Differences in the synthesis and secretion of sulfated glycosaminoglycans by aorta explant monolayers cultured from atherosclerosis-susceptible and -resistant pigeons.

The synthesis and secretion of sulfated glycosaminoglycans (GAGs) by aorta explant monolayers cultured from atherosclerosis-susceptible White Carneau (WC) and atherosclerosis resistant Show Racer SR pigeons have been compared. Primary cultures of WC pigeon aorta incorporation three to four times as much 35-S-sulfate into trichloroacetic acid (TCA) soluble, nondialyzable material that is over 90% sensitive to chondroitinase ABC digestion when compared with parallel cultures of SR pigeon aorta. Qualitatively, the GAGs produced by WC and SR aorta explants were similar in that their electrophoretic profiles were characterized by a prominent slow migrating band that did not coelectrophorese with known GAG standards, a discrete hyaluronic acid and heparan sulfate band and a broad band containing dermatan sulfate and chondroitin 4- and 6-sulfate. Enzyme digestion of the labeled material revealed that cultures of each breed synthesized and secreted predominantly chondroitin sulfate (approximately 60%) with moderate amounts of dermatan sulfate (approximately 35%) and little heparan sulfate (< 5%). This pattern of GAG distribution resembled that of GAGs present in pigeon aortas in vivo. Although differences in the relative percentages of each type of GAG produced by aorta explant cultures from each breed were not evident, densitometric tracings and radioisotopic activity of the electrophoretically separated GAGs indicate more sulfated GAG of each type present in WC as compared with SR cultures. Glycosaminoglycan-containing proteoglycans were also demonstrated morphologically in the aorta explant monolayers of each breed and resembled aortic proteoglycans in vivo. Proteoglycans in vitro existed as discrete 200-500-A polygonal granules, exhibited a marked affinity for ruthenium red, were intimately associated with each other through filamentous projections as well as with other components of the intercellular matrix (collagen and elastic fiber), and were completely sensitive to chondroitinase ABC digestion. This culture system is offered as a useful model for future investigations concerned with relating GAG metabolism to susceptibility to atherosclerosis.