Dietary lipid modulation of connective tissue matrix in rat abdominal aorta.

Dietary lipid modulation of structural and passive mechanical properties of isolated rat abdominal aortic segments were assessed during the early developmental period. Rats were raised from conception to 90 days of age on semisynthetic diets containing various types and amounts of lipids. Aortic segments from three groups of rats fed high-fat diets (15%, wt/wt) consisting of olive oil, corn oil, or lard as the sole lipid sources were compared with those from rats fed a low-fat control diet containing corn oil (5%, wt/wt). Morphometric analysis of the tunica media demonstrated that rats raised on diets with a relatively low polyunsaturated fatty acid content (olive oil and lard) had greater numbers of elastic lamellae than rats raised on diets with opposite fatty acid indexes (high- and low-fat corn oil). Changes in elastin content of the tunica media, determined biochemically, paralleled those seen by morphometric analysis of the elastic lamellar number. Altered dietary fatty acid ratios were also associated with changes in smooth muscle cell number. In this regard, a decreased cellular density was observed in the olive oil and lard diets compared with the corn oil diet. The olive oil diet was unique amongst the dietary lipid regimens in raising, whereas the lard-containing diet lowered, indexes of aortic tissue elasticity. These results demonstrate an effect of chronic feeding of high dietary fat on the composition and biomechanical properties of the connective tissue matrix of abdominal aortic rings from young Sprague-Dawley rats.