Serum-myocardium gradients of non-esterified fatty acids in dog, rat and man.

In the three species under investigation (dog, rat and man) a gradient from serum to heart tissue for total non-esterified fatty acids was assessed. The ratios serum/left ventricular tissue in dogs, serum/right auricular appendage in dogs, serum/whole heart tissue in rats and serum/right auricular appendage in man were found to be 6.4, 2.5, 5.6 and 2.8, respectively. The highest gradient was found for oleic acid, whereas no significant gradient for arachidonic acid could be detected. In the dog the arterio:local venous differences of non-esterified fatty acids across the left ventricular tissue correlated better with the serum/tissue ratio of non-esterified fatty acids than with the arterial non-esterified fatty acid level. Since the correlation coefficient (0.74) was still far from excellent, more factors than the non-esterified fatty acid serum/tissue gradient are likely to be involved in determining the extent to which non-esterified fatty acids are extracted by myocardial tissue.