Predictability of Dielectric Properties for Ischemic Injury of the Skeletal Muscle Before Reperfusion

Objective: The purpose of this study is to assess whether or not dielectric properties could predict the severity of ischemic injury of the skeletal muscle before reperfusion to prevent the myonephropathic metabolic syndrome (MNMS).

Methods: Japanese White rabbits were anesthetized and their hind limbs were subjected to 0, 2, 4, and 6 h of ischemia and then 10 h of reperfusion (n = 4, 5, 6, and 6). Dielectric properties of the gastrocnemius muscle were measured and tan delta(m) and D were calculated from them. To assess ischemic injury, we also measured (a) creatine phosphate kinase (CPK) and aldolase, (b) spectrophotometric assay of triphenyltetrazolium chloride assay, and (c) histological evaluation by H & E staining, 10 h after reperfusion.

Results: The tan delta(m) increased and D decreased significantly compared with those in preischemia (P < 0.01). The tan delta(m) value just before reperfusion significantly correlated positively with the maximum value of CPK (CPK(max)) or the maximum value of aldolase (ALD(max)) (r = 0.73, 0.69) and negatively with %TTC (r = 0.66). The D value just prior to reperfusion significantly correlated negatively with CPK(max) and ALD(max) (r = 0.81, 0.86) and positively with %TTC (r = 0.79) after reperfusion, respectively. Histologically, skeletal muscle necrosis was detected in 11 out of 12 skeletal muscles with tan delta(m) values which were 3.70 or more and 11 out of 14 muscles with D values which were 1.47 or less.

Conclusion: The severity of skeletal muscle ischemic injury can be evaluated before reperfusion by measuring the dielectric properties during ischemia.