The Fate of ¹³¹I-17-lodohepta-decanoic Acid During Lactate Loading: Its Oxidation is Strongly Inhibited in Favor of its Esterification

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 myocardial¹³¹I-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 < 0.0001, Student’s t- test). Thin-layer chromatography of cardiac lipids demonstrated that the nonoxidized ¹³¹I-17-HDA was mainly stored in the triglycerides and phosphoglycerides. These results suggest that lactate inhibits cardiac ¹³¹I-HDA oxidation.

Zusammenfassung

Der Einbau von ¹³¹J-17-Jod-Hepta- dekansäure (¹³¹J-17-HDA) wurde am gesunden Hundeherz unter Kontroll- bedingungen (n = 8) und nach Zugabe von Laktat (n = 7) untersucht. Der Gesamtwert der myokardialen ¹³¹J-17- HDA-Aufnahme war unter Laktatinfusion unverändert. Die Oxidation verringerte sich um das Fünffache (gemessen am freien ¹³¹J-Jodid), nämlich von 70 auf 14% (p <0,0001). Die Dünnschicht-Chromatographie der myokardialen Lipide zeigte, daß nicht- oxidierte ¹³¹J-17-HDA hauptsächlich in Triglyzerid und die Phosphorglyzeride eingebaut wurde. Diese Ergebnisse weisen auf eine Laktat-vermittelte Inhibition der Oxidation von ¹³¹J-17- HDA hin.

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