α-Oxidation of endogenous fatty acids in fresh potato slices

Abstract

The respiration of fresh potato slices is inhibited up to 30% by imidazole, an inhibitor of α-oxidation of long chain fatty acids; it is stimulated approximately threefold by the uncoupler, carbonylcyanide m-Cl-phenylhydrazone (m-Cl-CCP). The stimulation by m-Cl-CCP is totally inhibited by imidazole. The release of 14CO2 from car☐yl-labelled long chain fatty acids is also stimulated by m-Cl-CCP in fresh slices, and inhibited by imidazole. The δ13C value of fresh tissue respiratory CO2—indicative of the 13C/12C ratio of the endogenous respiratory substrate—indicates lipid to be the predominant substrate in fresh slices, as well as in fresh slices treated with m-Cl-CCP. Aged slices are considerably less imidazole sensitive in all the above respects. The substrate for aged slice respiration as indicated by δ13C values is carbohydrate. The basal respiration in fresh potato slices apparently involves considerable lipid oxidation of a mixed nature, while the respiratory increment in the presence of m-Cl-CCP represents predominantly α-oxidation of long chain fatty acids.