Development of certain morphometric parameters of rat cardiac muscle cells
Juríková, Z.; Vlcek, D.; Becke, R.; Martínek, J.; Gaier, N.
Folia Morphologica 32(2): 105-112
1984
ISSN/ISBN: 0015-5640 PMID: 6469137 Document Number: 230111
A morphometric evaluation of partial mitochondrial and myofibril volume in the cells of the rat myocardium during early postnatal development (at 5, 9, 14, 19 and 35 days) an in adult animals is presented. Statistically significant shifts occurred between the 19th and the 35th day in the proportion of mitochondria, which here attained values of 0.376 .+-. 0.035, corresponding to the values in adult animals (0.349 .+-. 0.054). In the case of the myofibrils, a similar shift to adult values (0.540 .+-. 0.062) did not occur until after the 35th day. After a cyclophosphamide [CPA] load of the myocardium from the age of 75 days, in 15, 30 or 40 doses of 10 mg/kg (5 doses/wk), the first sign of adaptation was an increase in the volume proportion of the mitochondria in the experimental group given 30 doses of CPA, to a value of 0.441 .+-. 0.077, whereas relative myofibril volume fell to 0.456 .+-. 0.28. The reciprocal ration of the mitochondria and myofibrils evened out in the 3rd group (40 doses of CPA), but with the difference the section size of the cardiac cells grew to almost 2-fold the control value. The course of stress-induced changes in the myocardium of adult animals is in general similar to the development of mitochondrial and myofibril volume relationships in the early postnatal phase. In the 1st phase they are manifested in an increase in mitochondrial partial density, followed in the 2nd phase, in keeping with the development of anabolic processes, by an increase in myofibril partial density.