Comparative study of cardiac muscle structure between two models of chronic cor pulmonale induced by hypoxia and active immunization of M2-muscarinic receptor / 中华老年医学杂志

ABSTRACT

Objective To compare the similarities and differences in changes of cardiac muscle structure between the rat models of chronic cor pulmonale induced by hypoxia and active immunization of M2-muscarinic receptor under light microscope and electron microscope, and to explore the dependablity of the antibody effects on cardiac architecture. Methods The 48 healthy male Wistar rats were randomly divided into 4 groups (1) Hypoxia group the typical model of chronic cor pulmonale was established according to XUE's method; (2) Active immunization group was immunized by M2-muscarinic receptor peptide; (3) Control group was fed in normal condition; (4) Cyclosporin A group the hypoxia group plus cyclosporin A treatment at the same time. The antibody against M2-muscarinic receptor was detected by SA-ELISA, and the pathological exemplar of cardiac muscle was observed by light microscope and transmission electron microscope. Results (1) Antibody level of M2-muscarinic receptor; the P/N values gradually increased along with the process of experiment, and the max value in active immunization group was 5. 13. At the end of the second week, the value in hypoxia group increased to 2.08, but was still less than in active immunization group (4.66). (2) Under light microscope in hypoxia group and active immunization group, the hearts displayed significant alterations including disorder of cardiac muscle fiber, necrosis of myocardial cells together with the infiltration of inflammatory cells. There were no differences in light microscopic findings between hypoxia and cyclosporin A group. (3) Under transmission electronic microscope examination in both active immunization group and hypoxia group, the hearts showed s1imilar significant alterations such as focal cardiac muscle fiberlysis, loss of normal muscle fiber banding pattern, mitochondrial swelling and condensation, sarcoplasmic vacuolation and deposition of dense granules in both the sarcoplasmic and muscle fiber. The contour of myocyte was irregular and plasma membranes were discontinuous in some cells. All altered myocytes were fairly widely distributed throughout the myocardium. The interstitium showed edema, deposits of flocculent serum protein, activated fibroblasts and increased amounts of collagen fibers. No obvious alterations were observed in cyclosporin A group. Conclusions The positive rate and the titer of antibody against M2-muscarinic receptor are obviously increased in the rat model of chronic cor pulmonale, which indicates that there is a relationship between the antibody against M2-muscarinic receptor and the pathogenesis of chronic cor pulmonale.