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Biomedical subjects

V Pelouch

Publications and source records attributed to V Pelouch.

At least 37 records · Page 2Linked to original sources
PubMed1995

Molecular aspects of regulation of cardiac contraction.

Contractility of the myocardium is determined by the interaction of contractile (actin and myosin) and regulatory (troponin and tropomyosin) proteins in the presence of calcium ions and chemical energy. The formation of the actomyosin complex is affected by the modulatory (C-, F-, M-proteins, actinins) and interstitial proteins (different types of collagens, glycoproteins, glycosaminoglycans, elastins). Cardiac hypoxia is accompanied by qualitative and quantitative changes in both collagenous (change in the proportion of different extracellular matrix proteins) and non-collagenous proteins (formation of different isomyosins and isoforms of actins or regulatory proteins). This remodelling of cardiac musculature influences significantly the process of contraction and relaxation in the hypoxic myocardium.

Animals↗
PubMed1995

Protein profiling of the myocardium exposed to pressure overload from birth.

Aortic banding induced in 2-day-old (A2) and 6-day-old (A6) male rats increased the left ventricular (LV) weight after 60 days; right ventricular (RV) enlargement occurred in the A2 group only. The concentration of collagenous proteins in the LV was elevated in both experimental groups (more in the A2 rats) at the expenses of sarcoplasmic proteins. Aortic banding also affected the proportion of collagen types (lower collagen I, higher collagen III, V) and myosin light chains (higher LC1/LC2) in the LV. Similar changes of proteins in the RV were less pronounced.

Animals↗
PubMed1993

Role of extracellular matrix proteins in heart function.

The cardiac interstitium is populated by nonmyocyte cell types including transcriptionally active cardiac fibroblasts and endothelial cells. Since these cells are the source of many components of the cardiac extracellular matrix, and because changes in cardiac extracellular matrix are suspected of contributing to the genesis of cardiovascular complications in disease states such as diabetes, hypertension, cardiac hypertrophy and congestive heart failure, interest in the mechanisms of activation of fibroblasts and endothelial cells has led to progress in understanding these processes. Recent work provides evidence for the role of the renin-angiotensin-aldosterone system in the pathogenesis of abnormal deposition of extracellular matrix in the cardiac interstitium during the development of inappropriate cardiac hypertrophy and failure. The cardiac extracellular matrix is also known to change in response to altered cardiac performance associated with post-natal aging, and in response to environmental stimuli including intermittent hypoxia and abnormal nutrition. It is becoming clear that the extracellular matrix mainly consists of molecules of collagen types I and III; they form fibrils and provide most of the connective material for typing together myocytes and other structures in the myocardium and thus is involved in the transmission of developed mechanical force. The data available in the literature support the view that the extracellular matrix is a dynamic entity and alterations in this structure result in the development of heart dysfunction.

Cardiomegaly↗
PubMed1993

Alteration of collagenous protein profile in congestive heart failure secondary to myocardial infarction.

The rat model of myocardial infarction is characterized by progressive cardiac hypertrophy and failure. Rats with infarcts greater than 30% of the left ventricle exhibited early and moderate stages of heart failure 4 and 8 weeks after the occlusion of the left coronary artery, respectively. As heart failure is usually associated with remodeling of the extracellular matrix, a histological and biochemical study of cardiac collagenous proteins was carried out using failing hearts. Total collagen content in the right ventricle increased at 2, 4, and 8 weeks following occlusion of the left coronary artery whereas such a change in viable left ventricle was seen after 4 and 8 weeks. Total cardiac hydroxyproline concentration was increased in both right and left ventricular samples from the infarcted animals when compared to those of control; this increase was due to elevation of pepsin-insoluble collagen fraction. The myocardial noncollagenous/collagenous protein ratio was decreased in experimental right and left ventricular samples when compared to control samples. These findings suggest that an increase in cross-linking of cardiac collagen as well as disparate synthesis of collagenous and noncollagenous proteins occurs in this model of congestive heart failure.

Animals↗
PubMed1993

[The role of the myocardial interstitium in left ventricular remodeling after acute myocardial infarction].

An acute myocardial infarction (MI) is characterized by a change in the protein composition not only in the infarct area but, also, in the area not involved; the remodelling of cardiac tissue is the consequence of synthesis of qualitatively and quantitatively different collagenous and non-collagenous proteins. The authors discuss the biochemical and structural characteristics of extracellular space proteins (the main types of cardiac collagen include collagens I, III, IV and V, with an important role played by glycoproteins). The mechanisms involved in the alteration of the architecture of a left ventricle affected by an MI include the changed ratios of these proteins along with an effect on the structure and enzymatic activity of contractile proteins and myocyte slippage; these factors largely affect not only myocardial function but, also, the patient's prognosis. Despite a number of published data (mainly on the effect of ACE inhibitors), it is evident that the issue of controlling the quality and scar formation following an MI requires further study by clinical and experimental cardiologists.

Collagen↗
PubMed1993

Protein profiling of human atrial and ventricular musculature: the effect of normoxaemia and hypoxaemia in congenital heart diseases.

Samples of myocardial tissue were obtained during surgical intervention from children operated for different types of congenital heart disease (tetralogy of Fallot, ventricular and atrial septal defect). Sarcoplasmic, contractile and collagenous proteins were isolated by stepwise extraction from the both right ventricular and atrial musculature. It has been found that: a) the concentration of contractile proteins is significantly higher in the ventricles, b) the concentration of collagenous proteins is significantly higher in the atrium, c) the concentration of sarcoplasmic proteins was not different, d) in children with chronic hypoxia the above atrio-ventricular differences persisted. Moreover, the proportion of the soluble collagenous fraction in the atria was significantly increased.

Adolescent↗
PubMed1992

Functional changes in the right and left ventricle during development of cardiac hypertrophy and after its regression.

OBJECTIVE: The aim was to determine left and right ventricular functional reserves and collagen concentration during the development of cardiac hypertrophy and after its regression. METHODS: Two experimental models of cardiac hypertrophy (chronic thyroxine or isoprenaline treatment of adult rats) were compared 24 h and five weeks after the agent was last given. Pressure changes in the left (right) ventricle before and after acute aortic (pulmonary artery) ligation were recorded in open chest anaesthetised animals. The difference in dP/dtmax after and before ligation was regarded as the functional reserve. The total collagen concentration was determined in both ventricles separately by means of hydroxyproline. RESULTS: Left and right ventricular weight increased by 20% and 30% respectively in the two models employed. In the thyroxine treated group, the functional reserve of the left ventricle rose very noticeably, whereas in the isoprenaline treated group it decreased. The right ventricular functional reserve did not differ from that in the controls in either of the two groups. The collagen concentration rose in the left ventricle in the isoprenaline group only. Five weeks after the last administration of the agent, cardiac mass and ventricular function did not differ from the control values in either of the models studied; the only exception was the incomplete regression of left ventricular hypertrophy and persistent structural and functional impairment of the left ventricle in the isoprenaline treated group. CONCLUSIONS: Our results indicate that hearts undergoing a comparable degree of experimental hypertrophy may have different functional and structural properties; significant differences were found between the right and left ventricular response. Regression of hypertrophy together with a reversal of ventricular function usually occurs unless the myocardium has received severe structural damage.

Animals↗
PubMed1992

Lack of proportionality between gene dosage and total muscle protein content in the rat heart.

Counting of isolated cardiomyocytes has demonstrated that their number was 16.8 +/- 0.6 10(6) in both ventricles of weanling rats (28 days after birth), growing in litters of four (fast-growing). In rats growing in litters of 16 (slow-growing), the myocyte number was 11.8 +/- 0.8 10(6). In the control group (8 sucklings per litter), there were 14.2 +/- 10(6) cardiomyocytes. The fast-growing rats had more octoploid cells than slow-growing ones. Considering ploidy and cell number, the total number of myocyte genomes in fast-growing animals was 45% higher than in slow-growing ones. The total content of contractile proteins in fast-growing weanling animals was higher by 28% while sarcoplasmic proteins were 8% higher. This lack of correspondence between the number of myocyte genomes and muscle protein content was even more pronounced at the age of 110 days. The results are compared with the cytophotometric data concerning the lack of correspondence between the total protein content in a myocyte and its DNA amount and chromosome number, i.e., total dosage of the myocyte genes.

Animals↗
PubMed1989

Comparison of cardiopulmonary response to intermittent high-altitude hypoxia in young and adult rats.

Haemodynamic and heart weight parameters were compared in male rats exposed to intermittent high-altitude (IHA) hypoxia (barochamber, 8 h/day, 5 days/week, total of 24 exposures stepwise up to 7,000 m) starting either from the 4th day or the 12th week of postnatal life. Systemic arterial pressure and heart rate increased in adult IHA acclimatized animals only. Marked chronic pulmonary hypertension and right ventricular enlargement were found in both age groups. Right ventricular weight increased linearly with a rise of pulmonary blood pressure in animals exposed to IHA from the 4th day of life (r = 0.72); no significant relation was found in adult rats (r = 0.16). The close correlation between both variables in young hypoxic rats may be due to the ability of the developing heart to respond to chronic hypoxia by both hypertrophy and hyperplasia of myocytes.

Adaptation, Physiological↗
PubMed1989

The effect of chronic hypoxia on the developing cardiopulmonary system.

The effect of chronic hypoxia (barochamber, 8 h per day, 5 days a week, stepwise up to 7000 m) on some cardiac functional and metabolic parameters was compared in rats acclimatized either from the 4th day or the 12th week of postnatal life. Pulmonary hypertension and right ventricular enlargement were found in both age group. Whereas in young hypoxic animals the weight of the right ventricle increased linearly with the right ventricular pressure, in adult high altitude exposed rats this relation could not be proved. High altitude induced significant increase of concentration of collagenous proteins: in adult animals increased collagen III only, in young also collagen I. The changes of the energy metabolism were similar in both age groups: activity of enzymes of the lactate metabolism and glucose phosphorylation increased; on the other hand, catabolism of fatty acids decreased. Chronic hypoxemia significantly influenced also the myocardial metabolism in children with congenital heart disease; the aerobic capacity was decreased both in the atrial and ventricular tissue; atrial changes were even more pronounced. The type of changes was, however, different from the rat heart.

Acclimatization↗
PubMed1989

Intermittent high altitude--induced changes in energy metabolism in the rat myocardium and their reversibility.

Selected enzyme activities of energy metabolism were studied in the myocardium of laboratory rats exposed to intermittent altitude hypoxia (IAH, 4-8 h daily, 5 days a week, in a hypobaric chamber, stepwise up to 7,000 m). No significant differences were found between the right and the left ventricle in the control animals. Glucose-utilizing capacity (HK) and capacity for the synthesis and degradation of lactate (LDH) increased significantly in both ventricles during acclimatization. The other enzyme activities associated with anaerobic glycolysis (TPDH, GPDH) and those linked up in aerobic metabolism (MDH, CS) did not change significantly. On the other hand, the ability to break down fatty acids (HOADH) decreased significantly. All the above changes in the enzyme profile were found after only 24 4-h exposures, in both the hypertrophic right ventricle and the unenlarged left ventricle. When the length of daily exposure was raised from 4 to 8 h, the above changes were not intensified and 45 days after the last exposure to IAH, none of the given activity values differed from those estimated in the corresponding control animals.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

Free radical membrane scavengers in myocardium of rats of different age exposed to chronic hypoxia.

Age-dependent changes in myocardial content of vitamin E and total hydrophobic free radical scavengers were estimated in rats of different age. Comparatively high values of vitamin E (0.10-0.12 mg/g fresh tissue) were found in 2-day-old rats. The content of vitamin E was lower in 15- and 60-day-old and 40% higher in 120-day-old rats as compared with new-born animals. Total scavengers were monotonously falling down with age. Vitamin E contribution to total scavengers activity gradually increased in postnatal developmental period of cardiac muscle (from 10% for 2-day-old rats to 50% for 120-day-old rats). Chronic hypoxia (intermittent high altitude hypoxia - 7000 m) had no effect on the levels of cardiac total scavengers and vitamin E when the animals were acclimatized from the 5th postnatal day. Acclimatization of adult animals induced a drop in concentration of vitamin E and did not affect the level of total scavengers.

Aging↗
PubMed1988

The effect of isoprenaline on the phospholipid content of the compact and spongious musculature of the carp ventricular myocardium.

1. After a single injection of 40 mg kg-1 of isoprenaline to the carp, lysophospholipids appear in the tissue of the heart ventricle, ethanolamine plasmalogens increase and choline plasmalogens decrease; phosphatidylinositol is lowered in the spongious layer only. 2. Daily administration of 5 mg kg-1 of the drug leads, after 5 doses, to a dramatic decrease of the diphosphatidylglycerol content; during the subsequent 5 and 10 doses a return to normal values occurs. Shifts in plasmalogens are similar to those found after a single high dose. Some other phospholipids change significantly. 3. All changes reveal that the spongious musculature is more sensitive to the drug than the compact one.

Animals↗
PubMed1988

Age-dependent influence of a moderate altitude (1,350 m) on the rat cardiopulmonary system.

The aim of the study was to determine whether a moderate altitude (1,350 m, Strbské Pleso, High Tatras) would act as a hypoxic stimulus on the cardiopulmonary system of young and adult rats. We used three experimental groups of animals differing in the duration of time for which they were kept at the given altitude (60 and 120 days) and the age at which they were acclimatized (from the 5th and the 60th day of life). The controls were kept at an altitude of 200 m (Prague). We found that an altitude of 1,350 m produced a significant increase in blood pressure in the lesser circulation; this response did not depend on the animals' age. Right ventricular enlargement occurred at the same time and was more pronounced in rats which had been acclimatized from infancy. The systemic blood pressure fell mildly, but significantly, only in animals exposed to altitude from adulthood; elevation of the haematocrit was likewise recorded only in this group. The results show that even a moderate altitude influences the cardiopulmonary system of the rat in a manner characteristic of the effect of chronic hypoxic hypoxia.

Acclimatization↗