Immunochemical quantitation of fatty acid-binding proteins. Tissue distribution of liver and heart FABP types in human and porcine tissues

Abstract

1. Antisera against heart and liver fatty acid-binding proteins (FABPs) were used in enzyme-linked immunosorbent assay to study the cross-reactivity between these FABP types of man, pig and rat, and to assess their tissue distribution in man and pig. 2. No cross-reactivities were found of heart FABPs with anti-liver FABP sera and vice versa. With the liver FABPs, marked species differences were found, but the three proteins are clearly related. Human and pig heart FABP are immunochemically closer related to each other than to this protein from rat heart. 3. The tissue distribution of the heart and liver FABP types is similar in man, pig and rat. Liver FABP is only found in liver and intestine, and heart FABP is present in heart, skeletal muscle, kidney, lung, brain and placenta. 4. Cardiac FABP is also found in cultured human and rat endothelial cells. 5. The FABP content of human and pig liver is comparable to that of rat liver, but the tissue concentrations of heart FABP are lower in man and pig than in rat. When the latter values are expressed relative to the FABP content in heart, analogous distribution patterns are observed in man, pig and rat.