INCREASED SARCOLEMMAL PERMEABILITY IN CARDIOMYOPATHY IN HYPERTROPHIED SHR MYOCARDIUM

• Published in: Journal of Toxicologic Pathology Vol. 7; no. 2; pp. 191 - 198
• Main Authors: Mikinori Torii, Satoshi Inoue, Shuuichi Matsushima, Satoshi Fuji, Toshiyuki Maruyama, Yoshihiro Muraoka, Hiroyuki Ito
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society of Toxicologic Pathology 1994
• ISSN: 0914-9198; 1881-915X

To study the membrane changes in the myocardium, the sarcolemmal permeability of 16week-old SHR and age-matched WKY myocardium was examined morphologically using horseradish peroxidase (HRP) on the first and fourth day after doxorubicin administration. No HRP was seen in either saline-treated controls or doxorubicin-treated WKY on the first day. On the fourth day, the doxorubicin-treated WKY showed, HRP around the myocytes due to an increase in the vascular permeability, whereas, the HRP-reactant product was not seen within the sarcoplasm. Electron microscopy revealed osmiophilic, fine granular HRP-reactant products in the extracellular space of the WKY myocardium on the fourth day. On the other hand, in doxorubicin-treated SHR myocardium, HRP was seen in a portion of the papillary muscle or myocardial cells in the anterior wall on the first day and HRP-positive myocytes were scattered in the anterio-lateral wall at the fourth day. Cross striations were still visible within some HRP-positive myocytes of SHR. Electron microscopy also showed HRP-reactant products, not only in sarcotubules of normal-appearance myocytes, but also in myofibrils and/or mitochondria of highly degenerated myocytes. These results demonstrate the increase in the membrane permeability in the SHR myocardium, probably due to genetical disadvantage of the defense system and a proneness for membrane lipid peroxidation.