IN-SITU MICRODIALYSIS FOR MONITORING OF EXTRACELLULAR GLUTATHIONE LEVELS IN NORMAL, ISCHEMIC AND POSTISCHEMIC SKELETAL-MUSCLE

Microdialysis probes were inserted into the tibialis anterior muscle a nd into the femoral vein of anaesthetised Sprague-Dawley rats for moni toring of reduced (GSH) and oxidized (GSSG) extracellular glutathione. The dialysates were analysed using HPLC. The levels of GSH and GSSG w ere high immediately after implantation in the skeletal muscle and dec lined to steady state levels after 90 minutes into the same range as t hat found in the venous dialysate. Total ischemia was induced two hour s after implantation of the dialysis probe after steady state levels h ad been reached. The extracellular levels of GSH increased during tota l ischemia and had doubled at the end of the ischemic period compared to preischemic values. During the following initial 30 minutes of repe rfusion the levels increased further to four-fold the preischemic leve ls. The levels of GSSG also increased (100%) during the initial 30 min utes of reperfusion. The extracellular GSH levels remained elevated fo r 1 hour of reperfusion, but the GSSG levels returned to preischemic l evels. The results indicate that intermittent hypoxia or anoxia in mus cle tissue through hypoperfusion or ischemia decreases intracellular G SH stores by leakage, reducing the intracellular antioxidative capacit y and increasing the risk for oxidative reperfusion injury upon final normalization of tissue blood supply.