We have investigated changes in insulin binding to erythrocytes in response to the
oral administration of 500 mg of L-Dopa in ten healthy subjects. L-Dopa administration
increases insulin binding from 5.18 ± 0.14% (mean ± SEM) to 6.18 ± 0.34 % (P<0.05)
with concomitant increase in basal plasma growth hormone from 1.3 ± 0.1 ng/ml to 14.4
± 4.8 ng/ml (P<0.05). The increase in insulin binding is due to increase in affinity
of insulin receptor without changes in the number of insulin receptors. The plasma
insulin and glucose did not show significant changes after L-Dopa administration.
Direct incubation of L-Dopa with erythrocytes did not affect insulin binding to the
cells. These results suggest that growth hormone may directly of indirectly induce
acute alteration in affinity of insulin receptors on erythrocytes.
Insulin
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Receptor
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Growth Hormone
