Injury produced by free fatty acids to lysosomes and mitochondria in cultured heart muscle and endothelial cells

Four-day primary coverglass cultures of rat heart muscle (M) and endothelioid (E) cells were treated for 30 min with stearic, oleic or linoleic acids in a FFA/albumin ratio of 6:1 at concentrations from 5 × 10⁻⁶ M to 5 × 10⁻⁴ M. Labilization of lysosomes and mitochondria was measured by acid phosphatase and succinic dehydrogenase staining activity respectively.

Stearate or linoleate, but not oleate, labilized M cell lysosomes at 5 × 10⁻⁶ M. Lysosomes of E cells were not significantly affected by any of the FFA at 5 × 10⁻⁴ M. The order of activity of these FFA for M cell lysosomes was LINOLEATE = stearate > oleate.

Both E and M cell mitochondria were significantly labilized by oleate or linoleate, 5 × 10⁻⁶ M, and by stearate, 5 × 10⁻⁵ M. The order of activity was linoleate > oleate > stearate.

Treatment of cultures for 24 hr with 50 μg/ml of hydrocortisone before the FFA at 5 × 10⁻⁵ M provided significant protection only against stearate-induced lysosomal labilization.