CUTANEOUS MICRODIALYSIS IN THE RAT - INSERTION TRAUMA STUDIED BY ULTRASOUND IMAGING

Microdialysis is a method by which compounds can be studied in the ext racellular space in skin, in vivo. The microdialysis probe is inserted in the dermis using a guide cannula. It is expected that intradermal oedema associated with insertion trauma as well as the probe depth can influence the results of microdialysis studies. The aim of the presen t study was to assess the effects of insertion trauma and, additionall y, the probe depth by ultrasound. High-frequency (20 MHz) ultrasound i s a non-invasive method for measuring the thickness and echostructure of skin. Hairless rats were anaesthetized with either halothane (n = 7 ) or pentobarbital sodium (n = 6). The insertion of the microdialysis probe resulted in a 38% relative increase in skin thickness. At 120 mi n the skin thickness had not reached the pre-insertion value. Thus, si gnificant skin thickening, representing traumatic oedema, developed du e to insertion of the microdialysis probe in the skin. The microdialys is probe could be inserted reproducibly in the lower dermis.