Total Proteoglycan Research Articles

Regulation of chondrosarcoma metabolism by cyclic adenosine 3'5'-monophosphate.

The in vitro effects of cyclic AMP on amino acid transport and synthesis of macromolecules in the Swarm rat chondrosarcoma were investigated using the cyclic AMP analogue, N6-monobutyryl cyclic AMP (MBcAMP), and the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (MIX). Amino acid transport was assessed by measuring alpha-amino-[1-14C]isobutyrate (AIB) uptake. The synthesis of macromolecules was estimated by measuring radiolabeled precursor incorporation into total proteins, proteoglycan, and RNA. MBcAMP stimulated [14C]AIB uptake, [3H]uridine transport, and UTP formation. MBcAMP inhibited 35SO4 and [3H]leucine incorporation into proteoglycan and stimulated [3H]uridine incorporation into RNA. MIX elevated endogenous cyclic AMP levels in the Swarm rat chondrosarcoma and mimicked the effects of MBcAMP on AIB transport and radiolabeled precursor incorporation into macromolecules. For comparative purposes, the effects of MBcAMP on AIB uptake and macromolecule synthesis in rat costal cartilage segments were investigated. MBcAMP and MIX stimulated AIB uptake by costal cartilage segments, inhibited [3H]leucine incorporation into total protein and 35SO4 incorporation into proteoglycan, and had no effect on [3H]uridine incorporation into RNA.

Comparison of proteoglycans from bovine articular cartilage

Four bovine articular cartilages have been compared with regard to the chemical composition of the whole cartilages, the amount of proteoglycan selectively extracted with 3 M MgCl 2 or with 3 M guanidine·HCl, and the compositions and physical properties of the isolated proteoglycans. The whole cartilages differ but slightly in composition. Occipital condylar cartilage, a thin cartilage from the smallest joint, contains 4% more collagen and proportionately less proteoglycan than proximal humeral, the thickest cartilage from the largest joint. Each cartilage contains a pool of proteoglycan that resists extraction with 3 M MgCl 2 but is extracted with 3 M guanidine·HCl. The proteoglycan extracted from each cartilage with 3 M guanidine·HCl contains a high molecular weight proteoglycan-collagen complex demonstrated by analytical ultracentrifugation and by the turbidity of its visible and ultraviolet spectra. The four cartilages appear to differ most remarkably in the fraction of total proteoglycan extracted from each as proteoglycan-collagen complex.