Cellulr restitution after 3 h of complete tourniquet ischemia.

The refinement of techniques for extremity surgery makes it urgent to get more information at cell level of the effects of tourniquet times exceeding the usually accepted 90--120 min. Therefore, in the present experiments, the cellular metabolic and functional restitution of canine skeletal muscle after 3 h of complete tourniquet ischemia was studied. During the ischemia and after recirculation, repeated skeletal muscle samples were taken for ATP, CP and lactate analyses. At the same time periods, blood from a regional vein and vena cava was drawn for pH, pyruvate and lactate analyses. Cellular function was evaluated from repeated measurements of transmembrane potentials. The tourniquet ischemia resulted in a rapid decrease of CP to 40% of the initial level within 1 h and a continuous decrease of ATP. The lactate levels increased continuously. The transmembrane potentials decreased from an initial level of --90 to --54 mV. The release of the tourniquet resulted in a hyperemic reaction and a rapid regain of tissue CP and ATP levels within 5 min of recirculation. There was a continuous washout of lactate up to about 1 h after the release and the transmembrane potentials were normalized after about the same time period. The latter parameters indicate that areas of no-reflow persisted for up to 1 h after restored circulation. The results indicate that after a 3-hour tourniquet ischema, the cellular energy metabolism as well as the membrane function are completely normalized after about 1 h of recirculation.