The fate of 131I-17-iodoheptadecanoic acid during lactate loading: its oxidation is strongly inhibited in favor of its esterification. A radiochemical study in the canine heart.

The influence of lactate loading on fatty acid metabolism (pH = 7.4) by the normal canine heart was investigated radiochemically using the radioiodinated fatty acid 131I-17-iodoheptadecanoic acid (131I-17-HDA). Fatty acid metabolism was studied during control conditions (n = 8) and after lactate loading (n = 7). In the canine heart total myocardial 131I-17-HDA radioactivity (uptake) was not changed during the lactate intervention. The oxidation decreased fivefold (measured as free 131I-iodide ion) from 70% to 14% (p less than 0.0001, Student's t-test). Thin-layer chromatography of cardiac lipids demonstrated that the non-oxidized 131I-17-HDA was mainly stored in the triglycerides and phosphoglycerides. These results suggest that lactate inhibits cardiac 131I-HDA oxidation.