Evaluation of the microdialysis ethanol technique for monitoring of subcutaneous adipose tissue blood flow in humans.

OBJECTIVE: To investigate the feasibility of the microdialysis ethanol perfusion technique for monitoring nutritive blood flow in subcutaneous adipose tissue. RESEARCH DESIGN AND METHODS: Microdialysis probes were inserted percutaneously into the subcutaneous adipose tissue in 15 non-obese women, and were perfused with 50 mmol/l of ethanol. The experiments were carried out during basal conditions and in conjunction with local vasodilation induced by external heating. The ethanol exchange ratio (ethanol concentration in the outgoing tissue dialysate vs ethanol concentration in the ingoing perfusate) was determined. A comparison was made with the 133Xe clearance technique to assess the adipose tissue blood flow.
RESULTS: At rest, the ethanol exchange ratio in the individual subjects was inversely correlated to the adipose tissue blood flow, as measured with 133Xe wash-out (r = -0.78-0.82, p < 0.05-0.01). When the subcutaneous temperature was increased in a stepwise fashion by external heating, adipose tissue blood flow, as determined with 133Xe clearance, was increased by about 50% and 100%, respectively, above resting values (F = 26.7, p < 0.0001). At the same time, the ethanol exchange ratio was progressively and significantly (F = 24.6, p < 0.0001) reduced. In the individual subjects there was a close negative correlation (r = -0.90-0.94) between the ethanol exchange ratios and the corresponding adipose tissue blood flow values, as measured by 133Xe clearance, in response to local vasodilation.
CONCLUSION: The microdialysis ethanol perfusion technique provides a valid indicator of small changes within the physiological range in adipose tissue blood flow.