What are the symptoms of myolytic disease

In daily life, many people prefer high-salt, high-fat and irritating foods. Such long-term living habits will cause great harm to the body. Myolytic disease may occur due to muscle compression caused by fixed posture, frequent and excessive exercise, high-voltage electric shock, systemic spasm, etc. Rheumatoid arthritis is also a disease in which muscle cells in the human body die.

Question 1

Rhabdomyolysis is a disease in which muscle cells produce toxic substances, leading to kidney damage, commonly known as muscle dissolution. There are three types of muscles in the human body: cardiac muscle, smooth muscle, and skeletal muscle. The cardiac muscle and skeletal muscle are striated. Rhabdomyolysis usually occurs in the skeletal muscles related to our limb movements. Rhabdomyolysis often occurs after a muscle is hit hard, compressed for a long time, or overused. In a few other cases, such as blood vessel blockage leading to muscle hypoxia, and patients with special body conditions taking certain medications, rhabdomyolysis may also be caused.

(I) Biochemical changes in muscles

⒈Contractile proteins and metabolism

Myosin can be divided into insoluble collagen and soluble myofibrillar protein based on whether it is soluble in alkaline solution at room temperature. The latter accounts for more than 90% of normal adult muscle. In myopathy, soluble protein decreases, reaching less than 50% in the late stage, while connective tissue collagen increases. In the muscles of pseudohypertrophic muscular dystrophy, the ATPase activity of myosin is decreased, and the ability of actomyosin to bind Ca2+ is lower than that of normal people. The protein synthesis rate in the ribosomes extracted from the muscles of people with myopathy or gene carriers is higher than that of normal people. The automatic radiography method detects that the rate of leucine incorporation into protein in the sarcoplasm of patient muscles is faster than that of normal people. Using 3-methylhistidine, the main component of actin and myosin, as an indicator, it was found that the amount excreted in urine of children with pseudohypertrophic myopathy is 3 times higher than that of normal children of the same age, indicating that the synthesis rate of myosin increases in myopathy.

⒉ Muscle enzymes

In the early stage of myopathy, the activities of enzymes such as cathepsin A and B, dipeptidase, arylthioesterase and ribonuclease are significantly increased, while the activities of enzymes such as cathepsin D, acid phosphatase, β-acetylglucosaminidase, fucosidase and mannosidase only begin to increase in the late stage of myopathy. It is generally believed that this is a nonspecific and secondary change, which is the response of muscle fibers to some harmful factors. In terms of glycolysis and sugar metabolism enzymes, it was first discovered that the glycolysis rate of muscles of myopathy patients was lower than that of normal people, and then it was discovered that the activities of α-phosphorylase, phosphoglucomutase (PGM) and aldolase were decreased, and the aldolase activity was only less than half of that of normal people. There was also a significant decrease in CPK and ATPase, especially in the juvenile type. The activities of adenylate kinase (AK), AMMP deaminase, LDH, pyruvate kinase (PK) and glyceraldehyde phosphate dehydrogenase (GAP-DH) were also lower than those in normal muscles, while the activities of 6-phosphoglucose dehydrogenase and 6-phosphoglucuronic acid dehydrogenase were increased, indicating that the pentose phosphate pathway was active. This is because the growth of regenerating fibers in muscles requires more nucleic acid synthesis. LDH5 only accounts for 17.7% of LDH in the muscles of patients with muscular dystrophy (normal is 31.4%), which is significantly decreased, while CPK-MM is higher than that in normal muscles. Abnormal hexokinase type II (HK-II) occurs in pseudohypertrophic myopathy.