Relationship between the number and position of methyl groups on fatty acid analogues and myocardial metabolism

The effects of the number and position of methyl groups on radioiodinated fatty acids (IFAs) on myocardial uptake and metabolism were investigated. Four IFAs: 16-iodo-2-methyl (αM-IHA), 16-iodo-3-methyl (βMIHA), 16-iodo-2,2-methyl (α2M-IHA) and Iodo-hexadecanoic acids (IHA), all of them were labeled by 131I and injected into a vein in the tail of the mouse. groups of at least 5 mice were killed at 30, 60, 150, 300 and 600 second post-injection. The cardiac and blood radioactivity were measured. The heart was homogenized and separated into the aqueous and organic phase and the latter was again separated into free fatty acid. diglycerides and triglycerides by thin layer chromatography. The myocardial clearance rate of four IFAs in turn was IHA>α2M-IHA>αM-IHA>βM-IHA βM-IHA>α2M-IHA>IHA and α2M-IHA>IHA = αM-IHA βM-IHA. Compared with IHA, methyl-branched-IHA showed much longer myocardial retention in mice. Of three methyl-branched-IHA, βM-IHA had lowest clearance rate from mice hearts