Evaluation of the microdialysis technique in the dog fat pad

In the present study the microdialysis technique was evaluated in an isolat ed autoperfused dog fat pad. Concentrations of glucose, lactate, and glycer ol were measured in interstitial fluid by microdialysis and simultaneously in arterial and adipose venous plasma. Adipose tissue blood flow was measur ed by both Xe-133 washout-and timed weighing of venous blood. Metabolite co ncentrations in adipose venous plasma calculated from interstitial and arte rial metabolite concentrations and Xe-133 washout were positively correlate d with measured venous concentrations (glucose: r = 0.95, lactate: r = 0.92 , glycerol: r = 0.81). Calculated and measured venous plasma concentrations did not differ far either glucose or lactate, but for glycerol, calculated concentration was on average 76% of measured concentration. Metabolite exc hanges (Fick's principle) calculated from interstitial metabolite concentra tions were positively correlated with measured exchanges only for lactate ( r = 0.69). In conclusion, metabolite concentrations in adipose venous plasm a can be calculated from microdialysis measurements with greater accuracy f ar glucose and lactate than for glycerol. The precision, however, is too lo w to allow calculation of metabolite exchange when arteriovenous metabolite differences are low.