DIETARY LIPIDS MODIFY THE FATTY-ACID COMPOSITION OF CARTILAGE, ISOLATED CHONDROCYTES AND MATRIX VESICLES

The effects of dietary lipids on the fatty acid composition of hyaline cartilage, epiphyseal chondrocytes (EC) and matrix vesicles (MV) were evaluated in chicks. A basal semipurified diet was fed to chicks cont aining one of the following lipid sources at 70 g/kg: soybean oil, but ter + corn oil, margarine + corn oil or menhaden oil + corn oil (MEC). Articular and epiphyseal growth cartilage were isolated from the prox imal tibiotarsus; EC and MV were subsequently released by trypsin (EC 3.4.21.4) and collagenase (EC 3.4.24.3) digestion followed by ultracen trifugation. The fatty acid composition of polar lipids in chick epiph yseal cartilage at three and six weeks, as well as articular cartilage , EC aad MV at eight weeks of age revealed the presence of high levels of saturated and mono unsaturated fatty acids (up to 85.5%) but low l evels of n-6 polyunsaturated fatty acids (PUFA) (2.6-10.2%). Mead acid (20:3n-9, >3%) was also present in cartilage, EC and MV lipids, and w as unaffected by the dietary lipid treatments. Total n-3 PUFA concentr ations were the highest in cartilage, EC and MV of chicks consuming ME C. Feeding MEC lowered the levels of 20:4n-6 in cartilage, but increas ed 20:5n-3 levels. The data are consistent with those reported previou sly which showed that cartilage tissues are low in n-6 PUFA and that t hey contain 20:3n-9. We furthermore demonstrated that the PUFA composi tion of cartilage can be modified by dietary lipids.