Growth Hormone and Liver Mitochondria: Time Course of Effects on Respiration and Fatty Acid Composition in Hypophysectomized Rats*

The time course of the effects of GH on state 3 respiration and fatty acid composition of liver mitochondria was investigated up to 48 h after an injecton of bovine GH to hypophysectomized rats. The respiratory rate increased significantly by 12 h, whereas the docosahexaenoic acid level, the total unsaturation index, and the ratio of arachidonic acid to linoleic acid of total phospholipids increased as early as 4 h after the hormone injection. A linear association was found between the respiratory rate and the three measures of fatty acid composition. It is concluded that the hormonal effects on respiration may be partly mediated through changes in fatty acid composition, which have an additive effect on increased synthesis of proteins and respiratory chain components. (Endocrinology 119: 250–252,1986)