芹菜素舒张血管作用及其机制研究

目的研究芹菜素的舒血管作用及机制。方法大鼠胸主动脉环张力测定法。腹腔注射1%戊巴比妥钠麻醉大鼠,迅速游离大鼠胸主动脉,剪成3～4mm的血管环。血管环悬挂于20ml 95%O2和5%CO2饱和的37℃Kreb液中,以BIO-PAC MP150系统记录血管环张力,研究芹菜素对苯肾上腺素(phenylephrine,PE)预收缩主动脉环张力的作用、各种内皮阻断剂对芹菜素舒张血管作用的影响、钾通道阻断剂对芹菜素舒张血管作用的影响以及芹菜素舒张血管与钙通道的关系。结果芹菜素不影响血管环的静息张力。芹菜素在有或无内皮的血管环上均可剂量依赖性地减小苯肾上腺素(PE)预收缩的血管张力,但是在内皮完整的血管环上,这一作用显著大于去内皮血管环(P<0.05)。用L-N-硝基精氨酸甲酯(L-NAME)、亚甲蓝(MB)孵育内皮完整的血管环后,可明显抑制芹菜素引发的血管舒张,与未经处理的内皮完整血管环组相比有显著性差异(P<0.05)。而预先给予吲哚美辛并不能抑制芹菜素引发的血管舒张作用。4-氨基吡啶(4-AP)、5-羟基癸酸(5-HD)、四乙氨(TEA)、氯化钡(BaCl2)均能显著抑制芹菜素对PE预收缩去内皮血管环的舒张作用(P<0.05)。在无钾环境下,芹菜素对PE引起的血管环收缩有显著抑制作用(P<0.05)。芹菜素对高钾引起的血管环收缩也具有显著的抑制作用(P<0.05)。无钙环境下,芹菜素可显著降低加入Ca2+引起的血管张力的升高(P<0.05)。结论芹菜素具有显著的舒血管作用,其机制涉及到NO介导的信号传导途径,与抑制电压依赖性钙通道、受体操纵性钙通道以及细胞外钙内流受抑和钾通道激活有关。     

Effects of dietary oleic-rich oils (virgin olive and high-oleic-acid sunflower) on vascular reactivity in Wistar-Kyoto and spontaneously hypertensive rats

The effects of two monounsaturated fatty acid (MUFA)-rich diets, containing virgin olive oil (OO) and high-oleic-acid sunflower oil (HOSO), on development of vascular response from isolated thoracic rat aorta and lipid composition and fatty acid composition were studied and compared with samples from rats fed on a control diet. Dietary MUFA oils were fed for 6 weeks to spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats from 4 weeks of age. The maximum contraction of aortic ring preparations in response to phenylephrine (10(-6) m) was significantly decreased in SHR rats fed with OO (0.81 (sem 0.05) v. 1.18 (sem 0.09) g, and treatment with HOSO did not alter the phenylephrine-induced contractions. The relaxant responses to acetylcholine (10(-5) m) were significantly enhanced (30.03 (sem 0.70) v. 18.47 (sem 0.28) %, in the rings from SHR rats treated with OO, and were more pronounced than in WKY rats In the same way, OO attenuated the dose-response curves induced by phenylephrine (10(-8)-10(-5) m) from SHR rats, accompanied with a slower contraction. These results suggest that only the chronic feeding of OO diet was able to attenuate the vascular response of rat aorta. In addition, an increase in phospholipid content (186.7 (sd 3.2) v. 159.1 (sd 11.3) g/kg, and changes in the fatty acid composition of aorta (mainly a decrease in arachidonic acid) could contribute to improving endothelial function. Therefore, the effects can not be attributed exclusively to the content of MUFA (mainly oleic acid). Other components of OO, such as polyphenols, not present in HOSO, may help to explain the vascular protective effect of OO consumption.     

Arsenic-induced dysfunction in relaxation of blood vessels

Several epidemiological studies have suggested that exposure to arsenic is strongly correlated with the development of cardiovascular diseases such as hypertension. To determine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on vasorelaxation using isolated rat aortic rings in an organ-bath system. Treatment with arsenite inhibited acetylcholine-induced relaxation of the aortic rings in a concentration-dependent manner, whereas several other arsenic species did not have any effect. Consistent with these findings, the levels of guanosine 3',5'-cyclic monophosphate (cGMP) in the aortic rings were significantly reduced by arsenite treatment. In cultured human aortic endothelial cells, treatment with arsenite resulted in a concentration-dependent inhibition of endothelial nitric oxide synthase (eNOS). In addition, higher concentrations of arsenite decreased the relaxation induced by sodium nitroprusside (an NO donor) and 8-Br-cGMP (a cGMP analog) in aortic rings without endothelium. These in vitro results indicate that arsenite is capable of suppressing relaxation in blood vessels by inhibiting eNOS activity in endothelial cells and by impairing the relaxation machinery in smooth muscle cells. In vivo studies revealed that the reduction of blood pressure by acetylcholine infusion was significantly suppressed after arsenite was administered intravenously to rats. These data suggest that an impairment of vasomotor tone due to arsenite exposure may be a contributing factor in the development of cardiovascular disease.     

Differential Effects of Methanol on Rat Aortic Smooth Muscle

LI, W., B. T. ALTURA AND B. M. ALTURA. Differential effects of methanol on rat aortic smooth muscle. Alcohol 16(3) 221–229, 1998.—The effects of methanol on isolated segments of rat aorta were investigated. In the absence of any vasoactive agent, methanol (5–675 mM) failed to alter basal tension. In rat aortic rings precontracted with high K⁺ (30 mM), methanol elicited a concentration-related relaxation at concentrations of from 5 to 675 mM. The K⁺-induced contraction in the presence of endothelium was more strongly inhibited by methanol than in the absence of endothelium. The effective concentration producing approximately 50% of the maximal relaxation response (ED₅₀) to methanol was about 96 mM. Methanol-induced relaxations could not be abolished either by 5 × 10⁻⁵ M N-nitro-l-arginine methyl ester (l-NAME) or N^G-nitro-l-arginine (l-NNA), both selective inhibitors of nitric oxide (NO) formation; these relaxations were not potentiated by addition of excess l-arginine. An inhibitor of prostanoid synthesis, indomethacin (10⁻⁵ M), had no effects on methanol-induced relaxation. Removal of extracellular Ca²⁺ ([Ca²⁺]_o) resulted in almost complete inhibition of the relaxant effects of methanol on rat aortic ring segments. Marked attenuation of the relaxation responses of intact arteries to methanol was obtained after buffering intracellular Ca²⁺ ([Ca²⁺]_i) with 10 μM BAPTA-AM. In 5-hydroxytryptamine (5-HT, 2.5 μM)- or phenylephrine (PE, 0.1 μM)-precontracted rat aortic rings, methanol amplified contractile responses to 5-HT and PE; these increased responses were concentration dependent. No significant differences in these methanol potentiated responses were found between aorta with or without endothelial cells. The amplified rat aortic smooth muscle responses induced by methanol after PE could be modified only by phentolamine, an antagonist of PE, while responses to 5-HT could be inhibited by methysergide (an antagonist of 5-HT) and by phentolamine, diphenhydramine, and haloperidol. Pretreatment with 50, 200, and 500 mM methanol increased rat aortic contractile responses induced by 5-HT and PE. Our results suggest that: (a) acute methanol exposure relaxes rat aortic smooth muscle contractile responses induced by high K⁺, leading to vessel relaxation. This relaxation effect of methanol is endothelium-dependent, clearly Ca²⁺ dependent, and independent of endogenous vasodilators such as acetylcholine, histamine, catecholamines, serotonin, or PG. (b) Methanol seems to increase potassium current by shifting the potential towards more negative values in depolarized vascular muscle cell membranes, probably inducing hyperpolarization of the cell membranes leading to a repolarization. (c) In contrast to the relaxant responses, methanol protentiates contractile response of rat aorta to 5-HT and PE.     

Effect of palm oil on blood pressure, endothelial function and oxidative stress

The pathogenesis of hypertension has been associated with endothelial dysfunction and oxidative stress. We have previously shown that palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidants vitamins, reduces oxidative stress-induced hypertension in normal rats. Here, we investigated the cardiovascular effects of natural vitamin-rich PO using the Dahl Salt-sensitive hypertension model. Male rats were fed either a high salt (8%NaCl, HS) or low salt (0.3% NaCl, LS) diet with or without PO (Carotino, 5 g/kg daily) for four weeks. Mean arterial pressure (MAP), heart rate, blood flow and vascular resistance, vascular reactivity in vitro as well as remodelling of second-order mesenteric arteries were measured. Plasma levels of nitric oxide (NO), prostacyclin, thromboxane A(2) (TXA(2)) and isoprostane (ISO), were determined by enzyme immunoassay. Plasma, heart and kidney GSH and GSSG levels were analyzed by HPLC and aortic superoxide ((.)O(2)-) production by fluorescence spectrometry. High salt induced an elevation in MAP that was associated with decreased NO, prostacyclin and GSH: GSSG ratio. Plasma ISO and TXA(2), aortic and renal vascular resistance as well as aortic (.)O(2)- were increased. Palm oil reduced MAP, plasma TXA(2) and vascular resistance of the renal and aortic arteries, and increased the GSH: GSSG ratio and NO in the LS group. The HS-induced elevation in ISO and (.)O(2)- production and the reductions in kidney GSH: GSSG ratio, were attenuated by PO. The effect of PO was also associated with a reduced vessel wall-thickness: lumen diameter ratio and a greater relaxant effect of mesenteric arteries to acetylcholine, in the LS group. The mortality associated with HS was reduced by PO. Thus, palm oil attenuates the progression of salt-induced hypertension and mortality, via mechanisms involving modulation of endothelial function and reduction in oxidative stress.     

红曲降血压的血管机制:抑制平滑肌钙通道并激发其一氧化氮释放

目的:探讨红曲的降血压机制。方法和结果:在离体血管环,去甲肾上腺素(NE)预刺激使血管收缩后加入红曲5mg/ml可明显舒张血管,舒张百分比为(70.84±14.74)%。这一舒张血管作用与血管内皮完整度无关。加入吲哚美辛(Indo),阻断前列腺环素(PGI)生成,对红曲的舒张血管作用没有影响(P>0.05)。而加入左旋硝基精氨酸(L-NNA)阻断平滑肌细胞的NO合成,则可明显抑制红曲的舒张血管作用(P<0.05)。红曲可使CaCl2、KCl和NE量效曲线均明显右移(P<0.05),表明红曲可抑制细胞膜钙通道,包括电位调控性钙通道(VOC)和受体调控性钙通道(ROC)。NE收缩血管反应中Ca2+来自细胞内和细胞外,红曲对细胞内钙引起的收缩没有影响,但可明显抑制细胞外钙引起的收缩。结论:红曲可通过刺激平滑肌细胞产生NO和抑制钙通道而引起血管舒张,这可能是其降血压的主要血管机制。     

Triacylglycerol-rich lipoproteins derived from healthy donors fed different olive oils modulate cytokine secretion and cyclooxygenase-2 expression in macrophages: the potential role of oleanolic acid

Purpose  

Current evidence suggests that consumption of virgin olive oil (VOO) helps to protect against the development of atherosclerosis and that minor components such as oleanolic acid contribute to this effect. In this study, the effects of triacylglycerol-rich lipoproteins (TRLs) derived from olive oil on inflammatory processes in macrophages and how they are modulated by oleanolic acid was investigated.     

高胆固醇膳食对兔动脉壁一氧化氮合成的影响

动脉内皮及其一氧化氮（NO）代谢正常与否，对维持正常的血管功能至关重要。高脂高胆固醇膳食对动脉壁内皮一氧化氮（NO）合成的影响尚无定论。本研究在雄性纯种新西兰兔中，观察高脂高胆固醇膳食对动脉内皮壁一氧化氮合成影响。结果表明：高脂高胆固醇膳食8周后，内皮型一氧化氮合酶（eNOS）mRNA表达下降、总NOS活力减弱、血浆一氧化氮代谢产物（NOP）水平降低（P＜0．05）；血浆超氧歧化酶（SOD）减低，内皮素（ET）水平上升。结果提示：高脂高胆固醇膳食引起高脂血症，可损害动脉内皮，降低NO合成酶的基因表达，抑制NO的合成。     

Opposite vascular activity of (R)-apomorphine and its oxidised derivatives. Endothelium-dependent vasoconstriction induced by the auto-oxidation metabolite

We have synthetised a series of oxidised apomorphine derivatives (orto and para quinones 2-5), in order to analyse their vascular activity. We have performed radioligand binding assays on rat cortical membranes and functional studies on rat aortic rings. Instead the relaxant activity exhibited by (R)-apomorphine, o-quinones 2, 4, show contractile activity dependent on endothelium in rat aortic rings. Compound 2, the main metabolite of (R)-apomorphine auto-oxidation, was the product which showed enhanced contractile activity by a complex mechanism related to activation of Ca(2+) channels through release and/or inhibition of endothelial factors. Moreover, this compound disrupts the endothelial function as shows the lack of response to acetylcholine observed in vessels pretreated with it.     

原儿茶酸通过eNOS-NO-cGMP通路改善ApoE-/-小鼠血管内皮舒张功能

目的探讨原儿茶酸(PCA)对ApoE基因敲除小鼠(ApoE-/-)血管内皮舒张功能的影响及可能机制。方法45只雄性ApoE-/-小鼠随机分为3组:对照组喂养普通AIN-93G饲料(Con组)、低剂量PCA组(0.0003%w/w,L-PCA组)、高剂量PCA组(0.003%w/w,H-PCA组),干预4 w后观察小鼠胸主动脉舒张功能、eNOS及其磷酸化(phos-eNOSser1177)蛋白水平、cGMP和NO的水平。另外,采用氧化型低密度脂蛋白(ox-LDL)造成原代小鼠主动脉内皮细胞(MAECs)损伤模型,评价PCA对细胞eNOS及其磷酸化(phos-eNOSser1177)蛋白水平和NO水平的影响。结果H-PCA组小鼠动脉舒张功能、phos-eNOSser1177表达、cGMP和NO水平分别显著高于对照组和L-PCA组;加入内皮型一氧化氮合酶抑制剂(L-NAME)或鸟苷酸环化酶抑制剂(ODQ)后,PCA对小鼠动脉血管舒张功能保护作用下降。细胞实验结果显示PCA对eNOS蛋白表达和NO无影响,但显著提高phos-eNOSser1177的水平。结论原儿茶酸可以改善血管内皮舒张功能,其机制可能与激活eNOS-NO-cGMP通路有关。     

Momordin Ic and oleanolic acid from Kochiae Fructus reduce carbon tetrachloride-induced hepatotoxicity in rats

Hepatoprotective effects of momordin Ic and oleanolic acid obtained from Kochiae Fructus (KF), the fruit of a traditional Oriental medicinal plant, were evaluated against carbon tetrachloride (CCl4)-induced liver damage in rats. Male Sprague-Dawley rats were divided into four groups: control, CCl4-treated, CCl4 plus momordin Ic-treated (MMDIc-CCl4), and CCl4 plus oleanolic acid-treated (OAA-CCl4). Momordin Ic (30 mg/kg of body weight) and oleanolic acid (30 mg/kg of body weight) were orally administered once a day for 14 days. A mixture of 0.2 mL/100 g of body weight of CCl4 in olive oil (1:1, vol/vol) was injected 30 minutes after the final administration of momordin Ic and oleanolic acid. The momordin Ic and oleanolic acid pretreatments resulted in significantly lower serum transaminase, lactic dehydrogenase, and gamma-glutamyltransferase levels in the CCl4-treated rats. The CCl4-treated rats had significantly lower activities of glutathione, glutathione reductase, glutathione S-transferase, superoxide dismutase, catalase, and glutathione peroxidase. However, pretreatment with momordin Ic and oleanolic acid reduced the effect of CCl4 and helped maintain levels of the enzymes. Pretreatment with momordin Ic and oleanolic acid resulted in significantly lower production of aminopyrine N-demethylase and aniline hydroxylase in the CCl4-treated rats. Pretreatment with momordin Ic resulted in lower catalase and aminopyrine N-demethylase activity induction by CCl4, towards normalization. Momordin Ic and oleanolic acid obtained from KF appear to contribute to alleviating the adverse effects of CCl4 treatment by enhancing the hepatic antioxidant defense system.     

Physical training ameliorates chronic alcohol-induced hypertension and aortic reactivity in rats

AIMS: The aim of this study was to investigate the interactive effect of physical training and chronic ethanol ingestion on changes in blood pressure (BP) and aortic reactivity response in rats. METHODS: Male Fisher rats were divided into four groups of seven animals each and treated as follows: (i) control (5% sucrose, orally) daily for 12 weeks; (ii) ethanol (4 g kg(-1), orally) daily for 12 weeks; (iii) exercise training on treadmill followed by sucrose daily for 12 weeks; (iv) exercise training on treadmill followed by ethanol daily for 12 weeks. The body weight and BP were recorded every week. The animals were anaesthetized with pentobarbital after 12 weeks; blood and thoracic aorta were isolated and analysed for ethanol and reactivity response using tissue bath technique, respectively. RESULTS: The data show that exercise training significantly lowered the weight gain 6-12 weeks in ethanol-treated rats compared to ethanol alone or control rats. The systolic and mean BP significantly elevated 6-12 weeks, whereas diastolic BP elevated 8-12 weeks after ethanol ingestion. Exercise training lowered the BP close to the normal control values in ethanol fed rats. Blood ethanol level significantly elevated in ethanol group but decreased in exercise plus alcohol group. Aortic contractile response to phenylephrine in ethanol or control groups was attenuated by training with or without intact endothelium. Ethanol significantly reduced the aortic relaxation response to acetylcholine whereas training enhanced the relaxation response with intact endothelium. The relaxation responses to adenosine and sodium nitroprusside in the aortic ring segments of rats with or without endothelium were decreased in ethanol group which were attenuated by exercise training. CONCLUSIONS: Physical training attenuates the chronic ethanol-induced hypertension via reduction of body weight, clearance of ethanol, and augmentation of the aortic endothelial relaxation response in rats.     

Molecular Mechanisms Underlying the Effects of Olive Oil Triterpenic Acids in Obesity and Related Diseases

Dietary components exert protective effects against obesity and related metabolic and cardiovascular disturbances by interfering with the molecular pathways leading to these pathologies. Dietary biomolecules are currently promising strategies to help in the management of obesity and metabolic syndrome, which are still unmet medical issues. Olive oil, a key component of the Mediterranean diet, provides an exceptional lipid matrix highly rich in bioactive molecules. Among them, the pentacyclic triterpenic acids (i.e., oleanolic acid) have gained clinical relevance in the last decade due to their wide range of biological actions, particularly in terms of vascular function, obesity and insulin resistance. Considering the promising effects of these triterpenic compounds as nutraceuticals and components of functional foods against obesity and associated complications, the aim of our review is to decipher and discuss the main molecular mechanisms underlying these effects driven by olive oil triterpenes, in particular by oleanolic acid. Special attention is paid to their signaling and targets related to glucose and insulin homeostasis, lipid metabolism, adiposity and cardiovascular dysfunction in obesity. Our study is aimed at providing a better understanding of the impact of dietary components of olive oil in the long-term management of obesity and metabolic syndrome in humans.     

The role of endogenous free radicals of nitric oxide (NO)]

The role of endothelium in vasodilatation has only emerged in the last ten years. It was observed that many endogenous substances from endothelial cells triggered the release of a substance which was named endothelium-derived relaxing factor (EDRF). Later has been showed that NO accounted for most if not all of the biological activity of EDRF. The endothelial synthesis of NO originates from L-arginine and could be blocked by the methyl analogue (e.g. NG-mono-methyl-L-arginine). Beside endothelial cells NO could be identified in several mammalian tissues including brain, hepatocytes, lung and macrophages. NO mediated the control of vascular tone and blood pressure via vascular smooth muscle cells which exert relaxation and constriction of blood vessels. It is considered NO represents signal for the guanylate cyclase system which regulates the intracellular concentration of Ca2+ ions. It is well known that the concentration of Ca2+ ions play discern direct role in the relaxation and contraction of smooth muscle, respectively.     

The flavonoid luteolin induces nitric oxide production and arterial relaxation

Purpose

Luteolin, a flavone present in many foods and medicinal plants, may have beneficial effects on various human chronic diseases. In the present study, we investigated the hypothesis that luteolin can directly act on vascular endothelial cells (ECs), leading to nitric oxide (NO) production and subsequent vascular relaxation.

Methods

Rat aortic rings were mounted in organ bath. Luteolin was added cumulatively, and vessel relaxation of rat aortic rings precontracted with phenylephrine (PE) or potassium was recorded. Endothelial nitric oxide synthase (eNOS) phosphorylation at Ser1177 and NO production from aortic rings and primary human aortic endothelial cells (HAECs) exposed to luteolin were measured by using Western blot and fluorometric assay, respectively.

Results

Luteolin dose-dependently (10–100 μmol/L) elicited relaxation of PE- or potassium-contracted aortic rings. The vasorelaxation effect of luteolin was attenuated by the eNOS inhibitor, N-nitro-l-arginine methyl ester, suggesting that this luteolin action is at least partially mediated by activating eNOS activity. We further found that luteolin dose-dependently (10–100 μmol/L) increased eNOS phosphorylation at Ser1177 (up to 1.9-fold) in isolated rat rings. Consistently, exposure of HAECs to luteolin also increased eNOS phosphorylation and NO production.

Conclusions

Luteolin may be a vascular protective agent by directly acting on vascular ECs to stimulate NO-dependent vascular dilatation.     

Olive oil decreases both oxidative stress and the production of arachidonic acid metabolites by the prostaglandin G/H synthase pathway in rat macrophages

Fish oil has a preventive role in cardiovascular and inflammatory diseases, but little is known about the effect of olive oil, which is widely consumed in Mediterranean regions. We examined the influence of dietary olive oil, corn oil and fish oil-rich diets on the production of superoxide anion (O2-) and nitric oxide (.NO) by resident macrophages stimulated by phorbol 12-myristate 13-acetate (PMA) and their effect on arachidonic acid release, prostaglandin G/H synthase-2 (PGHS-2) expression and the subsequent prostaglandin E(2) production. Resident peritoneal macrophages stimulated by PMA from rats fed with olive oil or corn oil had the same level of O2- production, but these levels were increased by the fish oil diet. Olive oil and the fish oil diets increased .NO and decreased arachidonic acid mobilization and the production of prostaglandin E(2). PGHS-2 expression, however, was not affected by diet. We conclude that although olive oil and fish oil reduce arachidonic acid mobilization and subsequent metabolism through the PGHS-2 pathway in PMA-stimulated macrophages, only olive oil offers an additional beneficial effect by increasing .NO/O2- production.     

Argan (Argania spinosa) oil lowers blood pressure and improves endothelial dysfunction in spontaneously hypertensive rats

Traditionally hand-pressed argan oil, obtained from Argania spinosa seeds, is eaten raw in south-west Morocco; its rich composition of tocopherols, MUFA and PUFA make a study of its actions on risk factors for CVD, such as hypertension, interesting. The effects of 7 weeks of treatment with argan oil (10 ml/kg) on the blood pressure and endothelial function of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats were investigated. Systolic blood pressure and heart rate were measured every week by the tail-cuff method and endothelial function was assessed by carbachol (10(-8) to 10(-4) M)-induced relaxations of aortic rings and small mesenteric arteries pre-contracted with phenylephrine. Argan-oil administration reduced the mean blood pressure of SHR after the fifth week of treatment (P<0.05) and increased (P<0.01) the endothelial responses of arteries from SHR. The NO synthase inhibitor, L-N-omega-nitroarginine (3 x 10(-5) M) revealed a greater participation of NO in the relaxant effect after the treatment. When cyclooxygenase (COX) was blocked with indomethacin (10(-5) M), an involvement of COX products in the endothelium-dependent response was characterized. Enzyme immunoassay of thromboxane B2 showed a significant decrease (P<0.05) in the release of thromboxane A2 in both aorta and small mesenteric artery after argan-oil treatment of SHR. Experiments in the presence of the thromboxane A2-prostaglandin H2 receptor antagonist ICI 192,605 (10(-5) M) confirmed this result. Results after incubation with the antioxidants superoxide dismutase and catalase suggested that a decreased oxidative stress might contribute to explain the beneficial effects of argan-oil treatment.     

Antihypertensive and cardioprotective effects of pumpkin seed oil

Pumpkin seed oil is a natural product commonly used in folk medicine for treatment of prostatic hypertrophy. In the present study, the effects of treatment with pumpkin seed oil on hypertension induced by the nitric oxide synthase inhibitor N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME) (50?mg /kg/day) in rats were studied and compared with those of the calcium channel blocker amlodipine. Pumpkin seed oil (40 or 100?mg/kg), amlodipine (0.9?mg/kg), or vehicle (control) was given once daily orally for 6 weeks. Arterial blood pressure (BP), heart rate, electrocardiogram (ECG) changes, levels of serum nitric oxide (NO) (the concentrations of nitrite/nitrate), plasma malondialdehyde (MDA), blood glutathione, and erythrocytic superoxide dismutase activity were measured. Histopathological examination of heart and aorta was conducted as well. L-NAME administration resulted in a significant increase in BP starting from the second week. Pumpkin seed oil or amlodipine treatment significantly reduced the elevation in BP by L-NAME and normalized the L-NAME-induced ECG changes-namely, prolongation of the RR interval, increased P wave duration, and ST elevation. Both treatments significantly decreased the elevated levels of MDA and reversed the decreased levels of NO metabolites to near normal values compared with the L-NAME-treated group. Amlodipine also significantly increased blood glutathione content compared with normal (but not L-NAME-treated) rats. Pumpkin seed oil as well as amlodipine treatment protected against pathological alterations in heart and aorta induced by L-NAME. In conclusion, this study has shown that pumpkin seed oil exhibits an antihypertensive and cardioprotective effects through a mechanism that may involve generation of NO.     

Palm oil tocotrienol fractions restore endothelium dependent relaxation in aortic rings of streptozotocin-induced diabetic and spontaneously hypertensive rats

Diabetes and hypertension are closely associated with impaired endothelial function. Studies have demonstrated that regular consumption of edible palm oil may reverse endothelial dysfunction. The present study investigates the effect of palm oil fractions: tocotrienol rich fraction (TRF), α-tocopherol and refined palm olein (vitamin E–free fraction) on the vascular relaxation responses in the aortic rings of streptozotocin-induced diabetic and spontaneously hypertensive rats (SHR). We hypothesize that the TRF and α-tocopherol fractions are able to improve endothelial function in both diabetic and hypertensive rat aortic tissue. A 1,1-diphenyl picryl hydrazyl assay was performed on the various palm oil fractions to evaluate their antioxidant activities. Endothelium-dependent (acetylcholine) and endothelium-independent (sodium nitroprusside) relaxations were examined on streptozotocin-induced diabetic and SHR rat aorta following preincubation with the different fractions. In 1-diphenyl picryl hydrazyl antioxidant assay, TRF and α-tocopherol fractions exhibited a similar degree of activity while palm olein exhibited poor activity. TRF and α-tocopherol significantly improved acetylcholine-induced relaxations in both diabetic (TRF, 88.5% ± 4.5%; α-tocopherol, 87.4% ± 3.4%; vehicle, 65.0 ± 1.6%) and SHR aorta (TRF, 72.1% ± 7.9%; α-tocopherol, 69.8% ± 4.0%, vehicle, 51.1% ± 4.7%), while palm olein exhibited no observable effect. These results suggest that TRF and α-tocopherol fractions possess potent antioxidant activities and provide further support to the cardiovascular protective effects of palm oil vitamin E. TRF and α-tocopherol may potentially improve vascular endothelial function in diabetes and hypertension by their sparing effect on endothelium derived nitric oxide bioavailability.