Myocardial morphometric characteristics in swine.

Abstract

SUMMARYWe have quantified the ultrastructure of myocardial cells in tissue samples obtained from six adult normal Yucatan swine, tissue samples were obtained from 20 different sites in the left ventricle, right ventricle, and interventricular septum. The samples were processed for electron microscopy and quantitative morphometric analysis. The percent relative volumes of myoflbrils, mitochondria, transverse tubular system, sarcoplasmic reticulum, and clear intracellular space were determined using stereologic&l morphometric methods. Overall, the data were distributed homogenously among the 20 individual sites. However, when certain eubcellular components were examined regionally, some differences appeared. The mitochondrial:myofibril volume ratios were significantly increased in the left ventricle and interventricular septum compared to the right ventricle. They also were greater in the endocardial region compared to the epicardium, which is consistent with higher metabolic activity of these zones. Similarly, the sarcoplasmic reticulum :myofibril ratio was greater in the endocardial region vs. the epicardial region and the basal layer compared to the mid-layer, suggesting the greater need for provision of calcium ions in these particular cones. Since the swine is a convenient large animal fur physiological studies, these results indicate that swine can also be used for quantitative morphometric measurements of myocardial changes in normal and pathologic hearts, and for the study of regional changes in various layers and regions of heart walls. Circ Res 49: 434-441, 1981 MANY experimental models of cardiac hypertrophy have been used to describe the different functional, structural, and biochemical alterations that occur during the development of hypertrophy and failure in the heart. We nave used swine as a model of cardiac hypertrophy (White et al., 1979) since its response to exercise stress is similar to that in humans. Also, the swine has a coronary artery distribution similar to that of the normal human (Lumb and Hardy, 1963), a limited coronary collateral circulation (Blumgart et al., 1950), and a similar ratio of heart weight to body weight to that of man (Schaper, 1971). Therefore it is an appropriate model for comparison to man (Blumgart et al., 1950; Lumb andSingletary, 1961;1962;Lumb and Hardy, 1963;Kong et al., 1969). However quantitative ultrastructural studies of the normal and hypertrophic heart have been conducted mainly in smaller species, e.g., rats (Page et al., 1971;Anversa et al., 1976Anversa et al., , 1978Legato, 1976; Wendt-Gallitelli and Jacob, 1977;McCallister et al., 1979;Tomanek et al., 1979), rabbits (Anversa et al., 1971;Goldstein et al., 1974), hamsters (Colgan et al., 1978), cats (Sheridan et al., 1977), and ferrets (Breisch et aL, 1980). Although ultrastructural studies have been conducted on the hearts of dogs (Vitali-Mazza and Anversa, 1972;Winkler et al., 1977;McCallister et al., 1978;Legato, 1979), it was not known whether the percentages of cell volume of ultrastructural ...

Homogenous protein programming in the mammalian left and right ventricle free walls

“…These data are consistent with several morphology studies on the density of cardiac mitochondria in the rat (1), dog (16), sheep (24), cat (10), and pig (22 vol% LV and 21 vol% RV) (23), which show that the relative cytosolic volume of mitochondria are identical across species. The enzymatic activities of aconitase and Mn-SOD were the same in porcine RV and LV, when normalized by cardiomyocyte content, consistent with previous measures of metabolic enzyme activities between the ventricles (6,7,26).…”

Enhanced resistance to permeability transition in interfibrillar cardiac mitochondria in dogs: effects of aging and long-term aldosterone infusion

“…Direct comparisons of the LV and RV in healthy young male rats found a 20% greater mitochondrial volume density in the RV as assessed by electron microscopy, but no difference in mitochondrial respiratory capacity in permeablized cardiomyocyte bundles or in the activity of complexes I-IV or citrate synthase in myocardial homogenates (29). In contrast, mitochondrial volume density was not different between LV and RV myocardium in healthy young pigs (52). Here we show that mitochondrial yield and functional differences between SSM and IFM were qualitatively similar in the LV and RV with responses to aging and aldosterone infusion (Figs.…”

Regulation of Ion Gradients across Myocardial Ischemic Border Zones: A Biophysical Modelling Analysis

“…The surface to volume ratio of a cell is reported as m [37], [38] in rat and rabbit myocytes, corresponding to a value of mm. The relative SR volume was set to of intracellular volume, giving an value of , based on reported values of of cell volume [37], [39], [40] in mouse, rat and swine. The relative mitochondrial volume () was set to based on an estimated mitochondrial cell volume fraction of [37], [40].…”

“…The relative SR volume was set to of intracellular volume, giving an value of , based on reported values of of cell volume [37], [39], [40] in mouse, rat and swine. The relative mitochondrial volume () was set to based on an estimated mitochondrial cell volume fraction of [37], [40]. The cytosol volume fraction was set to of the intracellular space, resulting in an value of .…”