AGE- AND SEX-ASSOCIATED CHANGES IN CHEMICAL COMPOSITION OF BOVINE TRICEPS BRACHII INTRAMUSCULAR AND EPIMYSIAL CONNECTIVE TISSUE WITH EMPHASIS ON GLYCOSAMINOGLYCANS

Abstract

Age-related changes were studied in the bovine intramuscular and epimysial connective tissue components from animals ranging in age from fetuses to 8.9 yr and from 1.2 to 8.9 yr, respectively. Intramuscular concentration of nitrogen increased (P < 0.05), while intramuscular concentrations of collagen and glycosaminoglycans (GAG) decreased (P < 0.05) with age until the animals were yearlings. Epimysial concentration of collagen increased and that of GAG decreased (P < 0.05) with age in the postnatal animals. Maturation was associated with decreasing (P < 0.05) amounts of labile collagen, hexosamine, and sialic acid in both tissues and occurred earlier in intramuscular than in epimysial tissue. Epimysial tissue from males contained more (P < 0.05) collagen and less (P < 0.05) labile hexosamine than epimysial tissue from females of a similar age. Hyaluronic acid and dermatan sulfate were the major GAG in bovine skeletal muscle with small amounts of heparan sulfate, chondroitin 4-sulfate, chondroitin 6-sulfate and heparin. Hyaluronic acid:dermatan sulfate weight ratios were greater (P < 0.05) in the intramuscular than in the epimysial tissues. The ratio values were 2.0–2.7 in intramuscular tissues, while in the epimysial tissues, the values were 0.5–0.6 in the yearlings and young adults and 0.9 in the mature adults. In postnatal animals, intramuscular tissues were associated with a smaller (P < 0.05) proportion of chondroitin 6-sulfate in the total GAG than were epimysial tissues. Both hyaluronic acid and dermatan sulfate concentrations decreased (P < 0.05) during fetal and early postnatal growth in the intramuscular tissue, while in the epimysial tissue, dermatan sulfate concentrations gradually decreased (P < 0.05) with age in the postnatal animals. Skeletal muscle maturation was associated with an increased (P < 0.05) stability of connective tissue and a decreased (P < 0.05) amount of total GAG and glycoproteins.