Proteoglycans, DNA, and RNA in rat granulation tissue, skin, and aorta. Biochemical and histological studies

Proteoglycans in skin and aorta and nucleic acids in skin were studied in rats with subcutaneous sponge implants and in unoperated rats and compared with the sponge induced granulation tissue during a 42 day period. In rat aorta there was a predominance of the sulphated glycosaminoglycans, in particular heparan sulphate, while in skin there was a predominance of hyaluronic acid and dermatan sulphate. The subcutaneous sponge implantation caused a decrease in the dry weights of skin and aorta but did not influence the concentrations of the measured variables. In aorta the concentrations of chondroitin sulphate and dermatan sulphate decreased with age while in skin there was a slight fall in the concentrations of hyaluronic acid and heparan sulphate with age. The rate of biosynthesis of proteoglycans as estimated from the 35S-sulphate uptake was higher in skin than in aorta. A sequential development was noticed in granulation tissue with an initial high content of hyaluronic acid followed by increasing amounts of chondroitin sulphate and dermatan sulphate in older granulation tissue. The RNA/DNA ratio reached a maximum in 14 day old granulation tissue, but was unchanged in skin throughout the 42 day period. It is concluded that the distribution of proteoglycans and nucleic acids differs from tissue to tissue. This may be of relevance for tissue differences in susceptibility to diseases and to the effects - and side-effects - of drugs. The morphological and biochemical development of sponge induced granulation tissue from rats was similar to other types of granulation tissue during the first 4 weeks.