Reduced capability of transmitting high frequency impulses in tail nerves of diabetic rats

The effect of long‐term (40 min) high frequency stimulation (143 Hz) of sensory‐motor tail nerves was studied in normal and in streptozotocindiabetic rats. The study comprised a 6‐week period, repeating the test at 2‐week intervals. In the initial (prediabetic) study, single experiments showed a mild depression of the peak‐to‐peak ampltiude during high frequency stimulation, which reversed completely during a subsequent rest period. In normal rats, the amplitude depression was unchanged in repeated tests over a 6‐week period. Diabetic rats showed a greater amplitude depression during high frequency stimulation. The difference was statistically significant after 2 weeks, but showed no further change at subsequent tests. The greater decrease in the amplitude in diabetic rats may reflect a depression of the axon membrane function, which may be the functionl correlate to the inhibition of the Na/K ATPase activity in diabetes, described by others. Monitoring of the axon membrane functional capacity may have clinical implications in the control of peripheral neuropathies. © 1993 John Wiley & Sons, Inc.