Sampling from a suction induced mini-erosion in human skin. Methodological studies.

Dermal interstitial fluid (IF) was extracted serially and painlessly by brief suction for as long as 6 days. The erosion was otherwise kept occluded, Sample volumes exceded those required for measuring a wide range of biological substances. Epidermal regeneration was rapid.

Glucose concentrations in IF and plasma, measured in diabetic and non-diabetic subjects for as long as 6 days were closely correlated over a wide range of values. During oral glucose tolerance tests on days 1 and 3 after forming the erosion, the IF OGTT curves for glucose, 3-hydroxybutyrate and glycerol were very similar to plasma. IF lactate curves were higher than in plasma, reflecting glycolytic activity , whereas insulin curves were lower, reflecting vascular permeability. A potential is suggested for clinical sampling of glucose in subjects with diabetes mellitus, and for experimental monitoring of dermal metabolism.

The IF concentration of plasma proteins (size range 6-720 kDa) measured in IF on day 1 in healthy volunteers was consistent with findings obtained with other techniques. From day 2 to 5, the sample fluid reflected a steady state of increased permeability induced by mild inflammation. IF samples extracted on day 1 using greater negative pressure had lower protein concentrations than those extracted at lower pressure, indicating an increased water fraction and an intact sieve function of the vascular wall. The differences were less pronounced on days 2-5. Extraction volumes were dependent on the extraction pressure on all days.

The findings indicate the usefulness of the technique for clinical experimental purposes.