The biochemical and morphological study of the cytoskeleton and extracellular matrix of rat heart was carried out after single injection of
adriamycin (2.2 or 0.44 mg/kg). Hearts were taken for the study after 2 hours and 3 weeks after injection. The light and electronic microscopy, immunohistochemical determination of type I, III and IV
collagens and
fibronectin using specific
antibodies were implied for morphological study; electrophoresis and immunoblotting were implied for the determination of the content of some
proteins of cardiomyocytes (KRP or
telokin,
desmin,
tubulin and
vinculin), and extracellular matrix (
fibronectin) and vascular smooth muscle cells (MLCK,
myosin light chain kinase).
Adriamycin injection in the dose 2.2 mg/kg which is close to therapeutic and known to alter intracellular membranes approximately in the half of cardiomyocytes, did not influence the relative volume and structure of
collagen network but distinctly reduced the density of
fibronectin-distribution. The content of
tubulin,
fibronectin, MLCK and KRP was significantly decreased by 18-24%, while contents of
desmin and
vinculin were changed insignificantly. After 3 weeks, an increased density and extension of
collagen network indicating the development of diffuse
fibrosis were observed. Contents of
tubulin and KRP were increased above control level by 50 and 20%, respectively. Similar hyperrestitution of
tubulin,
fibronectin and KRP content by 15-25% was determined after smaller dose of
adriamycin (0.44 mg/kg). Only content of MLCK out of
proteins studied remained at lower level in both groups by 25-34%. Isolated chick embryo cardiomyocytes subjected to
adriamycin responded by increased level of KRP expression by 20% in 4 days while the level of
tubulin expression remained unchanged. Results showed that damage of cardiomyocytes and extracellular matrix after single injection of
adriamycin in the dose close to therapeutic was followed by increased expression of some
proteins of cytoskeleton and extracellular matrix. KRP seems to play active role in this reparative response while the steadily reduced level of MLCK expression may disturb the control of coronary vessels.