Metabolic responses in feline “red” and “white” skeletal muscle to shock and ischemia

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Abstract
Cats were subjected to 2 h of hemorrhagic shock or hind limb tourniquet ischemia and the hypoxia induced changes were studied in the soleus and lateral gastrocnemius muscles to compare hypoxic red and white skeletal muscle. Muscle biopsies were analyzed for ATP, CP [creatine phosphate], glucose, G-6-P and lactate. Using microelectrodes the resting membrane potential was repeatedly measured. Both experimental models cooked in increased tissue lactate levels and a successive decrease in the membrane potential of both muscles studied. No reduction of the high energy phosphagen content (ATP + CP) occurred in any of the muscles during shock. The tourniquet ischemia caused a 40% reduction of the ATP + CP content in the soleus muscle but in the gastrocnemius muscle no significant reduction occurred. The tissue lactate content and the membrane potential under both conditions and in both muscles studied significantly correlated. Apparently red muscles are more susceptible to metabolic derangement than white muscles during total ischemia but during hypovolemia red muscles appear to be protected from early hypoxic damage probably due to a redistribution of skeletal muscle blood flow.