Václav Pelouch

Effect of melatonin, captopril, spironolactone and simvastatin on blood pressure and left ventricular remodelling in spontaneously hypertensive rats.

Objective Melatonin was shown to reduce blood pressure, oxidative load and to increase nitric oxide bioavailability predisposing melatonin to have antiremodelling potential. Design The aim of this study was to show whether melatonin can reverse left ventricular remodelling in spontaneously hypertensive rats (SHR) and to compare this potential protective effect with captopril, spironolactone, or simvastatin. Methods Six groups of 3-month old rats (eight per group) were treated for 5 weeks: control untreated Wistar rats, control SHR, SHR plus melatonin (10 mg/kg per 24 h), SHR plus captopril (100 mg/kg per 24 h), SHR plus spironolactone (200 mg/kg per 24 h) and SHR plus simvastatin (10 mg/kg per 24 h). Their systolic blood pressure (SBP) was measured by the tail-cuff method. The relative weights of the left ventricle, nitric oxide synthase (NOS) activity, endothelial NOS and nuclear factor kappa B (NF-κB) protein expression, conjugated dienes concentration, level of collagenous proteins and hydroxyproline were measured. Results SBP was reduced by all drugs investigated but most prominently by captopril in SHR. The activity of NOS and endothelial NOS expression increased in the left ventricles of SHR compared with controls. Melatonin and spironolactone further increased NOS expression. Left ventricular oxidative load, estimated by NF-κB expression and conjugated dienes concentration, increased in SHR. Only melatonin reduced NF-κB expression and decreased conjugated diens concentration. Only captopril reduced left ventricular hypertrophy in SHR, whereas melatonin reduced collagenous protein concentration and hydroxyproline content in the left ventricle. Conclusion It is concluded that although melatonin, in comparison with captopril, did not reverse left ventricle hypertrophy, it reversed left ventricular fibrosis. This protection by melatonin may be caused by its prominent antioxidative effect.

Continuous light and L-NAME-induced left ventricular remodelling: different protection with melatonin and captopril.

Objective Blood pressure enhancement induced by continuous light exposure represents an attractive but rarely investigated model of experimental hypertension. Design and methods The aim of this study was to show whether the combination of continuous light (24 h/day) exposure and chronic NG-nitro-L-arginine-methyl ester (L-NAME) treatment induces remodelling of the left ventricle and whether captopril or melatonin can modify these potential alterations. Six groups of 3-month-old Wistar rats (nine per group) were treated for 6 weeks: control (untreated), L-NAME (40 mg/kg per day), exposed to continuous light, L-NAME treated and exposed to continuous light (L24), L24 rats treated with either captopril 100 mg/kg per day, or melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP), relative weights of the left ventricle, endothelial nitric oxide synthase (eNOS) and angiotensin-converting enzyme (ACE) expression in tissues, malondialdehyde and advanced oxidation protein product concentrations in the plasma and hydroxyproline levels in collagenous protein fractions were measured. Results The continuous light and L-NAME treatment led to hypertension, left ventricular hypertrophy (LVH) and fibrosis. An increase in SBP was completely prevented by captopril and partly by melatonin in the L24 group. Both drugs reduced oxidative damage and attenuated enhanced expression of ACE in the myocardium. Neither of the drugs prevented the attenuation of eNOS expression in the combined hypertensive model. Only captopril reduced LVH development in L24, whereas captopril and melatonin reduced left ventricular hydroxyproline concentrations in soluble and insoluble collagen, respectively. The total hydroxyproline concentration was reduced only by melatonin. Conclusion In hypertension induced by a combination of continuous light and L-NAME treatment, melatonin and captopril protect the heart against pathological left ventricular remodelling differently.

Melatonin prevents fibrosis but not hypertrophy development in the left ventricle of NG-nitro-L-arginine-methyl ester hypertensive rats

Objective Melatonin was shown to reduce blood pressure, enhance nitric oxide availability and scavenge free radicals. There is, however, a shortage of data with respect to the effect of melatonin on pathological left ventricular remodelling associated with haemodynamic overload. Design We investigated whether melatonin was able to prevent left ventricular hypertrophy (LVH) and fibrosis associated with NG-nitro-L-arginine-methyl ester (L-NAME)-induced hypertension. Methods Four groups of male Wistar rats were investigated: control, L-NAME (50 mg/kg per day), melatonin (10 mg/kg per day) and L-NAME plus melatonin. Blood pressure was measured non-invasively each week. After 5 weeks of treatment the animals were killed and nitric oxide synthase (NOS) activity, endothelial and inducible NOS expression, the level of collagenous proteins, hydroxyproline and conjugated dienes in the left ventricle were determined. Results The administration of L-NAME inhibited NOS activity, increased conjugated dienes concentration, elevated blood pressure and induced LVH and fibrosis (indicated by increased collagenous proteins and hydroxyproline levels). The addition of melatonin to L-NAME treatment failed to prevent the attenuation of NOS activity and the development of LVH and prevented hypertension only partly. The administration of melatonin, however, completely prevented the increase in conjugated dienes concentration and the development of left ventricular fibrosis. NOS expression was not different among experimental groups. Conclusion Melatonin prevented the development of left ventricular fibrosis and the increase in oxidative load in rats with L-NAME-induced hypertension. The antifibrotic effect of melatonin seems to be independent of its effects on NOS activity and might be linked to its antioxidant properties.

Regression of left ventricular hypertrophy and aortic remodelling in NO‐deficient hypertensive rats: effect of l‐arginine and spironolactone

Aim:  We investigated, whether the substrate for nitric oxide (NO) formation –l‐arginine – and the aldosterone receptor antagonist – spironolactone – are able to reverse alterations of the left ventricle (LV) and aorta in Nω‐nitro‐l‐arginine methyl ester (l‐NAME)‐induced hypertension.

Effect of hypo- and hyperthyroid states on phospholipid composition in developing rat heart.

The aim of this study was to examine the effect of hypo- and hyperthyroidism on the phospholipid composition in developing rat heart. The hypothyroid state (PTU) was induced by 0.05% 6-n-propyl-2-thiouracil in drinking water given to nursing mothers from the postnatal day 2–21. The hyperthyroidism (T3) was made by daily injection of 3,3′,5-triiodo-L-thyronine (10 μg/100 g body wt) to newborns in the same time period. Age matched intact littermates were taken as euthyroid controls. PTU decreased the concentration of total phospholipids (PL), choline phosphoglycerides (PC), ethanolamine phosphoglycerides (PE) and diphosphatidylglycerol (DPG) and increased the proportion of plasmalogen component of PE (PLPE). T3 increased the concentration of PL, PC, PE, DPG and decreased PLPE in comparison with euthyroid controls. The ratio of saturated/unsaturated fatty acids (FA) in PE was decreased in PTU and increased in T3 group. The ratio of n-6/n-3 polyunsaturated FA in PC, PE and phosphatidylinositol (PI) was increased in PTU due to increase of 18:2n-6 and decrease of 22:6n-3 proportion. T3 decreased this ratio because of decline in 20:4n-6 and rise in 22:6n-3 proportion. Both hypo- and hyperthyroidism decreased the ratio of 20:4n-6/18:2n-6 in the majority of phospholipids. PTU decreased the unsaturation index in PC, PI and phosphatidylserine. It is concluded that thyroid state plays an essential role in the development of membrane phospholipid components in cardiac membranes during the early postnatal period.

Effects of captopril, spironolactone, and simvastatin on the cardiovascular system of non-diseased Wistar rats

a Department of Pathophysiology, School of Medicine, Comenius University, Bratislava, Slovak Republic b 3rd Clinic of Internal Medicine, School of Medicine, Comenius University, Bratislava, Slovak Republic c Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic d Center of Excellence NOREG, Slovak Republic e Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Slovak Republic f Department of Medical Biochemistry, 2nd School of Medicine, Charles University, Prague, Czech Republic g Department of Physiology, School of Medicine, Charles University, Hradec Kralove, Czech Republic

A QUANTITATIVE EVALUATION OF REDOX-ACTIVE COMPOUNDS IN HUMAN BLOOD LIPIDS

Endogenous low molecular weight redox active compounds (RACs) comprise antioxidants, pro-oxidants, transition metal cations and metal chelators. Traditional electrochemical methods of measuring RACs are limited to aqueous solutions, thus providing information of only hydrophilic RAC pools. In a large number of diseases associated with oxidative stress and/or with metal toxicity, redox states of hydrophilic as well as hydrophobic compartments are modified, and therefore development of methods for their detection is both necessary and important. The pools of lipid soluble RACs in reduced and oxidized forms in n-hexane extracts obtained from blood plasma, erythrocytes and whole blood of healthy donors were determined by spectrophotometric detection of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, which stoichiometrically interacts with hydrogen donors in non polar solutions. Measurements of RACs in extracts before and after treatment with NaBH4 provided information about the levels of both reduced and oxidized RACs. Vitamin E was also determined using a fluorescence method. The results have shown that vitamin E is the major RAC in blood plasma lipids but not in blood cell lipids, where other phenols and quinones appear to predominate.

CONTINUOUS LIGHT EXPOSURE- AND L-NAME-INDUCED LEFT VENTRICULAR REMODELLING: INTERACTIONS WITH MELATONIN AND CAPTOPRIL: PP.29.155

Objective: Blood pressure enhancement induced by continuous light exposure represents an attractive but rarely investigated model of experimental hypertension. Design and Method: The aim of our study was to show whether the combination of continuous light (24 h/day) exposure and chronic L-NAME treatment induces remodelling of the left ventricle and whether captopril or melatonin are able to modify these potential alterations. Six groups (n = 8/group) of 3-month old Wistar rats were treated for six weeks: control (untreated rats) (c), L-NAME-treated (40 mg/kg/day) (L), exposed to continuous light (24), L-NAME treated and exposed to continous light (L24), light-exposed-L-NAME rats which were treated with either captopril 100 mg/kg/day (L24C), or melatonin (10 mg/kg/24 h) (L24CM). Systolic blood pressure (SBP) was measured by tail-cuff method. Relative weight of the LV, endothelial nitric oxide synthase (eNOS) and angiotensin converting enzyme (ACE) expression in tissues, malondialdehyd (MD) concentration in plasma, and the level of hydroxyproline in collagenous protein fractions were measured. Results: SBP increase was prevented by both drugs investigated but more prominently by captopril in L24. Expression of eNOS was decreased in the aorta of L24 compared to controls and neither drug has improved it. Expression of ACE was increased in L24 and both drugs prevented this increase. Increased oxidative load, estimated by concentration of MD in plasma, was reduced by both drugs. Only captopril reduced LV hypertrophy in L24, while both captopril and melatonin reduced hydroxyproline concentration(captopril in soluble collagenous fraction and melatonin in insoluble collagenous fraction) of the LV. Conclusion: It is concluded that although melatonin - in comparison to captopril - did not prevented the increase of LV weight, both captopril and melatonin prevented LV fibrosis development. This protective effect of both drugs may be due to their antioxidative effect and by reducing the ACE expression.

PROTEIN REMODELING OF THE HEART VENTRICLES IN HEREDITARY HYPERTRIGLYCERIDEMIC RAT: EFFECT OF ACE-INHIBITION

The aim of this study was to determine whether protein remodeling of the heart ventricles and remodeling of the aorta were present in hereditary hypertriglyceridemic (hHTG) rats and whether treatment with the angiotensin-converting enzyme inhibitor, captopril could prevent these alterations. Three groups of rats were investigated in a four week experiment control Wistar /C/rats, hHTg rats, hHTg rats given captopril (100 mg/kg/day) (hHTg + CAP). In the hHTg group, the increased systolic blood pressure (SBP) was associated with hypertrophy of the LV and RV. Protein profile analysis revealed an enhancement of metabolic protein concentration in both ventricles. The concentration of total collagenous proteins was not changed in either ventricles. However, alterations in composition of cardiac collagen were detected, characterized by higher concentration of hydroxyproline in pepsin-insoluble fraction and lower concentration of hydroxyproline in pepsin soluble faction in the LV. Hypertrophy of aorta, associated with the reduction of nitric oxide dependent relaxation, was also present in hHTG rats. Captopril normalized SBP, reduced left ventricular hypertrophy (LVH), diminished metabolic protein concentration in both ventricles, and improved NO-dependent relaxation of the aorta. Furthermore, captopril partially reversed alterations in hydroxyproline concentration in soluble and insoluble collagenous fractions of the LV. We conclude that hypertrophy of both ventricles and the aorta are present in hHTG rats, along with protein remodeling of both ventricles. Captopril partially prevented left ventricular hypertrophy development and protein remodeling of the myocardium.

Protein and Phospholipids Composition of Human Myocardium in Children with Congenital Heart Disease

Congenital heart disease is caused by abnormalities in the first 6–8 weeks of fetal life; incidence of heart malformations is approximately eight out of 1000; they resulted from aberrant organogenesis due to dysfunction of genes and the encoded proteins. We, therefore, analyzed protein and phospholipids profiles of human myocardium (tissue samples were obtained during surgery of children with normoxemic and hypoxemic congenital heart disease). Protein profile of the atrial and ventricular myocardium differs significantly; higher concentration of non-collagenous proteins due to contractile ones and lower concentration of extracellular matrix proteins (ECM) due to pepsin-insoluble collagenous proteins were in ventricles. Furthermore, there were significant differences in activities of metabolic enzymes from both glycolytic and oxidative pathways; it correlated with higher amount of cardiolipin in ventricle (mitochondrial phospholipids). Moreover, electrophoretic pattern of both heavy and light chains of myosin in ventricular and atrial musculature of damage myocardium were different; however, hypoxemia decreased ATPase activity of myosin in ventricle only. Compartmentation of troponin T between myofibrillar and cytosolic pools was not affected by hypoxemia. Synthesis of newly formed collagenous proteins depend on balance between synthetic and degradation processes; they are mediated by metaloproteinases (major band in atria and ventricle has mol..weight of 95kDa). Hypoxemia induced in atria both higher amount of collagen (predominantly collagen III) and activation of metaloproteinases. Significantly higher concentration of phospholipids was in ventricles; hypoxemia did not affected this atrio/ventricular difference. However, composition of phospholipids species in both parts of diseased myocardium did not differ (phosphatidylcholine and phosphatidylethanolamine occupied about 70% from all phosholipids). Surgeons, who are reconstructing cardiac anatomy, should be aware that they are dealing with biochemical abnormal tissue and they should respect atrio/ventricular differences.