Effect of trandolapril on vascular responsiveness in cholesterol-fed rabbit-isolated arteries

According to the World Health Organisation, cardiovascular disorders are one of the main causes of morbi/mortality in the western world. The effect of trandolapril (0.3 mg kg(-1) day(-1)), a non-sulphydryl angiotensin-converting enzyme (ACE) inhibitor, on the vascular responsiveness in aorta isolated from hypercholesterolemic rabbits was examined. Three groups of rabbits (n=30) were used: Group 0 (control group); Group 1 (hypercholesterolemic group, 0.5% (wt/wt) cholesterol-enriched diet) and Group 2 (hypercholesterolemic+trandolapril 0.3 mg kg(-1) day(-1)). After 18 weeks of treatment, the rabbits were killed and the thoracic aorta, proximal coronary and mesenteric (5th branch) arteries were isolated, cleaned off and mounted in an organ bath. Trandolapril had no significant effect on plasma cholesterol, high density lipoprotein (HDL) or low density lipoprotein (LDL). Despite the lack of effect of the drug on the above-mentioned parameters, treatment with trandolapril improved endothelium-dependent relaxation induced by acetylcholine in aortic and mesenteric rings from hypercholesterolemic rabbits treated with trandolapril. The relaxation induced by 10(-5) M acetylcholine were 65.0+/-4.0%; 24. 0+/-9.4% (P<0.01, n=10) and 51.3+/-7.0% (P<0.01, n=10) in aortic rings from Groups 0, 1 and 2, respectively, and 50.0+/-12.0%; 10. 1+/-10.0% (P<0.01, n=10); 61.0+/-9.7% (P<0.01, n=10) in small mesenteric rings from Groups 0, 1 and 2, respectively. In addition, trandolapril treatment improved the increase in serotonin-induced contraction in proximal coronary arteries with respect to the hypercholesterolemic group. On the other hand, we did not find any differences among the group in endothelium-independent relaxation induced by sodium nitroprusside. These results provide evidence that trandolapril restores endothelium-dependent relaxation in hypercholesterolemic rabbit-isolated arteries. These data suggest that trandolapril might have beneficial action in the prevention of vascular alteration involved in atherosclerosis.     

Modulation of vascular reactivity by vasoactive peptides in aortic rings from hypercholesterolemic rabbits.

The effect of moderate elevation in serum cholesterol on vascular reactivity to epidermal growth factor (EGF), endothelin (ET-1) and thrombin, vasoactive peptides present at sites of vascular injury, was examined in isolated aortic rings from rabbits fed either a casein-rich or a control diet for 10-12 weeks. In rings from hypercholesterolemic rabbits, development of maximal isometric tension to all peptide agonists was increased 22 +/- 0.6% while the EC50 for contraction was decreased. Vasorelaxant responses to nitroprusside, an endothelium-independent dilator, were largely intact, while those to A231897, an endothelium-dependent agent, were attenuated. These data suggest that elevation in serum cholesterol in the absence of atherosclerotic lesions is sufficient to increase vascular reactivity to peptide vasoactive mediators, an effect which may predispose arteries to vasospasm.     

氯沙坦和卡托普利对高脂饮食兔动脉粥样硬化形成和纤溶功能的影响

目的 :探讨氯沙坦和卡托普利对高脂饮食家兔动脉粥样硬化形成和纤溶功能的影响及机制。方法 :健康雄性家兔 4 0只随机分为 4组 :A组予普通饲料、B组予 1%高胆固醇饲料、C组和D组进食同B组 ,分别予氯沙坦和卡托普利灌胃。 12wk后取血检测各项生化指标 ,处死动物 ,制作标本 ,观察主动脉粥样斑块形成情况和血管内膜、中膜的组织形态学改变及内膜的超微结构 ;检测血管组织的内皮素 (ET 1)水平。结果 :B组的血脂和ET 1水平较A组明显增高 ,斑块形成明显 ,血浆t PA活性降低、PAI 1活性增高。氯沙坦的干预不影响血脂水平 ,但可减小斑块面积 ,降低ET 1,改善t PA和PAI 1活性 ;D组除ET 1外的各项指标与C组无统计学差异。C组和D组内皮损伤明显轻于B组。结论 :氯沙坦和卡托普利均能改善高脂血症家兔的内皮纤溶功能 ,减轻粥样斑块形成。     

The effects of probucol on the progression of atherosclerosis in mature Watanabe heritable hyperlipidaemic rabbits.

1. Probucol was administered to mature Watanabe heritable hyperlipidaemic (WHHL) rabbits (approximately 9 months old). Groups of WHHL rabbits were randomly selected and treated as follows: Group 1 killed at 9 months (n = 9); Group II placed on sham-treated diet at 9 months and followed for 6 months (n = 8); Group III placed on probucol at 9 months and followed for 6 months (n = 8). Probucol was administered by mixing 1% wt/wt drug with standard laboratory diet. 2. Plasma concentrations of probucol increased to 93 +/- 11 micrograms ml-1 in Group III during the initial 2 weeks and increased further to 149 +/- 24 micrograms ml-1 at the end of the treatment period. 3. Plasma concentrations of total cholesterol, unesterified cholesterol and phospholipids were significantly reduced overall by probucol, while triglycerides were not affected. 4. No statistically significant differences were observed in the presence of oxidized products in low density lipoproteins (LDL) isolated from plasma of controls compared to probucol-treated rabbits. However, LDL from probucol-treated animals was resistant to oxidation in the presence of Cu2+ (3 microM). 5. Group I had aortic atherosclerosis covering 70 +/- 5% of intimal area of thoracic aortae, that increased to 91 +/- 3% in Group II. This was associated with cholesterol contents of aortae increasing from 1.4 +/- 0.2 microgram mg-1 in Group I to 2.7 +/- 0.3 microgram mg-1 in Group II. Probucol administration did not produce a statistically significant reduction of atherosclerotic lesion area (78 +/- 7%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced histamine-mediated contraction of rabbit penile dorsal artery in diet-induced hypercholesterolemia

The present study was designed to establish whether penile dorsal arteries isolated from rabbits fed a high cholesterol diet show an enhanced contractile and/or impaired vasodilator response to histamine, and to characterize the histamine receptor subtype involved through in vitro isometric techniques. New Zealand White rabbits were fed a normal diet or a 1% cholesterol diet for 16 weeks. Arteries from cholesterol-fed rabbits retained the ability to relax in response to acetylcholine, whereas histamine and noradrenaline induced a greater contraction response compared to that observed in controls. In both groups, histamine-induced contraction was unaffected by the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), its precursor L-arginine or the cyclooxygenase inhibitor indomethacin. Treatment of arterial rings in the control and hypercholesterolemia groups with the H1 receptor antagonist, mepyramine, unmasked a vasodilation response to histamine. This was followed by contraction at higher concentrations showing a leftward displacement of the histamine curve compared to controls. The histamine receptor that induced contraction in preparations from the hypercholesterolemic animals was of the H1 subtype, whereas the receptor involved in histamine-induced relaxation was H2. The affinity of histamine receptor agonists was comparable to their effects in control animals, and receptor antagonists showed the same potency in both groups. Our findings indicate a preserved endothelial function and enhanced contraction in response to histamine in penile dorsal arteries, probably due to a change in the sensitivity of the contractile machinery of smooth muscle but not a mechanism mediated by a receptor.     

氯沙坦抑制球囊成形术后兔血管内膜的增殖

目的 :探讨氯沙坦对球囊成形术后兔血管内膜增殖的影响。方法 :将 2 4只新西兰兔随机分为三组 :对照组、模型组及氯沙坦组。后两组持续给予 1.5 %高胆固醇喂养 ,实验初始行腹主动脉内膜剥脱术 ,8周后对狭窄部位行球囊成形术 ,氯沙坦组于球囊成形术前 1周开始口服氯沙坦 10 m g/ (kg· d)。 12周末取腹主动脉行病理形态学观察。结果 :氯沙坦组内膜厚度 (IT)减少 6 5 % ,内膜面积 (IA )减少 34% ,内膜厚度比中膜厚度 (IT/ MT)减少 32 % ,内膜面积比中膜面积 (IA/ MA)减少 2 8% (P<0 .0 1)。结论 :氯沙坦在不影响血脂的情况下明显抑制血管损伤后内膜增殖     

厄贝沙坦、氯沙坦对兔体内环孢素A药动学的影响

目的:研究厄贝沙坦、氯沙坦对家兔体内环孢素A(CsA)药动学的影响。方法:12只家兔随机分成2组,每组6只。每组采用自身对照法,分别测定合用厄贝沙坦、氯沙坦前、后CsA的血药浓度,并对主要药动学参数进行比较。结果:与合用前比较,合用厄贝沙坦、氯沙坦后CsA的Cmax均显著升高(P<0.01),AUC0～24均显著增加(P<0.01),血浆清除率、表观分布容积均显著降低(P<0.05或P<0.01),其余药动学参数无显著性变化。结论:合用厄贝沙坦、氯沙坦后可升高CsA的血药浓度,临床上其与CsA合用需监测CsA的血药浓度,以保证治疗的安全有效。     

The effect of procyanidolic oligomers on the composition of normal and hypercholesterolemic rabbit aortas

Rabbits were fed with normal (group 1 and 2) and cholesterol rich diets (group 3 and 4) concomitantly to a daily peroral administration of 50 mg/kg procyanidolic oligomers (PCO) to groups 2 and 4. After 10 weeks, the cholesterol content of the blood serum and the excised aortic intima-media were significantly higher in groups 3 and 4 than in groups 1 and 2.The DNA, hydroxyproline, uronic acid contents were similar in aortic dry weight basis in all four groups.The intima-media samples were extracted successively with 0.15 M NaCl, 0.02 M sodium phosphate pH 7.4 (NaCl extract) and with 4M guanidinium chloride, 0.05 M sodium acetate pH 5.8 prior (G1 extract) and following (G2 extract) hydrolysis of the collagen with collagenase.The cholesterol contents of G1 extracts were higher in groups 2 and 4 than in groups 1 and 3.The cholesterol content of aortic elastin increased with cholesterol feeding (group 3). With simultaneous administration of cholesterol and PCO the cholesterol content of aortic elastin in group 4 was significantly lower than in group 3.The uronic acid contents increased in G1 extracts and in the collagenase digest with PCO treatment of both normal and hypercholesterolemic rabbits. The ratio of dermatan-sulphate to chondroitinsulphate decreased with hypercholesterolemia (group 3) and with PCO (group 2 and 4). The parallelism between increased cholesterol and uronic acid contents and modified glycosaminoglycan composition in Gl extract, indicate that the interaction of cholesterol with macromolecules of the aorta can be modulated by PCO. This drug modifies the extractibility of aortic cholesterol and glycosaminoglycans and reduces the association of cholesterol to elastin.     

不同浓度依托咪酯对内毒素孵育前后兔离体肺、体动脉环张力的影响

目的研究不同浓度依托咪酯(Etomidate,Eto)对内毒素(Lipopolysaccharide,LPS)孵育前后的离体兔肺动脉和主动脉环张力的影响,为临床脓毒性休克麻醉药选择提供依据。方法制备兔离体肺动脉环和主动脉环,随机分为4组:正常肺动脉环组、LPS孵育后肺动脉环组、正常主动脉环组、LPS孵育后主动脉环组,观察Eto在去氧肾上腺素预收缩动脉环的作用下,Eto剂量分别为1.0、2.0、10.0μmol/L时,对4组肺动脉和主动脉环的张力作用。结果 Eto的给药量为1.0μmol/L时,LPS孵育前后肺、主动脉环张力无明显变化(P>0.05);2.0μmol/L时,正常肺、主动脉环和LPS孵育后主动脉环张力明显上升(P<0.05);10.0μmol/L时,LPS孵育的肺、主动脉环的张力较正常肺、主动脉环明显下降(P<0.05)。结论低浓度Eto收缩机制占主导,但随着浓度增加,Eto引起内毒素孵育后肺动脉舒张的程度比体动脉更明显,可能与高浓度Eto抑制血管收缩功能有关。     

Endothelial dysfunction and improvement of the angiotensin II-reactivity in hypercholesterolemic rabbits: role of cyclooxygenase metabolites

The aim of this paper was to study the effect of high cholesterol diet on endothelial function and vascular reactivity to angiotensin II and to test the role of vasoconstrictor cyclooxygenase metabolites in this experimental condition. Rabbits were fed with either normal chow or a diet containing 1% cholesterol for 6-7-week. Isometric contractions were measured in rubbed or unrubbed aortic rings. Arteries were contracted with noradrenaline and then exposed to one cumulative dose-response curve to acetylcholine in absence (control) or in presence of indomethacin, (N-[2-cyvlohexyloxy)-4-nitrophenyl]-methanesulfonamide) (NS 398) or 4-hydroxy-2,2,6,6-tetraethylpiperidine-N-oxyl (tempol). After washing the arteries, one cumulative dose-response curve to angiotensin II was constructed in absence or presence of indomethacin, NS 398, [1S-[1 alpha,2 beta (5Z),3 beta,4 alpha]-7-[3-[[2-[(phenylamino) carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1] hept-2-yl]-5-heptenoic acid (SQ29548) or 17-octadecynoic acid (17-ODYA). In other group, resting potential was recorded in basal and angiotensin II-stimulated conditions. Indomethacin, NS 398 or 17-ODYA were added to the bath before angiotensin II-stimulation. Rabbits fed on a diet enriched with cholesterol showed higher plasma levels of total cholesterol and LDL. Hypercholesterolemic diet impaired acetylcholine relaxation. Indomethacin normalized endothelium-dependent relaxation whereas NS 398 and tempol had no effect on this phenomenon. Angiotensin II-reactivity was increased in endothelium intact hypercholesterolemic aortic rings and indomethacin, SQ29548 or 17-ODYA blocked this effect. The resting potential of unrubbed hypercholesterolemic arteries was significantly less negative to control after angiotensin II-stimulation. 17-ODYA but not indomethacin prevented angiotensin II-depolarization. High cholesterol diet caused endothelial dysfunction and increased the angiotensin II-reactivity. Both effects were cyclooxygenase1-dependent. Deficit in the NO-production might improve 20-hydroxyeicosatrienoic acid availability, which induces depolarization and angiotensin II-sensitization. In addition, 20-hydroxyeicosatrienoic acid would be metabolized by cyclooxygenase1 to 20-endoperoxides which act through thromboxane A(2)/prostaglandin H(2) receptors contributing to angiotensin II-reactivity increase.     

Effect of atorvastatin on tumor necrosis factor alpha serum concentration and mRNA expression of adipose in hypercholesterolemic rabbits

Tumor necrosis factor alpha (TNFalpha) is an inflammatory cytokine involved in atherogenesis. Adipose tissue is an important source of endogenous TNFalpha production. The aim of this study was to evaluate the effect of atorvastatin on TNFalpha serum concentration and mRNA expressions of subcutaneous adipose in hypercholesterolemic rabbits. Sixteen rabbits fed with a high-cholesterol diet for 8 weeks were randomly divided into 2 groups: (1) the high-cholesterol group (n=8) was maintained on a high-cholesterol diet for 6 weeks; (2) the atorvastatin group (n=8) had the same high-cholesterol diet plus atorvastatin (2.5 mg/kg/d) for 6 weeks. A control group (n=5) was fed with a normal diet for 14 weeks. Subcutaneous adipose was collected for mRNA analysis. Additionally, the direct effect of atorvastatin on TNFalpha release and mRNA expression was assayed in primary rabbit adipocytes. TNFalpha levels in serum and adipocyte culture supernatant were measured by ELISA. RT-PCR was used to evaluate TNFalpha mRNA expression in adipose and adipocytes. Serum TNFalpha concentration was significantly associated with serum total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) (both P<0.01). Compared with the control group, rabbits fed with a high-cholesterol diet showed higher levels of TNFalpha serum concentration and mRNA expression of adipose, both of which were significantly reduced by atorvastatin treatment (both P<0.05). TNFalpha mRNA expressions of adipose were significantly correlated with circulating TNFalpha levels among the 3 groups (r=0.51, P<0.05). Atorvastatin dose-dependently inhibited lipopolysaccharide (LPS)-induced TNFalpha secretion and mRNA expression in cultured adipocytes. In conclusion, atorvastatin can directly inhibit TNFalpha expression and secretion in adipocytes. Atorvastatin reduced TNFalpha serum concentration in hypercholesterolemic rabbits, which might be because of its cholesterol-lowering effect and direct inhibition of TNFalpha expression in adipose.     

Improvement of vascular function by chronic administration of a cyclo-oxygenase inhibitor in cholesterol-fed rabbits

1. Atherosclerotic cardio- and cerebrovascular disease is a leading cause of mortality in Western countries. Aspirin-like drugs are widely used to prevent and treat these occlusive cardio- and cerebrovascular diseases. The beneficial effects of these drugs have been largely attributed to inhibition of platelet cyclo-oxygenase activity and thromboxane (TX) A2 production. We investigated the effect of an aspirin-like drug, namely indomethacin, on endothelial function, plaque and platelet aggregation and the formation of vasoactive substances during the development of atherosclerosis in cholesterol-fed rabbits. 2. Rabbits were fed 1% cholesterol (n = 8), 1% cholesterol plus 25 mg/day indomethacin (n = 8) or normal rabbit chow (control group; n = 8) for 12 weeks. Urinary excretion rates of 2,3-dinor-TXB2, 6-keto-prostaglandin (PG) F1alpha, 8-iso-PGF2alpha and nitrate were analysed at the beginning of dietary intervention and at 4 weekly intervals thereafter. At the end of the study period, platelet aggregation, aortic plaque formation and endothelium-dependent and -independent vascular functions of isolated aortic rings ex vivo were assessed. 3. Compared with control, in the cholesterol-fed group, urinary 2,3-dinor-TXB2, 6-keto-PGF1alpha and 8-iso-PGF2alpha excretion and platelet aggregation were significantly increased (P < 0.05), but urinary excretion of nitrate was decreased (P < 0.05). Treatment with indomethacin significantly reduced platelet aggregation, urinary 2,3-dinor-TXB2, 6-keto-PGF1alpha and 8-iso-PGF2alpha excretion (P < 0.05 vs the cholesterol-fed group) and attenuated the reduction in urinary nitrate excretion. 4. Cholesterol feeding progressively increased aortic intimal thickening and impaired endothelium-dependent vasodilator function (P < 0.05 vs control), whereas indomethacin partially prevented aortic plaque formation and restored endothelium-dependent vasodilation (P < 0.05 vs the cholesterol-fed group). 5. The present study demonstrates that indomethacin reduces the progression of atherosclerotic lesions and improves endothelium-mediated vascular responses ex vivo in cholesterol-fed rabbits. The beneficial effects of indomethacin may be due to its ability to prevent the elevation of platelet aggregation, TXA2 (measured as urinary 2,3-dinor-TXB2 excretion) and 8-iso-PGF2alpha formation and to retard the decrease in endogenous nitric oxide synthesis (assessed as urinary excretion of nitrate). Despite indomethacin treatment leading to the suppression of prostacyclin biosynthesis (assessed as urinary 6-keto-PGF1alpha excretion), according to our data, indomethacin appears to preserve endothelial function.     

L-精氨酸对高脂血症家兔主动脉和冠状动脉病变组织胆固醇含量的影响

目的探讨Ｌ－精氨酸对高脂血症家兔主动脉和冠状动脉病变组织胆固醇含量的影响。方法选择健康♂新西兰白兔１４４只（体重２．０～２．２ｋｇ），分为空白对照组、硝苯吡啶组、消心痛组、Ｌ－精氨酸组和高胆固醇组。预防性给药９０ｄ，治疗性给药是在预防性给药的基础上停喂胆固醇，其余处理因素不变，再观察９０ｄ。结果喂养１，１．５，２ｇ·ｋｇ－１·ｄ－１Ｌ－精氨酸均能减少高胆固醇血症所诱导的主动脉和冠状动脉病变组织胆固醇含量。不同剂量的硝苯吡啶和消心痛虽能减少高胆固醇血症所诱导的主动脉和冠状动脉病变组织胆固醇含量，但Ｌ－精氨酸降低家兔主动脉和冠状动脉病变组织胆固醇含量的效果优于硝苯吡啶及消心痛。结论Ｌ－精氨酸有显著的抗实验性家兔动脉粥样硬化的作用，硝苯吡啶和消心痛也有类似作用，但效果不及Ｌ－精氨酸     

吡格列酮对高脂饮食兔主动脉血管内皮细胞黏附分子-1表达的影响

目的探讨吡格列酮对高脂饮食下兔主动脉血管内皮细胞黏附分子(VCAM)-1表达的影响。方法设立正常饮食、高脂饮食及高脂饮食加吡格列酮干预3组,通过比较主动脉病理形态学改变、血脂的变化、VCAM-1分子的表达进行研究,采用苏木素-伊红染色用于主动脉病理形态学观察,采用免疫组织化学检测兔主动脉上VCAM-1的表达。结果吡格列酮能减轻高脂饮食所致的内膜增厚和平滑肌增生。吡格列酮还能明显升高高密度脂蛋白胆固醇(HDL),对总胆固醇(TC)、低密度脂蛋白胆固醇(LDL)、甘油三酯(TG)无明显影响。高脂饮食刺激兔主动脉VCAM-1的表达增加,吡格列酮能显著减轻这种作用(0.78±0.16vs0.42±0.11,P<0.01)。结论吡格列酮能减轻高脂饮食兔主动脉VCAM-1的表达,其作用的机制可能与其干扰核转录因子有关。     

VASOCONSTRICTOR RESPONSES TO POLYMORPHONUCLEAR LEUCOCYTES FROM ATHEROSCLEROTIC RABBITS

1. The vascular contractile effects of polymorphonuclear leucocytes (PMN) isolated from control rabbits and from rabbits made atherosclerotic by 1% cholesterol feeding for 8 weeks were examined. 2. Rings of control rabbit thoracic aorta with or without endothelium were mounted at 2g tension in 10 mL organ baths and were submaximally contracted by phenylephrine (0.1 μmol/L). After 30 min incubation at 37° C, the supernatant of PMN (5X10⁷/mL, in Tyrode solution containing 0.25% bovine serum albumin) was obtained by centrifugation for addition to the vascular preparation. 3. Control PMN supernatant (443 μL) caused contraction (0.58±0.15g, n= 11) of phenylephrine-contracted aortic rings, which was prevented by removal of the endothelium (0.11 ± 0.07g, n= 5, P<0.05). However, the control PMN supernatant had no contractile effect on aortic rings at resting tension (0.00 ± 0.00g, n= 8). 4. By comparison, atherosclerotic PMN supernatant (443 μL) caused a significantly greater contraction of the aortic rings (1.41± 0.13g, n= 9, P<0.05 vs control PMN supernatant) that was only partly inhibited by removal of the endothelium (0.45 ± 0.20g, n= 9, P<0.05). Moreover, PMN supernatants from four of seven atherosclerotic rabbits contracted aortic rings at resting tension (3.5 ±1.4g, n= 7). 5. These results suggest that the release of a stable vasoconstrictor substance(s) by PMN is enhanced under conditions of atherosclerosis. The constrictor action of this substance(s) appears to be greater in the presence of a functional endothelium, and part of its action may involve inactivation of endothelium-derived nitric oxide.     

Probucol attenuates the development of aortic atherosclerosis in cholesterol-fed rabbits.

1. Probucol was administered to rabbits fed a cholesterol-enriched (2% wt/wt) diet to determine potential anti-atherogenic effects in a preparation in which the disease process is due to elevated plasma concentrations of cholesterol ester-rich very low density lipoproteins (CER-VLDL). 2. Probucol was supplemented to the diet at 1% wt/wt which resulted in plasma concentrations rising steadily to 53 +/- 8 micrograms ml-1 after 14 days, with no significant changes during continued administration. Dietary consumption and body weight gains were comparable in the drug-treated and control groups during the observation period. 3. Probucol treatment did not significantly affect plasma concentrations of total cholesterol, unesterified cholesterol, triglycerides or phospholipids. 4. The concentration of CER-VLDL in plasma and its physicochemical characteristics were not significantly changed during administration of probucol. CER-VLDL from both control and probucol-treated animals was a potent stimulant of the augmentation of the intracellular incorporation of [3H]-oleate into cholesteryl-[3H]-oleate in cultured macrophages. 5. Despite the lack of effect of probucol on concentrations of plasma lipids and the cell interaction characteristics of CER-VLDL, administration of the drug markedly decreased the extent of intimal aortic surface area covered by grossly discernible atherosclerotic lesions from 55.6 +/- 11.8% to 11.6 +/- 1.9% in thoracic sections, and from 49.1 +/- 10.2% to 7.2 +/- 0.4% in abdominal sections. Furthermore, probucol treatment significantly reduced the deposition of total cholesterol in vascular tissue. 6. Probucol reduced the extent of aortic atherosclerosis produced by diet-induced hypercholesterolemia in rabbits. This reduction occurred in the absence of any significant change in the characteristics of plasma lipoproteins that were determined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Naringin has an antiatherogenic effect with the inhibition of intercellular adhesion molecule-1 in hypercholesterolemic rabbits.

Naringin, a bioflavonoid found in citrus fruit peel, is known to have an antioxidative effect, but its effect on atherosclerosis has not been studied. This study evaluated the effect of naringin on blood lipid levels and aortic fatty streaks, and its action mechanism in hypercholesterolemic rabbits. Male New Zealand white rabbits were fed a 0.25% cholesterol diet and divided into an untreated group (n = 4), a naringin-treated group (n = 5; 500 mg/kg per day), and a lovastatin-treated group (n = 5; 20 mg/kg per day). After 8 weeks, blood was sampled and analyzed biochemically. Aorta and liver were harvested and examined histologically. Cholesterol level in rabbits fed the 0.25% cholesterol diet reached 17 times normal and decreased in the rabbits fed naringin and lovastatin, whose effects were not statistically significant (p > 0.05). However, both naringin and lovastatin effectively decreased the area of fatty streak in thoracic aorta on macroscopic analysis (p < 0.05) and significantly reduced subintimal foam cell infiltration on microscopic morphometry (p < 0.05). These foam cells were macrophages on immunohistochemical analysis. Naringin treatment inhibited hypercholesterolemia-induced intercellular adhesion molecule-1 (ICAM-1) expression on endothelial cells. Hypercholesterolemia caused fatty liver and elevation of liver enzymes, which was prevented by naringin but not by lovastatin. Naringin significantly reduced fatty streak formation and neointimal macrophage infiltration and also inhibited the expression of ICAM-1 in endothelial cells, suggesting that suppression of ICAM-1 contributed to the antiatherogenic effect. Naringin, unlike lovastatin, has a hepatoprotective action.     

罗格列酮联合阿托伐他汀对高胆固醇血症兔主动脉斑块面积和TNF-α的影响

目的：观察罗格列酮和阿托伐他汀单独或联合应用对高胆固醇血症兔主动脉斑块面积和TNF-α的影响。方法：24只雄性新西兰大白兔高胆固醇饮食8周后,随机加喂淀粉（淀粉组,n=6）或阿托伐他汀（阿托伐他汀组,5mg·kg-1·d-1,n=6）或罗格列酮钠（罗格列酮组,3mg·kg-1·d-1,n=6）或罗格列酮钠联合阿托伐他汀（联合组,阿托伐他汀钙5mg·kg-1·d-1、罗格列酮3mg·kg-1·d-1,n=6）喂养4周。以普通饲料喂养兔作为正常对照（对照组,n=6）。各组兔共喂养12周后,取兔主动脉测定内膜斑块面积,同时分离外周血单核细胞培养24h,采用酶联免疫吸附测定法检测血浆和单核细胞细胞培养上清液TNF-α。结果：与对照组相比,高胆固醇饮食各组兔血浆和外周血单核细胞1TNF-α水平升高（均P〈0．01）;与淀粉组相比,阿托伐他汀和罗格列酮体内干预都能降低高胆固醇血症兔主动脉斑块面积百分数、血浆和外周血单核细胞TNF-α水平,且二者联合干预降低程度更显著（P均〈0．01）;兔主动脉斑块面积与血浆／外周血单核细胞TNF-α水平呈显著正相关（均P〈0．01）。结论：阿托伐他汀和罗格列酮可能通过抑制外周血单核细胞分泌TNF-α发挥抗动脉粥样硬化（AS）作用,且二者联合应用效果更佳。     

Anti-hyperlipidemic and anti-atherosclerotic effects of Pinus eldarica Medw. nut in hypercholesterolemic rabbits

Background

Previous studies suggest that chemical constituents present in Pinus eldarica Medw (P. eldarica) nut possess antioxidant properties that may positively influence lipid profile.The present study was conducted to evaluate the efficacy of P. eldarica nut on the experimental atherosclerosis development in hypercholesterolemic rabbits.

Methods

Forty male 6 months old white New Zealand rabbits (1.8–2 kg) were randomly assigned into five equal groups. One group was kept as control (normal) group, fed on standard rabbit diet and other 4 groups were fed on high cholesterol diet (HCD). Out of four HCD groups one group was kept as control (HCD) and other three groups were treated with different doses (50, 100 and 200 mg/kg/day) of P. eldarica nut for 8 weeks. Percentage of aortic wall area changes as indication of atherosclerosis development and fasting blood cholesterol, LDL, HDL and triglyceride levels were determined in all groups.

Results

The results indicate that fasting blood cholesterol and aortic atherosclerotic involvements in 200 mg/kg/day and 100 mg/kg/day P. eldarica nut extract treated groups significantly decreased as compared to the high cholesterol-diet control group.

Conclusion

P. eldarica nut lowers blood cholesterol level and aortic atherosclerotic involvement in hypercholesterolemic rabbits.     

Long-term low-dose treatment with reserpine of cholesterol-fed rabbits reduces cholesterol in plasma,non-high density lipoproteins and arterial walls

The effects of long-term low-dose treatment with reserpine on plasma lipoproteins and arterial cholesterol were determined in cholesterol-fed rabbits. Hepatic low-density lipoprotein (LDL) receptors; uptake of LDL by liver, heart, and kidneys; plasma fibrinogen; blood pressure; and heart rate were also determined. Reserpine at 43 microg/kg. d was continuously infused subcutaneously via implanted minipumps for 6 weeks into conscious unrestrained male New Zealand White rabbits (n = 5) fed a 0.2% cholesterol-enriched diet. Compared with controls, reserpine (n = 4) significantly reduced the elevated levels of plasma total cholesterol and esterified and unesterified cholesterol throughout the study, and at 6 weeks of treatment these reductions were 42, 41, and 49%, respectively. The increased cholesterol in the aortic walls (n = 5) produced by the atherogenic diet was reduced by 73% (p < 0.004) and 125I-tyramine cellobiose-labeled LDL by 67 to 86% (0.05 < p <0.004), respectively. The aortic intimal-medial thickness ratio was reduced by 70%. The decrease in elevated plasma total cholesterol was mainly due to cholesterol reductions in both LDL (41%) and non-high density lipoprotein (HDL) of density < 1.019 g/ml (51%). HDL cholesterol and triglyceride levels were unchanged. Reserpine had no significant effects on the clearance of 125I-tyramine cellobiose-LDL from plasma and there was a trend towards an increase in hepatic LDL receptor expression. Heart rate was decreased by 28%. There were no significant effects on blood pressure, liver and heart lipids, hematocrit, or plasma fibrinogen. The results suggest that treatment of cholesterol-fed rabbits with reserpine at a low dose over a long period prevents increases in plasma atherogenic lipoproteins. Reserpine decreases the cholesterol in aortic walls and the intima-media thickness ratio. This anti-atherosclerotic effect of reserpine may have therapeutic implication.