Opposite effects of diabetes and galactosaemia on adenosine triphosphatase activity in rat nervous tissue

Abstract

This study measured the ouabain-sensitive adenosine triphosphatase activity in sciatic nerve, lumbar dorsal root ganglia and superior cervical ganglia from control rats, rats with 8 weeks streptozotocin-induced diabetes and rats fed a diet containing 20% galactose for 8 weeks. Whilst the sciatic nerves of the diabetic rats showed a 42% reduction in ouabain-sensitive adenosine triphosphatase activity, the galactose-fed rats showed an increase of 124% (p less than 0.01 and p less than 0.005, respectively, compared to controls). There was also a reduction (by 30% compared to controls; p less than 0.05) in the ouabain-sensitive adenosine triphosphatase activity of the dorsal root ganglia from the diabetic rats, but their superior cervical ganglia did not show a significant fall. The ganglia of the galactosaemic rats showed no change in ouabain-sensitive adenosine triphosphatase activity compared to controls. These changes coexisted with increases in appropriate polyol pathway metabolites in all tissues of both diabetic and galactosaemic rats. There were also depletions of myo-inositol in the sciatic nerves and dorsal root ganglia of diabetic and galactosaemic rats, but their superior cervical ganglia contained levels of myo-inositol which were similar to those of controls. The nerves of the galactosaemic rats showed increased water content; the nerves of the diabetic rats did not. The data argue against a simple relationship between myo-inositol depletion and impaired Na/K adenosine triphosphatase activity in association with exaggerated polyol pathway flux in peripheral nervous tissue.