Partition of Unesterified Fatty Acids in Normal and Nephrotic Syndrome Serum and Its Effect on Serum Electrophoretic Pattern1

Abstract

Albumin- and lipoprotein -bound unesterified fatty acids (UFA) were measured on albumin separated at 60%, saturation with ammonium sulfate as well as on lipoproteins isolated by ultracentrifuged flotation. In 10 normal sera 77.6% ([plus or minus] S. D. 7.8) of total serum UFA was found on albumin (ammonium sulfate method), while 13.3-29.8% was titrated on lipoproteins floated from 6 other sera. Despite the normal total UFA content of nephrotic sera the proportion of UFA bound to lipoproteins was considerably higher than in normal sera. In 12 nephrotic sera only from 23.6 to 54.3% of total serum UFA was found on the salt-separated albumin, while in 5 other sera 23.7 to 50.8% was found in the lipoproteins. The competition of albumin and lipoproteins for available UFA was illustrated by the fact that partition of UFA was dependent on the lipoprotein to albumin concentration ratio in the serum. The electrophoretic resolution of alpha and beta globulins, as well as UFA partition in nephrotic serum, was restored toward normal by the in vitro addition of UFA-poor albumin. This was due to the decrease in the electrophoretic mobility of the beta lipoprotein component in the albumin enriched serum, as shown in moving boundary and filter paper separations. Thus, the increased UFA content of the lipoproteins may be the principal cause of excess lipoproteins appearing ahead of beta zone in the electrophoretic pattern of sera with grossly distorted lipoprotein to albumin ratios.