Diabetes, Vol 39, Issue 6 663-666, Copyright © 1990 by American Diabetes Association
Coexistence of nerve conduction deficit with increased Na(+)-K(+)-ATPase activity in galactose-fed mice. Implications for polyol pathway and diabetic neuropathy
NA Calcutt, DR Tomlinson and S Biswas
Department of Pharmacology, St. Bartholomew's Hospital Medical College, London, United Kingdom.
We measured motor nerve conduction velocity (MNCV), Na(+)-K(+)-ATPase
activity, polyol-pathway metabolites, and myo-inositol in sciatic nerves
from control mice, galactose-fed (20% wt/wt diet) mice, and galactose-fed
mice given the aldose reductase inhibitor ponalrestat (300-mg/kg diet).
Treatments were maintained for 4 wk. Galactose feeding was associated with
a 21.5% reduction in MNCV (P less than 0.001), which was almost completely
prevented by ponalrestat. Galactose-fed mice showed an 81% increase in
Na(+)-K(+)-ATPase (P less than 0.01), an effect completely prevented by
aldose reductase inhibition. Treatment of a separate galactose-fed group
with sorbinil (300 mg/kg diet) also attenuated the MNCV deficit and
prevented the increased Na(+)-K(+)-ATPase activity associated with
galactosemia. Accumulation of galactitol in the nerves of galactose-fed
mice was prevented by aldose reductase inhibition, but there were no
alterations in myo-inositol levels in the sciatic nerves of any group.
These data show that exaggerated flux through the polyol pathway can cause
an MNCV deficit that is unrelated to either myo-inositol levels or
NA(+)-K(+)-ATPase activity.