[Inestability of fatty acid desaturation enzymes in liver slices (author's transl)].

A study was made on the microsomal oxidative desaturating activity of fatty acids in rat liver slices incubated in different media. [1-14C] linoleic acid desaturation activity decreased during the incubation in Krebs-Ringer-Bicarbonate. The addition of glucose or pyruvate in the incubation medium did not alter the decrease of the linoleic desaturation activity compared to the controls. Linoleic desaturation to gamma-linolenic acid descreased even when the slices were incubated in different media and at different temperatures. However, the inclusion of aminoacids in the media prevented the decrease of linoleic acid desaturation. Microsomal stearic acid desaturation to oleic acid in liver slices was less modified by incubation than linoleic acid desaturation. Glucose inclusion in the medium enhanced 9-desaturation. The stability of the desaturases in the liver slices is discussed. The results evidence once more that 9-desaturation and 6-desaturation are accomplished by different enzymes controlled by separate mechanisms.