The determination of lipids and proteins in suction blister fluid

The concentration of 5 different proteins in suction blister fluid and serum was determined by immunotechniques. These proteins, varying in size and molecular weight (6,600-2,300,000) were insulin, albumin, high density lipoprotein determined as apoprotein A-I, alpha 2-macroglobulin and low density lipoprotein measured as apoprotein B. The difference in the blister fluid/serum concentration ratio of the proteins was dependent on the molecular weight and followed mainly the law of diffusion. Moreover, the amounts of insulin, albumin and apoproteins A-I and B in suction blister fluid were the same as those reported in peripheral lymph. The results indicate that the sieve function of the capillary basement membrane remains intact during the formation of the suction blisters. Suction blister fluid might therefore be regarded as representative of interstitial fluid. The concentrations of 4 different lipids (cholesterol, cholesterolesters, triglycerides and phospholipids) were also determined and their blister fluid/serum concentration ratio proved to have a fairly constant value of 0.25.