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At least 19 recordsLinked to original sources
PubMed1978

Comparison of anoxic changes in isolated rat cardiac myocytes in suspension and in histological sections.

Cardiac myocytes from adult rat were isolated by heart perfusion in the presence of collagenase and incubated in the absence and presence of oxygen. As a result of anoxia, there was a gradual increase in plasma membrane permeability, noted as an increase in succinate-stimulated oxygen uptake, a decrease in trypan blue exclusion frequency, a leakage of cytosolic lactate dehydrogenase activity and an increased proportion of swollen, irregularly contracting myocytes. The contractions of the damaged myocytes resembled the known non-physiologic contractions of the heart, i.e. extrasystoles, arrhythmia, fibrillation or block. After different periods of time of anoxia myocyte pellets were fixed in formalin, sectioned and examined by light microscopy. The appearances of the myocytes in suspension were compared with those in paraffin-embedded sections. Special attention was given to the hematoxylin basic fuchsin picric acid stain and it was noted that the basic fuchsin was taken up by contracted or damaged myocytes, which according to their morphology in suspension revealed irregular contractions, but not by undamaged or necrotic myocytes.

Animals↗
PubMed1978

Absolute morphometric study of myocardial hypertrophy in experimental hypertension. II. Ultrastructure of myocytes and interstitium.

The left ventricular myocardium of normal and hypertensive rats has been characterized morphometrically in the endocardial and epicardial zones. Compared to the epicardial regions, the normal endocardial regions contain 30 per cent more myocytes, 27 per cent less interstitial space, 48 per cent less capillary volume, 17 per cent less capillary surface, and the same capillary length per unit tissue volume. In terms of both the relative and absolute volumes and surface areas of their organelles, the cytoplasmic composition of normal endocardial and epicardial myocytes is nearly identical. After 14 weeks of hypertension, induced by constriction of the left renal artery, left ventricular weight is increased by 30 per cent, wall thickness by 42 per cent. The number of myocytes and the total length of capillaries remain constant. The epicardial region enlarged 37 per cent with proportional increases of myocyte and interstitial volumes. In contrast, the endocardial enlargement was only 26 per cent, comprised of 21 per cent hypertrophy of myocytes and a 55 per cent increase in interstitial components. Expansion of capillary lumina accounted for much of the interstitial enlargement throughout the myocardium. Hypertrophy of myocytes is 76 per cent greater in the epicardial region and is accompanied by a reduced mitochondria to myofibril ratio and disproportionately large increases (2- to 3-fold) in both smooth endoplasmic reticulum and T-system volume and surface area. On a cellular basis the absolute morphometric characteristics of myocytes from hypertensive rats are significantly different from normal, and significant differences occur between the inner and outer layers of the myocardium for practically every cytoplasmic component.

Animals↗
PubMed1978

Absolute morphometric study of myocardial hypertrophy in experimental hypertension. I. Determination of myocyte size.

A method for determining the mean absolute volume of a specific population of cells within a tissue is described and applied to the measurement of endocardial and epicardial myocytes in the left ventricle of normal and hypertensive rats. The technique, based on nuclear counts per unit area in tissue slices of different known thicknesses, measures the mean cell volume per nucleus independent of previously unknown nuclear dimensions and systematic counting errors. Duplicate determinations, demonstrating reproducibility, were made in mutually perpendicular longitudinal and transverse sections of the myocardium. Combining these light microscopic measurements with electron microscopic data enabled the evaluation of the mean diameter and length of the cylindrical myocyte nuclei showing those in the epicardial cells to be significantly longer than the nuclei in endocardial cells. It was estimated that 2 to 4 per cent of ventricular myocytes are binucleate. After 1 to 4 weeks of hypertension, induced by constriction of the left renal artery, endocardial myocytes were enlarged 21 per cent, from 10,370 +/- 410 to 12,520 +/- 490 cu. micrometer., while epicardial myocytes showed a 37 per cent hypertrophy, from 12,600 +/- 1,600 to 17,300 +/- 1,100 cu. micrometer. The availability of a reliable determination of cell volume will make possible the interpretation of much biochemical, functional, and morphometric data at the whole cell level.

Animals↗
PubMed1979

Histological diagnosis of myocardial injury. Comparison of hematoxylin-basic fuchsin-picric acid (HBFP)-stained sections obtained during autopsy with isolated viable rat cardiac myocytes exposed to anoxia.

The light microscopic appearances in hematoxylin-basic fuchsin-picric acid (HBFP)-stained histological sections from cardiac and skeletal muscle tissue were put in relation to the reactions of isolated viable rat cardiac myocytes exposed to anoxia in suspension and their morphology in paraffin-embedded sections. Special attention was paid to prenecrotic phases of myocytic injury which were followed, in viable rat cardiac myocytes, by light microscopy, and confirmed with biochemical assays indicating increased plasma membrane permeability. In cases of sudden death, and traumatic injury to the heart and skeletal muscle, there was good agreement between alterations demonstrated with the HBFP technique and alterations of viable rat cardiac myocytes exposed to anoxia. In isolated myocytes, these alterations were associated with irregular contractility which, when occurring in situ, might have influenced the cardiac function prior to death. Moreover, the changes develop at a much faster rate than the inflammatory reaction following tissue injury and may therefore be regarded as an early vital phenomenon of significance in clinico-pathological and medico-legal considerations.

Adolescent↗
PubMed1979

Differences in regional capillary distribution and myocyte sizes in normal and hypertrophic rat hearts.

Data are reported which show significant regional capillary differences in left ventricular endocardium and epicardium of normal rats and of rats with hyperthyroid-induced cardiac hypertrophy. The epicardial region of control rats has 38% more capillaries than the endocardial region. Control endocardial myocytes are 62% larger in cross-sectional area than epicardial myocytes. Hypertrophic hearts exhibit regional differences in capillary density similar to those in the normal hearts, but there is an overall reduction of 12 and 17.5% in capillary density in both regions. The average cross-sectional area of myocytes increases 34.5% in the epicardium and 22.5% in the endocardium.

Animals↗
PubMed1978

Effect of dibutyryl cyclic AMP and analogs on the rate of contractions of myocytes in culture.

2O, 6N-butyryl, 3', 5'-cyclic monophosphate (dibu cAMP) when added to fetal rat heart cells in culture inhibits myocyte contraction. This inhibition is 100, 84 and 51% complete when the dibu cAMP concentration used is 2, 0.2 and 0.02 mM, respectively. The potency of dibu cAMP derivatives in myocyte contraction inhibition follows the order, dibu cAMP greater than 6N-bu cAMP greater than 2O-bu cAMP = AMP greater than butyrate. The inhibition caused by the first three chemicals is greater than 70%.

Animals↗
PubMed1977

Hexose monophosphate shunt in isolated cardiac myocytes from normal rats.

The activity of the hexose monophosphate shunt was studied in myocytes obtained from the ventricles of normal, adult, male rats. When myocytes were incubated in buffer containing either 1-14C- or 6-14C-labeled glucose the ratio of C-1/C-6 14CO2 evolved was essentially unity. The addition of plasma levels of amino acids did not alter this finding. If, however, a competitive substrate (pyruvate, octanoate, acetate, or lactate) was present, in sufficient quantity to lower the oxidation of glucose to approximately 20% of the control, the C-1/C-6 14CO2 ratio rose to values between 1.3 and 2.1. This ratio was dependent on the concentration of the competitive substrate, which was dependent on the buffer system. The data indicates that the hexose monophosphate shunt is active in the heart because it can be demonstrated when a substrate, which competes with glucose for oxidation, is present. The presence of competing substrates parallels the situation occuring in vivo.

Acetates↗
PubMedDate not supplied

Regional myocyte size in normotensive and spontaneously hypertensive rats.

Regional differences in cell size in the hearts of rats with and without cardiac hypertrophy were studied using isolated muscle cells. Isolated cardiac myocytes were prepared from left ventricular free wall inner and outer halves and the right ventricle of six male 12-week-old spontaneously hypertensive (SHR), Wistar-Kyoto (WKY) and Fischer-344 rats. In SHR, blood pressure was increased to 188 +/- 4 (SEM) mm Hg versus 143 +/- 2 and 133 +/- 10 for WKY and Fischer rats, respectively (p less than 0.001). Total heart weight was increased to 1103 +/- 29 mg in SHR compared to 824 +/- 21 in WKY and 951 +/- 23 in Fischer rats (p less than 0.001. Isolated cardiac myocytes were prepared by perfusion of isolated hearts with Ca++ free Hanks' solution containing EGTA followed by collagenase-containing media. Mean length, width and volume of 150 cells stained with hematoxylin and eosin from each site were measured with a sonic digitizer. Two nuclei were present in 85 to 87% of isolated cells from all strains and regions. There was no difference among strains in right ventricular cell length, width, or volume, nor between left ventricular inner and outer halves within each strain. Left ventricular cells were larger than right ventricular cells (p less than 0.05) in all strains. Left ventricular cells of SHR were larger than left ventricular cells of WKY of Fischer rats in proportion to the increase in total heart weight, indicating that cardiac enlargement in SHR is due to increased cell size rather than increased cell number.

Animals↗
PubMedDate not supplied

[Aortic myocytes and calciferol-induced arterial calcification: ultrastructural and biochemical study].

Thirty0seven rats were given Vitamin D2 orally at the daily dose of 4000 I.U. for two months, then 8000 I.U. for the following two months and 26 rats were used as controls. Batches of both intoxicated and control rats were sacrificed on the 15, 30, 45, 90 and 120 days after the onset of the experiment. This chronic calciferol intoxication allowed a better understanding of the calcifying process. Modified myocytes were observed early and for a long time in and around the mineralizing foci. They had the ultrastructural and histochemical characteristics of cells with an activated metabolism: excessive development of the organelles linked with synthesis processes, hyperactivity of phoshatases, of lysosomic enzymes and of enzymatic systems of cell respiration and glycolysis. Some data of the present study support the hypothesis that myocytes may be a local factor for the aortic calcification process: by increasing the conjonctive constituents calciphily, by producing phosphate and sulphate anions as well as calcifiable organic materials (glycoproteins, GAG), by modification in their own environmental physico-chemical conditions favorous to calcium precipitation (acidosis, phosphate and sulphate anions supersaturation).

Animals↗
PubMed1979

[Ultrastructural demonstration of rabbit heart myocyte metabolism during fasting].

Thirty mature rabbits were completely deprived of food but water ad libitum for 10 days, then half of the animals were decapitated. The remaining animals were sacrificed 10 days after a sound diet. Histological, histochemical (estimation of glycogen, lipids, acid glycosamineglicans) and electron microscopic investigation of the myocardium was carried out. Degenerative and necrobiotic alterations were not revealed in muscular cells of the heart. At fasting accumulation of lipids and glycogen in the cardiac myocytes was evident. In fasting animals ultrastructure of the muscular cells of the heart demonstrated a certain decrease in synthetic processes. After a 10-day sound diet, the cardiac myocytes were actively involved into the process of intracellular regeneration. Increased lipid content in the rabbit myocardium, occurring at fasting, is connected with the necessity to provide the heart with an effective energy substrate required to preserve its contractile function and in this way adaptive-compensatory processes are demonstrated.

Adaptation, Physiological↗
PubMed1979

[Effect of sodium hydroxybutyrate on the ultrastructure of cross-striated muscle tissue myocytes during physical exercise].

The ultrastructure of myocytes of the rat myocardium and skeletal muscles was studied in the control during physical exercise and under conditions of two-week sodium hydroxybutyrate pretreatment. It was shown that single maximum physical exercise caused significant changes in the fine structure of cardiomyocytes and somewhat less changes in a pronounced intermyofibrillar edema, the swelling of mitochondria and an acute fall of the glycogen level. A two-week sodium hydroxybutyrate pretreatment prevented the changes in the myocytes. The observed structure normalization induced by the drug is likely to be due to the specific nature of its metabolic transformation and to the effect on the energy exchange.

Animals↗
PubMed1979

Morphological and metabolic studies on adult cardiac myocytes.

We have previously described detailed procedures for isolating rat and canine myocytes from adult ventricular tissue, and have investigated ultrastructural and functional properties of these cells. The effects of isolation on cell morphology were tested by comparative scanning (SEM) and transmission electron microscopy (TEM) of adult canine cardiac myocytes. Cells cleanly separated at the lateral sarcolemmal borders and at the intercalated discs. Since the cells were contracted during fixation, SEM of the lateral cell borders showed longitudinal folds and transverse ridges. There were rows of regular protrusions corresponding to the mitochondria immediately beneath the sarcolemmal surface. Openings in the sarcolemmal membrane occurred at regular intervals at the level of the Z-bands and may represent the sites of externalization of the transverse tubular system. By SEM, the intercalated disc junction appeared as a microvillar border and this corresponded directly to the scalloped appearance seen by TEM. A controlled sonication procedure was developed to allow specific removal of the sarcolemma without disruption of underlying organelles. This allowed visualization of the cellular organization of myofibrils, mitochondria and the transverse tubular system. These cells retain biochemical and enzymatic characteristics of adult dog cardiac tissues such as ouabain and insulin sensitivity, fatty acid and lipoprotein uptake and metabolism, and prostaglandin synthesis. This cytological preparation permits the correlation of these types of metabolic studies with the known functions of isolated subcellular organelles of the myocardium.

Animals↗
PubMed1979

Electron probe microanalysis of elemental composition of mouse cardiac myocytes during post-natal maturation.

Elemental concentrations in the cytoplasm and nucleus of t tests post-natal mouse myocytes were measured at 2, 4, 8, 16, 32 days and in adults using electron probe X-ray microanalysis. Using an analysis of variance test, significant age dependent changes were found in intracellular potassium, sulfur, phosphorus, and chlorine concentrations (mg/kg dry weight), while sodium and magnesium concentrations did not show significant changes. The application of t tests following linear regression analyses (age versus concentration for each element) did, however, give a significant slope for cytoplasmic sodium, potassium, sulfur, and phosphorus values. The findings correspond closely with an emission spectroscopy-titrimetric study of whole heart ventricle of the same developmental period (Hazelwood and Nichols, '70).

Aging↗
PubMed1976

The absence of 2,3-diphosphoglycerate from myocytes, hepatocytes and adipocytes.

Myocytes, hepatocytes and adipocytes were prepared from heart, liver and epididymal fat pad of the rat. No detectable level of 2,3-diphosphoglycerate was found. Evidence is also presented which indicates the absence from these cells of 2,3-diphosphoglycerate mutase and 2,3-diphosphoglycerate phosphatase. Previous findings by others of the presence of 2,3-diphosphoglycerate and 2,3-diphosphoglycerate mutase probably resulted from erythrocytes sequestered in the tissue.

Adipose Tissue↗
PubMed1976

Chemical transmission between rat sympathetic neurons and cardiac myocytes developing in microcultures: evidence for cholinergic, adrenergic, and dual-function neurons.

Electrophysiological studies were made on microcultures (300-500 mum in diameter) in which solitary sympathetic principal neurons from newborn rats grew on previously dissociated rat heart cells. Some neurons inhibited,some excited, and others first inhibited and then excited the cardiac myocytes. Application of drugs provided evidence for secretion of acetylcholine by the first group, catecholamines by the second, and both acetylcholine and catecholamines by the third. Solitary neurons which inhibited themyocytes usually excited themselves at nicotinic synapses (autapses).

Acetylcholine↗
PubMed1979

[Morphologic aspects of cardiac myocyte differentiation in Black Sea--Sea of Azov sturgeon (Acipenser güldenstädti colchicus V. Marti)].

Processes of ultrastructural organization of cardiac myocytes have been studied in the Russian sturgeon (Acipenser güldenstädti colchicus V. Marti) during germinal, prelarval, larval periods of development and in mature specimens. One of the main peculiarities of early cardiogenesis in this representative of Chondrostei fishes is a prolonged, observed during germinal and early prelarval periods, repression in multiplication of myocardial cells. Decreasing amount and size of yolk platelets in cytoplasm of these cells at the end of the germinal period could be connected with their intensive specific differentiation and increasing functional activity. Accumulation of free lipids during this period and their decreasing contents in early prelarval period demonstrate a certain transition to another way of metabolism. The data obtained on ultrastructure in mature specimens corresponds mainly to modern ideas on organization of the cardiac muscular tissue in other species of lower vertebrates.

Animals↗