Effect of myo-inositol supplementation on the development of renal pathological changes in the Cohen diabetic (type 2) rat.

A lower concentration of intracellular myo-inositol has been implicated in the development of diabetic nephropathy. This was based on short-term studies showing that early administration of aldose reductase inhibitors or myo-inositol supplementation reduces increased glomerular filtration rate and partly reduces increased urinary albumin excretion in streptozotocin diabetic rats. We studied the effect of long-term (4 months) administration of 1% myo-inositol supplement to the Cohen diabetic (type 2) rat on the development of nephropathy and renal Na(+)-K(+)-ATPase. This treatment reduced the increased renal Na(+)-K(+)-ATPase activity but had no effect on blood glucose levels, body weight, increased kidney weight, or creatinine clearance and did not prevent or reduce the development of renal glomerular pathology. There was no correlation between the level of Na(+)-K(+)-ATPase activity and the degree of nephropathy. It is possible that the renal pathological changes are due to metabolic and humoral factors resulting from hyperglycaemia, other than myo-inositol depletion. The fact that myo-inositol treatment had no effect on the development of renal pathological changes but was shown to have a beneficial effect on restoring impaired conduction velocity and on the disruption of structural elements in the nerve indicates that the effect of the biological changes ensuing from hyperglycaemia vary in different tissues depending on local conditions.