Measurements of White Adipose Tissue Metabolism by Microdialysis Technique
The microdialysis method was introduced 25 yr ago to measure neurotransmitter concentrations in the brains of laboratory animals. For 10 yr, this technique has been adapted, in metabolic studies, to monitor the interstitial concentrations of small-mol-wt compounds present in the extracellular space of various tissues, specially skeletal muscle and adipose tissue (AT). This development concerned animal experiments, as well as clinical research in humans. The microdialysis probe mimics the passive function of an artificial small blood vessel implanted into the tissue (Fig. 1 ). The characteristics of AT microdialysis are as follows ( 1 ):
1. | It collects a representative sample of all substances in the extracellular fluid. |
2. | It causes minimal damage to the tissue. |
3. | It makes possible continuous sampling for hours or days after a single penetration of the tissue. |
4. | It allows recovery of endogenous substances, and makes them accessible to analytical techniques. |
5. | It permits introduction of exogenous substances in the tissue, in order to study the resulting local biochemical effect, and to avoid general effects. |
6. | It allows study of the local response inside the tissue during systemic drug administration, or when a physiological test is performed (such as exercise). |
Fig. 1. Schematic representation of a concentric microdialysis probe used for the measurement of AT metabolism.