Proliferation und Regeneration am Myokard

Klinge, O

doi:10.1007/bf00330719

Cited by 50 publications

(1 citation statement)

References 64 publications

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“…Subsequently, some support for this concept was derived from experiments showing limited mitotic activity which persisted after birth but which practically ceased to exist by the fourth postnatal week. 23 " 24 Our present experiments indicate that the rate of cardiac cellular proliferation may be influenced by the rate of growth of the whole heart and may be relatively independent of age during the early postnatal period. It appears that the total number of myocytes in the heart does not seem to be programmed to a constant number, related only to age, but may also be affected by the growth of the rat during the postnatal period.…”

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The influence of aging and growth on the postnatal development of cardiac muscle in rats.

Rakusan

Raman²,

Layberry

et al. 1978

Circulation Research

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SUMMARY We studied the effects of different rates of postnatal body growth on the growth of rat myocytes. Growth rates were altered by adjusting the number of newborn animals per litter to 4 (fast-growing), 8 (normal), or 16 (slow-growing). On the 21st postnatal day, average left ventricular weights (mg ± SEM) were 80 ± 5 in slowgrowing 131 ± 8 in normal, and 183 ± 5 in fast-growing rats. Average myocyte diameters, obtained from direct microscopic measurements in longitudinal sections prepared from eight animals in each group, were 8.6 ± 0.3, 9.8 ± 0.2, and 10.2 ± 0.3 fim, respectively. The total number and total length of myocytes constituting the left ventricle were estimated, assuming a constant length-to-width ratio and cyclindrical model of myocytes. The estimated total number of myocytes constituting the respective left ventricles were 23.6 ± 2.0, 24.5 ± 2.2, and 31.1 ± 2.1 millions. All differences between experimental groups were significant by analysis of variance. When the estimated total numbers of myocytes and their estimated total lengths were related to the left ventricular weights, a significant linear correlation was obtained, which indicated their dependence on the organ growth and their relative independence of age. These indications were strengthened further by analysis of covariance, which showed that the differences in all morphometric data among the three groups of hearts may be explained entirely by different growth rates of the left ventricle. These results also suggest that the accelerated growth of the heart during the early postnatal period is associated with increased proliferation of myocytes.PROLIFERATION of rat cardiac muscle cells declines rapidly during late embryonic and early postnatal development. Three to four weeks after birth, the total number of cardiac muscle cells is believed to be close to adult values, and further growth of the heart may be accounted for by the growth of the existing cardiac cells.1-1 However, one important question remains to be answered: are the individual cardiac cells "programmed" for a finite number of nuclear and cellular divisions for a given age or can the rate of proliferation previously observed during the early postnatal period be altered by other factors such as organ growth itself? Temporarily dissociating the growth-to-age relationship during the early postnatal period should provide an answer to the above question.The growth rate of the mammalian body is both agedependent and nutrition-dependent. In suckling rats, the number of young animals per litter is a decisive factor, because the source of food is limited to the mother. Thus, by varying the number of young rats per litter, the growth rate can be altered so that the body weight and heart weight may vary 2-4 times between the animals from the small litters (4 rats) and from the large litters (16 rats) when they are weaned at 21 days of age. This approach was used in our present experiments in order to study the effects of slow, normal, and accelerated body and heart growth rate on th...

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mentioning

confidence: 57%

The influence of aging and growth on the postnatal development of cardiac muscle in rats.

Rakusan

Raman²,

Layberry

et al. 1978

Circulation Research

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Response of the adult newt ventricle to injury

1974

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A study was made of the response of adult newt ventricle to injury. The major events in the repair process after wounding involve blood clot formation, coagulation necrosis, macrophagic activity, regenerative activity of heart muscle, and connective tissue formation. Light microscopic autoradiography indicated that there was a definite area of labeled cells in trabeculae adjacent to the wound, beginning at about ten days after injury. Electron microscopic autoradiography confirmed that myocytes containing myofibrillae underwent DNA synthesis. It was concluded that adult newt myocardium is capable of reacting to injury by the proliferation of myocytes at the wound area as indicated by both DNA synthesis and mitosis.

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DNA synthesis, mitosis and fusion of myocardial cells

Przybylski

Chlebowski

1972

Journal of Morphology

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Myocardial cells obtained from embryonic chick ventricles have been used to investigate (1) whether differentiated cells can undergo DNA synthesis and mitosis and, (2) whether heart cells when grown in culture can fuse with each other and with chick skeletal myoblasts to form heterokaryon myotubes. Electron microscopic observations have shown that myocardial cells of day 3 and day 20 chick embryos did contain myofibrils with defined sarcomeres; these cells have been observed i n mitosis. Cells obtained by tryptic digestion of day 12 chick ventricles when grown in culture continued to replicate their IjNA as shown by thymidine-SH radioautography with DNase controls and were observed in all stages of mitosis. Electron microscopy showed that myofibrils were present i n some of the cultured cells.Bi-, tri-and tetranucleate cells were observed in the cultures. Thymidine-SH radioautography showed that these cells were formed by karyokinesis without cytokinesis and by the fusion of uninucleate cells. Since the heart cells could fuse with each other, we tested the possibility that they could fuse with skeletal myoblasts to form heterokaryon myotubes. This was accomplished by co-culturing thymidine-"H labeled ventricular cells and unlabeled skeletal myoblasts. Radioautography with DNase controls showed that some of the myotubes consisted of unlabeled skeletal muscle nuclei and labeled heart nuclei i n varied proportions. The factors initiating the not been elucidated.

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Proliferation und Regeneration am Myokard

Cited by 50 publications

References 64 publications

The influence of aging and growth on the postnatal development of cardiac muscle in rats.

The influence of aging and growth on the postnatal development of cardiac muscle in rats.

Response of the adult newt ventricle to injury

DNA synthesis, mitosis and fusion of myocardial cells

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