Evidence for a detectable delta-6-desaturase activity in rat heart microsomes: aging influence on enzyme activity

This study represents the first report indicating that rat heart microsomes contain a measurable delta-6-desaturase activity. The aging process affects delta-6-desaturase activity in the heart to a lesser extent than in the liver, supporting the hypothesis that the regulation of the individual desaturase enzymes may differ in these two tissues. Although decreased desaturase activity, considered alone, may be expected to lower polyunsaturated fatty acid levels, in old animals no modifications in heart microsome fatty acid composition were observed. Probably other metabolic changes may offset this effect, leading to the maintenance of arachidonic acid level in the heart.