Normocholesterolemic Rats Research Articles

ANTIHYPERCHOLESTEROLEMIC AND ANTIATHEROGENIC POTENTIAL OF AQUEOUS EXTRACT OF ADANSONIA DIGITATA STEM BARK INDUCED BY HEATED PALM OIL SUPPLEMENTED WITH EGG YOLK IN RAT

Objective: Poor control of hypercholesterolemia which mediated by overproduction of reactive oxygen species and endothelial dysfunction leads to atherosclerosis. The present study aimed to investigate the antihypercholesterolemic and anti-atherogenic effects of Adansonia digitata (AD) in heated palm oil/cholesterol supplemented with egg yolk in rat.
 Methods: Quantitative phytochemical screening of aqueous extract of A. digitata was carried out to identify the phytoconstituents. In vitro and in vivo antioxidant potential was evaluated. The antihypercholesterolemic and anti-atherosclerosis activity of A. digitata was evaluated by inducing hypercholesterolemia in rats with heated palm oil/cholesterol diet supplemented with egg yolk for 10 w. At the end of the induction period, animals were divided into 5 groups of 8 rats each after 6 w of induction: Group I (normocholesterolemic rat, NCR), Group II (hypercholesterolemia rat, HCR), Group III (Atorvastatin 2 mg/kg), Groups IV (AD. 100 mg/kg) and V (AD. 200 mg/kg). Hemodynamic parameters, lipid profile, atherogenic indices and oxidative stress markers were evaluated.
 Results: Adansonia digitata significantly reduced the systolic arterial blood pressure (SBP), diastolic arterial blood pressure (DBP), pulsatile pressure (PP) and heart rate compared to the hypercholesterolemic group. Plant extract reveal important flavonoids and phenolic contents and has significant in vivo antioxidant efficacy. The higher dose (200 mg/kg) of the extract significantly reduced in the level of total cholesterol by 27.29 %, triglycerides by 27.60 % and the LDL-c by 36.04 % meanwhile the HDL-c increased by 277.47 % when compared to 5HPOC treated group. Atorvastatin (2 mg/kg) administered in addition to 5HPOC significantly improved in lipid profile as compared to untreated rats. Furthermore, the histopathological examination of aorta of 5HPOC-treated rats indicated that the aqueous extract of A. digitata significantly attenuated atherosclerosis lesions.
 Conclusion: The aqueous extract of A. digitata possessed antihypercholesterolemic and anti-atherogenic effects via modulation overproduction of reactive oxygen species and endothelial dysfunction.

Anti-Hypercholesterolemic and Anti-Atherogenic Potential of Aqueous Extract of Dansonia Digitata Stem Bark Induced By Heated Palm Oil Supplemented With Egg in Rat

Aim: To investigate the antihypercholesterolemic and anti-atherogenic effects of Adansonia digitata (AD.) in in heated palm oil/cholesterol supplemented with egg in rat. Methods: Quantitative phytochemical screening of aqueous extract of A. digitata was carried out to identify the phytoconstituents. In vitro and in vivo antioxidant potential was evaluated. The antihypercholesterolemic and anti-atherosclerosis activity of A. digitata was evaluated by inducing hypercholesterolemia in rats with heated palm oil/cholesterol diet supplemented with egg for 10 weeks. At the end of induction period, animals were divided into 5 groups of 8 rats each after 6 weeks of induction: Group I (normocholesterolemic rat, NCR), Group II (hypercholesterolemia rat, HCR), Group III (Atorvastatin 2 mg/kg), Groups IV (AD. 100 mg/kg) and V (AD. 200 mg/kg). Hemodynamic parameters, lipid profile, atherogenic indices and oxidative stress markers were evaluated. Results: A digitata significantly reduced the systolic arterial blood pressure (SBP), diastolic arterial blood pressure (DBP), pulsatile pressure (PP) and heart rate. Plant extract reveal important flavonoids and phenolic contents and has significant in vitro and in vivo antioxidant efficacy. Both doses 100 and 200 mg/kg of A. digitata or atorvastatin significantly attenuated the lipid levels, atherogenic indices and histological abnormalities and significantly (p < 0.01) increased increase the high-density lipoprotein cholesterol (HDL-c) level. Conclusion: The aqueous extract of A. digitata possessed antihypercholesterolemic and anti-atherogenic effects via modulation overproduction of reactive oxygen species and endothelial dysfunction.

Redox regulation of hemodynamics response to diadenosine tetraphosphate an agonist of P2 receptors and renal function in diet-induced hypercholesterolemic rats.

Hypercholesterolemia and oxidative stress may lead to disturbances in the renal microvasculature in response to vasoactive agents, including P2 receptors (P2R) agonists. We investigated the renal microvascular response to diadenosine tetraphosphate (Ap4A), an agonist of P2R, in diet‐induced hypercholesteremic rats over 28 days, supplemented in the last 10 days with tempol (2 mM) or DL‐buthionine‐(S,R)‐sulfoximine (BSO, 20 mM) in the drinking water. Using laser Doppler flowmetry, renal blood perfusion in the cortex and medulla (CBP, MBP) was measured during the infusion of Ap4A. This induced a biphasic response in the CBP: a phase of rapid decrease was followed by one of rapid increase extended for 30 min in both the normocholesterolemic and hypercholesterolemic rats. The phase of decreased CBP was not affected by tempol or BSO in either group. Early and extended increases in CBP were prevented by tempol in the hypercholesterolemia rats, while, in the normocholesterolemic rats, only the extended increase in CBP was affected by tempol; BSO prevented extended increase in CBP in normocholesterolemic rats. MBP response is not affected by hypercholesterolemia. The hypercholesterolemic rats were characterized by increased urinary albumin and 8‐isoPGF2α excretion. Moreover, BSO increased the urinary excretion of nephrin in the hypercholesterolemic rats but, similar to tempol, did not affect the excretion of albumin in their urine. The results suggest the important role of redox balance in the extracellular nucleotide regulation of the renal vasculature and glomerular injury in hypercholesterolemia.

Cholesterol antagonism of alcohol inhibition of smooth muscle BK channel requires cell integrity and involves a protein kinase C-dependent mechanism(s)

Alcohol constricts cerebral arteries via inhibition of voltage/calcium-gated, large conductance potassium (BK) channels in vascular myocytes. Using a rat model of high-cholesterol (high-CLR) diet and CLR enrichment of cerebral arteries in vitro, we recently showed that CLR protected against alcohol-induced constriction of cerebral arteries. The subcellular mechanism(s) underlying CLR protection against alcohol-induced constriction of the artery is unclear. Here we use a rat model of high-CLR diet and patch-clamp recording of BK channels in inside-out patches from cerebral artery myocytes to demonstrate that this diet antagonizes inhibition of BK currents by 50 mM ethanol. High-CLR-driven protection against alcohol inhibition of BK currents is reversed following CLR depletion in vitro. Similar to CLR accumulation in vivo, pre-incubation of arterial myocytes from normocholesterolemic rats in CLR-enriching media in vitro protects against alcohol-induced inhibition of BK current. However, application of CLR-enriching media to cell-free membrane patches does not protect against the alcohol effect. These different outcomes point to the involvement of cell signaling in CLR-alcohol interaction on BK channels. Incubation of myocytes with the PKC activators phorbol 12-myristate 13-acetate or 1,2-dioctanoyl-sn-glycerol, but not with the PKC inhibitor Gouml 6983, prior to patch excision precludes CLR enrichment from antagonizing alcohol action. Thus, PKC activation either disables the CLR target(s) or competes with elevated CLR. Favoring the latter possibility, 1,2-dioctanoyl-sn-glycerol protects against alcohol-induced inhibition of BK currents in patches from myocytes with naïve CLR. Our findings document that CLR antagonism of alcohol-induced BK channel inhibition requires cell integrity and is enabled by a PKC-dependent mechanism(s).

Hypercholesterolemia Interferes with Induction of miR-125b-1-3p in Preconditioned Hearts.

Ischemic preconditioning (IPre) reduces ischemia/reperfusion (I/R) injury in the heart. The non-coding microRNA miR-125b-1-3p has been demonstrated to play a role in the mechanism of IPre. Hypercholesterolemia is known to attenuate the cardioprotective effect of preconditioning; nevertheless, the exact underlying mechanisms are not clear. Here we investigated, whether hypercholesterolemia influences the induction of miR-125b-1-3p by IPre. Male Wistar rats were fed with a rodent chow supplemented with 2% cholesterol and 0.25% sodium-cholate hydrate for 8 weeks to induce high blood cholesterol levels. The hearts of normo- and hypercholesterolemic animals were then isolated and perfused according to Langendorff, and were subjected to 35 min global ischemia and 120 min reperfusion with or without IPre (3 × 5 min I/R cycles applied before index ischemia). IPre significantly reduced infarct size in the hearts of normocholesterolemic rats; however, IPre was ineffective in the hearts of hypercholesterolemic animals. Similarly, miR-125b-1-3p was upregulated by IPre in hearts of normocholesterolemic rats, while in the hearts of hypercholesterolemic animals IPre failed to increase miR-125b-1-3p significantly. Phosphorylation of cardiac Akt, ERK, and STAT3 was not significantly different in any of the groups at the end of reperfusion. Based on these results we propose here that hypercholesterolemia attenuates the upregulation of miR-125b-1-3p by IPre, which seems to be associated with the loss of cardioprotection.

Effects of citrus latifolia extract on dyslipidemia and tissues redox status in rats fed a high-cholesterol diet

PurposeThis study aims to investigate the possible effect of Citrus latifolia (CL) extract on biomarkers of oxidative stress, including lipid peroxidation products in rats fed a high cholesterol dietDesign/methodology/approachHypercholesterolemia was induced by feeding normocholesterolemic rats 1 per cent cholesterol-enriched diet for 15 days. An experimental group (n = 20) was divided into two groups (n = 10) and fed the same diet with or without CL lyophilized aqueous extract (1 per cent) for four weeks. At day 28, ten rats from each group were killed.FindingsTreatment with CL lyophilized aqueous extract compared with the untreated group had decreased plasma total cholesterol (TC) (−36 per cent), triacylglycerols (−48 per cent), isoprostanes values (−74 per cent) and reduced thiobarbituric acid reactive substances in erythrocytes (−21 per cent). However, the supplementation of CL peels in the hypercholesterolemic diet enhanced superoxide dismutase (+69 per cent), glutathione reductase (+30 per cent) and catalase activities (+34 per cent).Originality/valueIn hypercholesterolemic rats, administering CL extract ameliorates dyslipidemia and attenuates lipid peroxidation in tissues. These results suggest that CL could be beneficial in the primary treatment of hypercholesterolemia and oxidative damage caused by a high-cholesterol diet.

Pravastatin Prevents Arrhythmias Induced by Coronary Artery Ischemia/Reperfusion in Anesthetized Normocholesterolemic Rats

Pravastatin Prevents Arrhythmias Induced by Coronary Artery Ischemia/Reperfusion in Anesthetized Normocholesterolemic Rats

The effect of atorvastatin on penile intracavernosal pressure and cavernosal morphology in normocholesterolemic rats.

A debate is open on the effects of lipid-lowering drugs on sexual function. We aimed to investigate the effect of atorvastatin use on penile intracavernosal pressure (ICP) and cavernosal morphology. Fourteen mature male Sprague-Dawley-rats were randomly assigned to either the control group (which received standard food and water ad libitum) or the atorvastatin group (which received standard food, water, and statin) for twelwe weeks. At the end of the study, ICPs were measured with cavernosometry. Penectomy specimens were histologically examined. The following mean values were obtained for the control and atorvastatin groups, respectively: pre-study body weights (350±16.9 g and 331.4±24.9 g); post-study body weights (356±18 g and 368±22.5 g (p>0.05); ICPs at 5 V (5.96±5.16 mmHg and 2.11±1.22 mmHg (p=0.07)); ICPs at 10 V (18.28±14.1 mmHg and 5.56±5.58 mmHg) (p=0.09); testosterone (1.23±0.78 and 0.78±0.58 mmol/dL) (p=0.39); blood glucose (151±22 mg/dL and 168.6±16.2 mg/dL) (p=0.12); triglyceride (93.4±19.8 mg/dL and 52.1±18.6 mg/dL) (p=0.01); total cholesterol (50.2±7.2 mg/dL and 47.7±6.6 mg/dL) (p=0.51); and low-density lipoprotein (LDL) cholesterol (10.0±4.4 mg/dL and 3.5±2.1 mg/dL) (p=0.01). The mean collagen thickness was similar (p=0.09); but the mean elastin thickness increased in the atorvastatin group (p=0.01). The present study showed that the use of atorvastatin reduced the intracavernosal pressure in 10 V stimulation, and minimally decreased testosterone levels in rats, within a short period of time. When statin treatment is considered for its protective properties on cardiovascular system or for its lipid-lowering effect. It should be kept in mind that atorvastatin may also adversely contribute to erectile dysfunction.

Simvastatin Promotes Cardiac Myocyte Relaxation in Association with Phosphorylation of Troponin I

The number of people taking statins is set to increase across the globe due to recent changes in prescription guidelines. For example, half the US population over 40 is now eligible for these drugs, whether they have high serum cholesterol or not. With such development in policy comes a stronger need for understanding statins’ myriad of effects. Surprisingly little is known about possible direct actions of statins on cardiac myocytes, although claims of a direct myocardial toxicity have been made. Here, we determine the impact of simvastatin administration (40 mg/kg/day) for 2 weeks in normocholesterolemic rats on cardiac myocyte contractile function and identify an underlying mechanism. Under basal conditions, statin treatment increased the time to half (t0.5) relaxation without any effect on the magnitude of shortening, or the magnitude/kinetics of the [Ca2+]i transient. Enhanced myocyte lusitropy could be explained by a corresponding increase in phosphorylation of troponin I (TnI) at Ser23,24. Statin treatment increased expression of eNOS and Ser1177 phosphorylated eNOS, decreased expression of the NOS-inhibitory proteins caveolins 1 and 3, and increased (P = 0.06) NO metabolites, consistent with enhanced NO production. It is well-established that NO stimulates protein kinase G, one of the effectors of TnI phosphorylation at Ser23,24. Trends for parallel changes in phospho-TnI, phospho-eNOS and caveolin 1 expression were seen in atrial muscle from patients taking statins. Our data are consistent with a mechanism whereby chronic statin treatment enhances TnI phosphorylation and myocyte lusitropy through increased NO bioavailability. We see no evidence of impaired function with statin treatment; the changes we document at the level of the cardiac myocyte should facilitate diastolic filling and cardiac performance.

AT1 Receptor Modulator Attenuates the Hypercholesterolemia-Induced Impairment of the Myocardial Ischemic Post-Conditioning Benefits

Background and ObjectivesIschemic post-conditioning (PostC) has been demonstrated as a novel strategy to harness nature's protection against myocardial ischemia-reperfusion (I/R). Hypercholesterolemia (HC) has been reported to block the effect of PostC on the heart. Angiotensin II type-1 (AT1) modulators have shown benefits in myocardial ischemia. The present study investigates the effect of a novel inhibitor of AT1, azilsartan in PostC of the heart of normocholesterolemic (NC) and HC rats.Materials and MethodsHC was induced by the administration of high-fat diet to the animals for eight weeks. Isolated Langendorff's perfused NC and HC rat hearts were exposed to global ischemia for 30 min and reperfusion for 120 min. I/R-injury had been assessed by cardiac hemodynamic parameters, myocardial infarct size, release of tumor necrosis factor-alpha troponin I, lactate dehydrogenase, creatine kinase, nitrite in coronary effluent, thiobarbituric acid reactive species, a reduced form of glutathione, superoxide anion, and left ventricle collagen content in normal and HC rat hearts.ResultsAzilsartan post-treatment and six episodes of PostC (10 sec each) afforded cardioprotection against I/R-injury in normal rat hearts. PostC protection against I/R-injury was abolished in HC rat hearts. Azilsartan prevented the HC-mediated impairment of the beneficial effects of PostC in I/R-induced myocardial injury, which was inhibited by L-N5-(1-Iminoethyl)ornithinehydrochloride, a potent inhibitor of endothelial nitric oxide synthase (eNOS).ConclusionAzilsartan treatment has attenuated the HC-induced impairment of beneficial effects of PostC in I/R-injury of rat hearts, by specifically modulating eNOS. Azilsartan may be explored further in I/R-myocardial injury, both in NC and HC conditions, with or without PostC.

Effects of fluvastatin and coenzyme Q10 on skeletal muscle in normo- and hypercholesterolaemic rats

Myalgia and muscle weakness may appreciably contribute to the poor adherence to statin therapy. Although the pathomechanism of statin-induced myopathy is not completely understood, changes in calcium homeostasis and reduced coenzyme Q10 levels are hypothesized to play important roles. In our experiments, fluvastatin and/or coenzyme Q10 was administered chronically to normocholesterolaemic or hypercholaestherolaemic rats, and the modifications of the calcium homeostasis and the strength of their muscles were investigated. While hypercholesterolaemia did not change the frequency of sparks, fluvastatin increased it on muscles both from normocholesterolaemic and from hypercholesterolaemic rats. This effect, however, was not mediated by a chronic modification of the ryanodine receptor as shown by the unchanged ryanodine binding in the latter group. While coenzyme Q10 supplementation significantly reduced the frequency of the spontaneous calcium release events, it did not affect their amplitude and spatial spread in muscles from fluvastatin-treated rats. This indicates that coenzyme Q10 supplementation prevented the spark frequency increasing effect of fluvastatin without having a major effect on the amount of calcium released during individual sparks. In conclusion, we have found that fluvastatin, independently of the cholesterol level in the blood, consistently and specifically increased the frequency of calcium sparks in skeletal muscle cells, an effect which could be prevented by the addition of coenzyme Q10 to the diet. These results support theories favouring the role of calcium handling in the pathophysiology of statin-induced myopathy and provide a possible pathway for the protective effect of coenzyme Q10 in statin treated patients symptomatic of this condition.

Rosiglitazone Did Not Induce Acute Kidney Injury in Normocholesterolemic Rats Despite Reduction in Glomerular Filtration Rate

Background/Aims: Rosiglitazone (RGL) has been used to ameliorate lipids homeostasis and also to treat inflammatory diseases. However, RGL may reduce renal blood flow and glomerular filtration rate (GFR) predisposing to acute kidney injury (AKI). We investigated whether the treatment with RGL induces AKI in normocholesterolemic (NC) and hypercholesterolemic (HC) rats. Methods: We measured GFR by inulin clearance technique and we quantified urinary neutrophil gelatinase-associated lipocalin (uNGAL) in all groups at baseline and during Ang II-stimulated vasoconstriction. Moreover, we evaluated the presence of renal damaged by histologic examination. Results: At baseline, NC and HC had normal and similar GFR. RGL treatment reduced GFR only in NC+RGL. Unexpectedly, HC+RGL showed high levels of uNGAL although GFR was at normal range. During Ang II-stimulated vasoconstriction, all groups showed reduction in GFR to the same range and we found high levels of uNGAL and high score of renal damage in HC and HC+RGL. Conclusion: RGL acts distinctly in normocholesterolemia and in hypercholesterolemia. Reduction in GFR provoked by RGL treatment did not allow the diagnosis of AKI in NC even in the presence of ANG II-stimulated vasoconstriction. However, AKI was diagnosed in HC+RGL at baseline although GFR was within normal range.

The oleic acid esterification of policosanol increases its bioavailability and hypocholesterolemic action in rats

Policosanol comprises a mixture of long-chain aliphatic alcohols from sugarcane wax. More than 50 studies indicate that policosanol decreases serum cholesterol, while others failed to reproduce this effect. The objective of this investigation was to assess the bioavailability of esterified policosanol and non-esterified policosanol (NEP), in relation to their hypocholesterolemic effects. Sprague Dawley rats were given a daily oral dose of 100 mg/kg of NEP, 117 mg kg–1 of butyric acid esterified policosanol (BAEP), or 164 mg kg–1 of oleic acid esterified policosanol (OAEP). Policosanol absorption was evaluated in plasma between 0 and 3 hours after ingestion. To assess changes in total cholesterol, LDL-cholesterol, HDLcholesterol and triacylglycerols in plasma and liver 3-hydroxy- 3-methylglutaryl coenzyme A reductase (HMG- CoA red) phosphorylation, the rats were supplemented with nonesterified or esterified policosanol for 5 weeks. The results indicate that policosanol absorption was significantly greater in OAEP-treated rats than in those subjected to NEP or BAEP administration. OAEP significantly reduced plasma total and LDL-cholesterol in rats, in addition to a 5.6-fold increase (P < 0.05) in the hepatic content of phosphorylated HMG-CoA red over the control values. In conclusion, esterification of policosanol with oleic acid enhances policosanol bioavailability, and significantly improves the serum lipid profile in normocholesterolemic rats in association with the inactivation of HMG-CoA red controlling cholesterogenesis.

Concomitant administration of simvastatin with ivabradine in contrast to metoprolol intensifies slowing of heart rate in normo- and hypercholesterolemic rats.

Introductionβ-Blockers play a significant role in therapeutic heart rate (HR) management and angina control. In patients who are unable to tolerate β-blockers ivabradine could be particularly useful. The aim of the study was to establish whether concomitant administration of simvastatin with ivabradine or metoprolol had any effect on rat HR and blood pressure (BP).Material and methodsThe experiments were performed in hyper- and normocholesterolemic outbred Wistar rats. Animals were divided into 2 groups: receiving during 4 weeks normal diet (normocholesterolemic rats) or diet with 5% cholesterol and 2.5% cholic acid (hypercholesterolemic rats). Then rats received placebo (0.1% methylcellulose), 2) metoprolol 30 mg/kg bw; 3) ivabradine 10 mg/kg bw; 4) simvastatin 10 mg/kg bw; 5) simvastatin 10 mg/kg bw + metoprolol 30 mg/kg bw; 6) simvastatin 10 mg/kg bw + ivabradine 10 mg/kg bw. Drugs were given during a 4-week period. HR and BP measure were provided by an Isotec pressure transducer connected to a direct current bridge amplifier. For the further lipid profile examination, 0.25 ml of blood samples were taken.ResultsAfter administration of ivabradine with simvastatin to normocholesterolemic and hypercholesterolemic rats the mean HR was significantly reduced as compared to rats receiving simvastatin (312.0 ±30.2 min−1 vs. 430.7 ±27.8 min−1, p<0.05); (329.8 ±24.2 min−1 vs. 420.5 ±9.2 min−1, p<0.05) or ivabradine alone (312.0 ±30.2 min−1 vs. 350.2 ±16.0 min−1, p<0.05); (329.8 ±24.2 min−1 vs. 363.0 ±21.7 min−1, p<0.05).ConclusionsConcomitant administration of simvastatin with ivabradine intensified slowing of HR, although it did not influence BP in normo-and hypercholesterolemic rats. Statin-induced intensification of HR deceleration after metoprolol administration was not observed.

The importance of atrial fibrillation/flutter as a cause of ischemic stroke

Int J Cardiol 2010;144:1–2. [9] Aronow HD, Topol EJ, Roe MT, et al. Effect of lipid-lowering therapy on early mortality after acute coronary syndromes: an observational study. Lancet 2001;357:1063–8. [10] Newby LK, Kristinsson A, Bhapkar MV, et al. Early statin initiation and outcomes in patients with acute coronary syndromes. JAMA 2002;287:3087–95. [11] Spencer FA, Allegrone J, Goldberg RJ, et al. Association of statin therapy with outcomes of acute coronary syndromes: the GRACE study. Ann Intern Med 2004;140:857–66. [12] Stenestrand U, Wallentin L. Early statin treatment following acute myocardial infarction and 1-year survival. JAMA 2001;285:430–6. [13] Fonarow GC, Wright RS, Spencer FA, et al. Effect of statin use within the first 24 hours of admission for acute myocardial infarction on early morbidity and mortality. Am J Cardiol 2005;96:611–6. [14] Pan W, Pintar T, Anton J, Lee VV, Vaughn WK, Collard CD. Statins are associated with a reduced incidence of perioperative mortality after coronary artery bypass graft surgery. Circulation 2004;110:II45–9. [15] DiNapoli P, AntonioTaccardi A, Grilli A, Spina R, FelacoM,Barsotti A, et al. Simvastatin reduces reperfusion injurybymodulatingnitric oxide synthaseexpression: anexvivo study in isolated working rat hearts. Cardiovasc Res 2001;51:283–93. [16] Lefer AM, Campbell B, Shin YK, Scalia R, Hayward R, Lefer DJ. Simvastatin preserves the ischemic-reperfused myocardium in normocholesterolemic rat hearts. Circulation 1999;100:178–84. [17] Cannon CP, Braunwald E, McCabe CH, et al. Intensive versus moderate lipid lowering with statins after acute coronary syndromes. N Engl J Med 2004;350:1495–504. [18] Leeper NJ, Ardehali R, deGoma EM, Heidenreich PA. Statin use in patients with extremely low low-density lipoprotein levels is associated with improved survival. Circulation 2007;116:613–8.

Hypercholesterolemia Abrogates Sevoflurane-Induced Delayed Preconditioning Against Myocardial Infarct in Rats by Alteration of Nitric Oxide Synthase Signaling

The aim of the current study was to determine whether hypercholesterolemia affects the delayed sevoflurane preconditioning against myocardial ischemia-reperfusion (IR) injury and, if so, the underlying mechanism. Male Sprague-Dawley rats fed 2% cholesterol-enriched chow for 8 weeks were subjected to sevoflurane preconditioning (2.4% vol/vol, 1 h) 24 h before myocardial ischemia was induced by occluding the left anterior descending coronary artery for 30 min followed by reperfusion for 120 min. The hemodynamic parameters left ventricular developed pressure, left ventricular end-diastolic pressure, and maximal rise/fall rate of left ventricular pressure were continuously monitored, and myocardial infarct size was determined at the end of reperfusion. The protein expression of myocardial nitric oxide synthase (NOS), Bcl-2, and Bad was assessed before ischemia. We found that the left ventricular hemodynamic parameters during the whole IR procedure and the myocardial infarct size did not significantly differ between the normocholesterolemic and hypercholesterolemic control groups. The hemodynamic parameters were all markedly improved during the reperfusion period, and the myocardial infarct size was significantly reduced by delayed sevoflurane preconditioning in normocholesterolemic rats, but all of these improvements were reversed by N-(3-(aminomethyl)benzyl) acetamidine (1400W, 1 mg/kg; i.v., 10 min before ischemia), a selective inducible NOS (iNOS) inhibitor, and 5-hydroxy decanoate sodium (5 mg/kg, i.v., 10 min before ischemia), a mitochondrial ATP-dependent K⁺ channel blocker. Such cardiac improvement induced by delayed sevoflurane preconditioning did not occur in hypercholesterolemic rats and was not exacerbated by 1400W or 5-hydroxy decanoate sodium. The expression of myocardial iNOS was markedly enhanced by delayed sevoflurane preconditioning in normocholesterolemic, but not in hypercholesterolemic rats. The expression of endothelial NOS and Bad did not differ among all groups. The expression of myocardial phosphorylated endothelial NOS, Bcl-2, and phosphorylated Bad in normocholesterolemic rats was not affected by delayed sevoflurane preconditioning but was decreased in the hypercholesterolemic control group, and this was not reversed by sevoflurane, compared with the normocholesterolemic control group. Taken together, these results indicate that sevoflurane preconditioning exerts delayed cardioprotection against IR injury in normocholesterolemic rats, which is blocked by hypercholesterolemia potentially via interference with the iNOS/mitochondrial ATP-dependent K⁺ channel pathway.

Hypolipidemic and Antiatherogenesis Effect of Culinary-Medicinal Pink Oyster Mushroom, Pleurotus salmoneostramineus L. Vass. (Higher Basidiomycetes), in Hypercholesterolemic Rats

The present study was conducted to investigate dietary supplementation of Pleurotus salmoneostramineus fruiting bodies on biochemical and histological effects in hyper- and normocholesterolemic rats. Six-week-old female Sprague-Dawley albino rats were divided into three groups of 10 rats each. Feeding of diet containing a 5% powder of the fruiting bodies of P. salmoneostramineus in hypercholesterolemic rats reduced plasma total cholesterol, triglyceride, low-density lipoprotein, total lipid, phospholipids, and LDL/HDL ratio by 22.55, 51.38, 69.23, 29.67, 16.61, and 65.31%, respectively. The mushroom also significantly reduced body weight in hypercholesterolemic rats. Moreover, it had no adverse effects on plasma albumin, total bilirubin, direct bilirubin, creatinine, blood urea nitrogen, uric acid, glucose, total protein, calcium, sodium, potassium, chloride, inorganic phosphate, magnesium, and enzyme profiles. Feeding mushroom increased total lipid and cholesterol excretion in feces. The plasma lipoprotein fraction, separated by agarose gel electrophoresis, indicated that P. salmoneostramineus significantly reduced plasma β and pre-β-lipoprotein, while it increased α-lipoprotein. A histological study of liver tissues by conventional hematoxylin-eosin and oil red O staining showed normal in mushroom feed hypercholesterolemic rat. This study suggests that the P. salmoneostramineus diet supplement provided health benefits by acting on the atherogenic lipid profile in hypercholesterolemic rats.

Concomitant Administration of Different Doses of Simvastatin with Ivabradine Influence on PAI-1 and Heart Rate in Normo- and Hypercholesterolaemic Rats

Ivabradine is a novel heart rate lowering agent that inhibits If ionic current in the sinus node and demonstrates antiischaemic and antianginal activity. The aim of the paper was to investigate the effect its dose-dependent drug-drug interaction with simvastatin inhibitor HMGCo-A has on PAI-1 blood level, heart rate and blood pressure. The experiments were performed in hyper- and normocholesterolemic Wistar rats receiving simvastatin (1 and 20 mg × kg−1 bw) with ivabradine (10 mg × kg−1 bw) during a 4-week period. Ivabradine exacerbated the decrease of PAI-1 in normocholesterolemic animals receiving simvastatin at a dose of 1 mg/kg bw and was not observed to have any significant influence on the PAI-1 values in rats receiving 20 mg × kg−1 bw simvastatin. Ivabradine, coadministered with simvastatin given at a dose of 20 mg × kg−1 bw, significantly slowed the heart rate in normocholesterolaemic and hypercholesterolaemic groups as compared to the group receiving ivabradine alone. Conclusion. The administration of ivabradine to normocholesterolaemic and hypercholesterolaemic rats receiving simvastatin significantly exacerbated the slowing of heart rate with no effect on blood pressure. The administration of ivabradine has been shown to demonstrate different effects on PAI-1 values depending on lipid disorders.

High Cholesterol Feeding May Induce Tubular Dysfunction Resulting in Hypomagnesemia

Background/Aims: Hypomagnesemia may induce hypercholesterolemia, but the contrary has not been described yet. Thus, magnesium homeostasis was evaluated in rats fed a cholesterol-enriched diet for 8 days. This study has a relevant clinical application if hypomagnesemia, due to hypercholesterolemia, is confirmed in patients with long-term hypercholesterolemia. Methods: Both hypercholesterolemic (HC) and normocholesterolemic rats (NC) were divided into sets of experiments to measure hemodynamic parameters, physiological data, maximum capacity to dilute urine (C_H_₂_O), variations (Δ) in [Ca²⁺]_i and the expression of transporter proteins. Results: HC developed hypomagnesemia and showed high magnesuria in the absence of hemodynamic abnormalities. However, the urinary sodium excretion and C_H_₂_O in HC was similar to NC. On the other hand, the responses to angiotensin II by measuring Δ [Ca²⁺]_i were higher in the thick ascending limb of Henle’s loop (TAL) of HC than NC. Moreover, high expression of the cotransporter NKCC2 was found in renal outer medulla fractions of HC. Taken together, the hypothesis of impairment in TAL was excluded. Actually, the expression of the epithelial Mg²⁺ channel in renal cortical membrane fractions was reduced in HC. Conclusion: Impairment in distal convoluted tubule induced by hypercholesterolemia explains high magnesuria and hypomagnesemia observed in HC.

Chemical sympathectomy induces arterial accumulation of native and oxidized LDL in hypercholesterolemic rats

The aim of the present study was to examine the effect of sympathectomy on plasmatic and arterial native and oxLDL levels, as well as arterial LDL receptors (LDLR) and scavenger receptors in hypercholesterolemic rats, which are normally protected against atherosclerosis.Neonatal Wistar rats received subcutaneous injections of either guanethidine for sympathectomy (Gua+HC) or vehicle (HC), then were fed 1% cholesterol for three months. Intact normocholesterolemic rats were used as control of the HC group. Total cholesterol (TC) and LDL-cholesterol were evaluated in the plasma and the abdominal aorta by an auto-analyzer. Plasmatic and aortic oxLDL and native LDL-apo B100 were assessed by a sandwich ELISA. Aortic and hepatic native LDLR and aortic scavenger receptors (CD36 and SR-A) were quantified at mRNA and protein levels by real time PCR and western immunoblot. The effect of hypercholesterolemia was limited to an increase in plasmatic TC and LDL-cholesterol and a decrease in aortic apoB100 and aortic and hepatic LDLR. Hypercholesterolemia and sympathectomy in combination increased markedly plasmatic and aortic TC, LDL-cholesterol, apo B100 and oxLDL together with aortic scavenger receptors, but reduced markedly aortic and hepatic LDLR.Sympathectomy broke down the rat's protection against hypercholesterolemia by promoting accumulation of native and oxLDL in the aorta via scavenger receptors.