Abstract
To determine whether erythrocytes behave like other insulin target cells such as adipocytes in regard to their insulin binding, we studied the insulin binding of erythrocytes and adipocytes rom the same rat.
In order to test affinity changes of the insulin recepors, we used 48-hour fasted rats, and for changes in insulin receptor number, we compared the insulin binding of lean young rats and old obese rats.
With 48 hours fasting, the affinity of the insulin receptors increased in both erythrocytes and adipocytes from lean rats. However, in obese rats, there were no significant changes in the affinity of the receptors in both erythrocytes and adipocytes from fasted rats.
As for changes in the receptor number, a 50% decrease in insulin receptor number was noted in both erythrocytes and adipocytes from obese rats.
A close relationship existed between the insulin binding at an insulin concentration of 0.2 ng/ml and the plasma insulin levels both in erythrocytes (r=-0.556, p<0.05) and adipocytes (r=-0.503, p<0.05). Furthermore, there was a close relationship in insulin binding between erythrocytes and adipocytes (r=0.685, p<0.01).
It is apparent from the above results that rat erythrocyte insulin receptors mirror changes in the insulin receptors of other insulin target cells such as adipocytes.
