood pressure was investigated in normotensive and hypertensive rats. Oral and intravenous administration of the stem bark extract produced a dose-dependent hypotensive effect in both normotensive and hypertensive rats. The blood pressure was markedly reduced and the reduced level maintained for longer duration when the extract was administered intravenously to hypertensive rats. The present data show that the extract affects the smooth muscle of the vascular system, suggesting a possible therapeutic application as an antihypertensive agent.     

Six weeks oral gavage of a Phyllanthus acidus leaf water extract decreased visceral fat,the serum lipid profile and liver lipid accumulation in middle-aged male rats

Ethnopharmacological relevance

Advancing age is associated with an increased accumulation of visceral fat and liver lipid which is then responsible for an age-related risk for cardiovascular disease. Looking after ourselves well with suitable micronutrients could prevent disease or prolong our healthy cardiovascular functions. In Thai traditional medicine, leaves of Phyllanthus acidus (PA) have been used for many purposes including as an antihypertensive agent and to provide relief from a headache caused by hypertension. We aimed to investigate the effects of a chronic oral administration of PA extracts to middle-aged (12–14 months) rats on their body weight, food intake, body fats, liver and kidney functions, fasting blood glucose and lipid profiles, liver lipid accumulation and on blood pressure.

Materials and methods

Three different kinds of PA extracts were used: (1) a PA water extract, (2) a heated PA water extract, and (3) an n-butanol fraction of the PA water extract, prepared from fresh leaves of Phyllanthus acidus. The rats were orally gavaged with the three PA extracts at 1.0 g/kg body weight or, as a control, with distilled water once a day for 6 weeks. Fasting blood sugar, lipid profile and ALP, SGOT, SGPT, BUN and creatinine levels were measured by enzymatic methods. Liver lipid accumulation was measured using oil red O staining on fresh thin cryostat liver tissue sections. The animal basal blood pressure and heart rate were measured in anesthetized rats via a common carotid artery using a polygraph.

Results

Results showed that after 6 weeks of treatment using gavaged heated PA extract and PA n-butanol extract there were no changes in any of the parameters studied. However, the initial PA water extract caused a slight decrease in the animal body weight with no change in food intake. No changes were observed in the liver and kidney functions (serum ALP, SGOT, SGPT, BUN and creatinine did not change), nor did the fasting blood sugar or triglyceride levels differ significantly. Serum cholesterol, HDL and LDL levels, as well as visceral and subcutaneous adipose tissue and liver lipid accumulation were significantly decreased compared to that of the control group. There were no differences found in the basal systolic and diastolic blood pressure and the basal heart rate between the PA water extract treatment and the control group.

Conclusions

These results indicated that the PA water extract had an effect on lipid metabolisms that resulted in a decrease of the serum lipid profile, visceral and subcutaneous fat, as well as on liver lipid accumulation in middle-aged rats. The active component that is responsible for these effects is likely to be a water soluble substance(s) and is heat labile. As a consequence of these beneficial effects of the PA water extract, it would be a good choice for further development for use as a nutraceutical or health product to prevent and/or to slow down the development of obesity and/or cardiovascular disease.     

Hypotensive and cardio-chronotropic constituents of Tinospora crispa and mechanisms of action on the cardiovascular system in anesthetized rats

Ethnopharmacological relevance

Tinospora crispa has been used in folkloric medicine for the control of blood pressure. We previously found that an extract of Tinospora crispa stems decreased the mean arterial blood pressure (MAP) with a transient decrease, followed by an increase in the heart rate (HR) in rats.

Aim of the study

To identify the active components of the Tinospora crispa extract and investigate the mechanisms of action on blood pressure and heart rate in anesthetized rats.

Materials and methods

The active components of Tinospora crispa extract were separated by column chromatography and a preparative HPLC. The effects and mechanisms of the active compounds on blood pressure and heart rate were studied in anesthetized, normal and reserpinized rats in vivo.

Results

5 active compounds: adenosine, uridine, salsolinol, higenamine and tyramine were isolated. Adenosine decreased MAP and HR and this effect was inhibited by DMPX (A_2A adenosine receptor antagonist). Uridine increased MAP and decreased HR and this was inhibited by suramin but not by DMPX. Salsolinol decreased the MAP and HR and this was inhibited by phentolamine but not by ICI-118,551 (β₂-adrenoceptor antagonist) or atropine. In reserpinized rats, salsolinol had a hypertensive effect that was inhibited by prazosin and phentolamine, but not by atenolol, and caused an increase in HR that was inhibited by atenolol, but not by prazosin or phentolamine. Higenamine decreased the MAP with an increase in HR. The hypotensive effect was inhibited by ICI-118,551 or atenolol, whereas the increase in HR was not inhibited by ICI-118,551. Atenolol inhibited the increase in HR at a small dosage of higenamine but potentiated it at a higher dosage. In reserpinized rats, a small dosage of higenamine tended to potentiate the effect but at a higher dosage it caused inhibition. ICI-118,551 significantly inhibited this hypotensive effect. Tyramine caused an increase in MAP and HR and these effects almost disappeared in reserpinized rats.

Conclusions

The results demonstrate that these 5 compounds from Tinospora crispa acted in concert on the cardiovascular system of anesthetized rats. Salsolinol, tyramine and higenamine acted via the adrenoreceptors, whereas uridine and adenosine acted via the purinergic adenosine A₂ and P₂ receptors to decrease blood pressure with a transient decrease of HR followed by an increase.     

Influence of aqueous extract from Neurada procumbens L. on blood pressure of rats

Neurada procumbens is a desert plant in the Arabian Peninsula. It has been considered edible by Bedouin and has been used traditionally as a medicinal herb. During a screening test of Arabian plants, the aqueous extract of Neurada procumbens increased the blood pressure of anaesthetized normotensive rats when it was administered orally. Further studies proved it elevated the blood pressure of conscious SHR, and produced vasoconstriction on the aortic strips of rats in vitro, which was reduced partially by phentolamine. This study demonstrates that the aqueous extract of the plant has an effect of increasing blood pressure that might be mediated through alpha-adrenergic receptors. Though more investigations are needed to prove its effect in humans, the present study warns that Neurada procumbens might not be so safe as it has been considered, and people, especially those with cardiovascular diseases, should be careful when they use the plant.     

Hypotensive action of Solanum melongena on normotensive rats

The cardiovascular action of Solanum melongena extract (SME) was investigated using in vivo and in vitro preparations. SME produced dose-dependent hypotensive responses in normotensive albino rats. The duration of response was also dose dependent. In pharmacological antagonist studies, the hypotensive action of SME was proved not to be mediated through the autonomic ganglion, the α-adrenoceptor or the histaminergic receptor. SME worked via the β-adrenoceptor and cholinergic (muscarinic) receptor inducing the hypotensive response. A dose-related attenuation of hypotension with increasing dosages of the β-adrenoceptor blocker, propranolol, and the cholinergic receptor blocker, atropine was observed. In vitro studies indicated that the vasorelaxing and negative inotropic effect of SME might be implicated in the hypotensive response. The activities of the β-adrenergic and acetylcholine receptors mediated by SME in turn promoted vasodilation of the resistant vessels and a reduction in cardiac activity respectively. It is also possible that the hypotensive effect of SME could be accounted for by its influence on the activity of the renin-angiotensin system, since a significant difference of the hypotensive response of SME was obtained with captopril. Furthermore, SME induced diuresis in water-loaded rats which might also account for the hypotensive effect observed. SME could be a very potent hypotensive agent.     

Protocatechuic Acid Restores Vascular Responses in Rats With Chronic Diabetes Induced by Streptozotocin

Oxidative stress has been shown to play an important role in development of vascular dysfunction in diabetes. Protocatechuic acid (PCA) has been reported to exert antioxidant and anti‐hyperglycemic activities. Diabetes was induced in male Sprague–Dawley rats by a single intraperitoneal injection of 50 mg/kg streptozotocin (STZ). The rats were maintained in a state of hyperglycemia for 12 weeks. Then, PCA (50 or 100 mg/kg/day) was administered orally or insulin (4 U/kg/day) was subcutaneous injected to the rats for 6 weeks. Blood pressure, vascular responses to vasoactive agents, vascular superoxide production, blood glucose, insulin, malondialdehyde, nitric oxide and antioxidant enzymes were examined. The diabetic rats showed weight loss, insulin deficiency, hyperglycemia, increased oxidative stress, decreased plasma nitric oxide, elevated blood pressure, increased vascular response to phenylephrine and decreased vascular responses to acetylcholine and sodium nitroprusside. PCA significantly decreased blood glucose and oxidative stress, and increased plasma nitric oxide in diabetic rats. Interestingly, PCA treatment restored blood pressure and vascular reactivity, and antioxidant enzyme activity diabetic rats. This study provides the first evidence of the efficacy of PCA in restoring the vascular reactivity of diabetic rats. The mechanism of action may be associated with an alleviation of oxidative stress. Copyright © 2015 John Wiley & Sons, Ltd.     

The effect of Ginkgo biloba extract on mitochondrial oxidative phosphorylation in the normal and ischemic rat heart

Free radical‐induced myocardial damage and impairment of vascular endothelium‐dependent relaxation are amongst the most important mechanisms responsible for ischemic heart injury. Ginkgo biloba leaf extract (GE) has been reported to improve blood circulation in the brain and have a beneficial impact on the cardiovascular system but its cardioprotective effects have not been elucidated yet. Therefore, this study investigated the influence of GE in 70% ethanol (1:5) administered orally to rats on the functions of isolated heart mitochondria under normal and ischemic conditions. Wistar rats were given GE or ethanol (solvent control) at a dosage of 0.32 mL/kg in drinking water for 10 and 18 days, while the control animals received untreated drinking water. Mitochondrial respiration rates were determined oxygraphically. Pyruvate and malate, succinate or palmitoyl‐l ‐carnitine and malate were used as substrates. The GE treatment partially uncoupled mitochondrial oxidation from phosphorylation, reduced the generation of free radicals in the mitochondria, diminished the ischemia‐induced V₃ decrease and the degree of respiration stimulation by exogenous cytochrome c. Thus, these results indicate that GE exerts cardioprotective effects reducing ischemia‐caused impairment of the functions of heart mitochondria. Copyright © 2011 John Wiley & Sons, Ltd.     

Gut modulatory, blood pressure lowering, diuretic and sedative activities of cardamom

ETHNOPHARMACOLOGICAL RELEVANCE: Cardamom (Elettaria cardamomum) is traditionally used in various gastrointestinal, cardiovascular and neuronal disorders. AIM OF THE STUDY: To rationalize cardamom use in constipation, colic, diarrhea, hypertension and as diuretic. MATERIALS AND METHODS: Cardamom crude extract (Ec.Cr) was studied using in vitro and in vivo techniques. RESULTS: Ec.Cr caused atropine-sensitive stimulatory effect in isolated guinea-pig ileum at 3-10mg/ml. In rabbit jejunum preparations, Ec.Cr relaxed spontaneous and K+ (80 mM)-induced contractions as well as shifted Ca++ curves to right, like verapamil. Ec.Cr (3-100mg/kg) induced fall in the arterial blood pressure (BP) of anaesthetized rats, partially blocked in atropinized animals. In endothelium-intact rat aorta, Ec.Cr relaxed phenylephrine (1 microM)-induced contractions, partially antagonized by atropine and also inhibited K+ (80 mM) contractions. In guinea-pig atria, Ec.Cr exhibited a cardio-depressant effect. Ec.Cr (1-10mg/kg) produced diuresis in rats, accompanied by a saluretic effect. It enhanced pentobarbital-induced sleeping time in mice. Bio-assay directed fractionation revealed the separation of spasmogenic and spasmolytic components in the aqueous and organic fractions respectively. CONCLUSION: These results indicate that cardamom exhibits gut excitatory and inhibitory effects mediated through cholinergic and Ca++ antagonist mechanisms respectively and lowers BP via combination of both pathways. The diuretic and sedative effects may offer added value in its use in hypertension and epilepsy.     

Effects of an n-butanol extract from the stem of Tinospora crispa on blood pressure and heart rate in anesthetized rats

Ethnopharmacological relevance

Tinospora crispa has been used in folkloric medicine for control of blood pressure, as an antipyretic, for cooling down the body temperature and for maintaining good health.

Aim of the study

To investigate the effects and mechanisms of action of an n-butanol extract from the stems of Tinospora crispa (T. crispa extract) on blood pressure and heart rate in anesthetized rats.

Materials and methods

Air-dried stems of T. crispa were extracted with water, followed by partitioned extract with chloroform, ethyl acetate, and finally by n-butanol. The n-butanol soluble part was evaporated under reduced pressure and lyophilization to obtain a crude dried powder (T. crispa extract). The effects and mechanisms of the T. crispa extract on blood pressure and heart rate were studied in anesthetized normal and reserpinized rats in vivo in the presence of different antagonists.

Results

T. crispa extract (1-100 mg/kg, i.v.) caused a decrease in mean arterial blood pressure (MAP) and this effect was inhibited by propranolol, phentolamine, atenolol and/or the β₂-antagonist ICI-118,551, but not by atropine or hexamethonium. In reserpinized rats, the T. crispa extract had a dual effect: reduction in hypotensive activity, followed by a small increase in blood pressure. The decrease in MAP in reserpinized rat was slightly potentiated by phentolamine, but inhibited by propranolol or ICI-118,551 only if atenolol and phentolamine were also present. The increase in MAP was potentiated by propranolol and ICI-118,551, but was inhibited by phentolamine. The T. crispa extract had a dual effect on heart rate in the normal rat: a small transient decrease, followed by an increase in heart rate. The positive chronotropic effect of T. crispa extract was inhibited by propranolol, phentolamine and atenolol, but not by ICI-118,551, atropine or hexamethonium. Reserpine potentiated the positive chronotropic effect of the T. crispa extract and this effect was inhibited by propranolol, atenolol and ICI-118,551, but not by phentolamine.

Conclusions

From these results we suggest that T. crispa extract possesses at least three different cardiovascular-active components that act directly via (1) β₂-adrenergic receptors to cause a decrease in blood pressure, and β₁- and β₂-adrenergic receptors to cause an increase in heart rate, (2) α-adrenergic receptors to cause an increase in blood pressure and heart rate, and (3) a non-adrenergic and non-cholinergic pathway to cause a decrease in MAP and heart rate. These findings provide scientific support for the tradition of using this plant to modify the actions of the human cardiovascular system.     

Leaf methanol extract of Bidens pilosa prevents and attenuates the hypertension induced by high-fructose diet in Wistar rats

Chronic fructose treatment in rats has repeatedly been shown to elevate blood pressure in association with insulin resistance and hyperinsulinemia. The purpose of the current study was to investigate the effect of the leaf methanol extract of Bidens pilosa on systolic blood pressure (SBP) and plasma glucose, insulin, cholesterol, triglycerides and creatinine levels in rats with fructose-induced hypertension. Wistar rats that drank a 10% fructose solution for 3-6 weeks showed significant increase not only in plasma insulin and cholesterol levels but also in SBP. B. pilosa extract was able to prevent the establishment of hypertension and lower elevated blood pressure levels. The extract also reduced the highly elevated plasma insulin levels provoked by the high fructose diet. These results suggest that the leaf methanol extract of B. pilosa exerts its antihypertensive effect in part by improving insulin sensitivity.     

Soy‐diet has beneficial effects on cardiovascular parameters that are independent of its lipid effect in male hypercholesterolemic rats

Diet‐induced atherosclerosis is lower in animals fed soy protein. The effects of various soy components have been extensively studied; however, little is known about the effect of crude soybean feeding on hypercholesterolemia‐induced cardiovascular changes. This study investigated the effect of soy feeding on cardiovascular parameters in hypercholesterolemic male rats. Total cholesterol (TC), low density lipoprotein (LDL) and high density lipoprotein cholesterol (HDL), and triglyceride (TG) were measured. Rats were randomly assigned to control, high cholesterol (HC, 2% cholesterol) or HC + soy (HC+S) diets. In the HC+S group, rats received HC diet for 10 weeks followed by 2 weeks of soybean feeding. Arterial blood pressure, TC, TG, LDL and HDL were measured. TC, TG and LDL were higher in HC rats and were not significantly reduced by soybean feeding. Soy feeding reversed the HC‐induced increase in arterial blood pressure and also restored the impaired vascular responses to acetylcholine in isolated aortic rings. Pre‐incubation of HC+S aortic rings with L‐NAME (10^?5 M for 20 min) partially reduced the effects of soy on acetylcholine responses, indicating that the beneficial vascular effects of dietary soy are partially mediated via nitric oxide pathway. Copyright © 2008 John Wiley & Sons, Ltd.     

Phlorizin-like effect of Fraxinus excelsior in normal and diabetic rats

The purpose of this study was to determine the underlying mechanism of the hypoglycaemic activity of the aqueous extract perfusion of Fraxinus excelsior L. (FE) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously and the blood glucose changes were determined within four hours after starting the treatment. Plasma insulin concentrations and glycosuria were determined. The aqueous extract at a dose of 10 mg/kg/h produced a significant decrease in blood glucose levels in normal rats (P < 0.001) and even more in diabetic rats (P < 0.001). This hypoglycaemic effect might be due to an extra-pancreatic action of the aqueous extract of FE, since the basal plasma insulin concentrations were unchanged after FE treatment. A potent increase of glycosuria was observed both in normal and diabetic rats (P < 0.001). We conclude that aqueous extract perfusion of FE caused a potent inhibition of renal glucose reabsorption. This renal effect might be at least one mechanism explaining the observed hypoglycaemic activity of this plant in normal and diabetic rats.