Effect of gliquidone on insulin binding to rabbit erythrocytes

A study was made of the effects of acute or chronic treatment of rabbits with 10 mg gliquidone (Glurenorm)/kg body weight on erythrocyte insulin receptors. The binding of 125I-labelled insulin to the population of whole red blood cells was not affected by either treatment. Because of the heterogeneity of the erythrocytes, subpopulations were selected according to their specific gravity, which is directly related to cell age. The lowest-density fraction showed a 30% greater capacity of the insulin receptors without any change in affinity after chronic therapy with gliquidone, but no effects were observable after acute treatment. The highest-density fraction was not affected by either acute or chronic administration of gliquidone. Therefore, all other things being equal (blood sugar, plasma insulin levels), young erythrocytes are sensitive to sulphonylurea, whereas old ones are not. Irrespective of the compound tested, this observation suggests that receptor sensitivity might be tissue-specific or age-specific or both, and that the stage of maturation of a cell is a determining factor.