Adaptive Regulation of β-Adrenergic Receptors in Children with Insulin Dependent Diabetes Mellitus

Summary

The β-adrenergic receptors were investigated in partially purified mononucleal leukocytes (MNL) plasma membranes from 18 patients with IDDM in pediatric period, 9 healthy children and 8 normal adults. The decreased β-adrenergic receptor number was seen in patients with IDDM (Bmax = 27.6±8.3 fM (125l) IHYP/mg protein) compared with normal children (Bmax = 40.4±10.4 fM (1251) IHYP/mg protein) and normal adults (Bmax = 36.9±6 f M (1251) IHYP/mg protein). MNL β-receptor binding affinities (apparent Kd = 109.8±26.1 pM in IDDM, 102.8±46.6 pM in normal children, 130.0±43.1 pM in normal adults) did not differ. We divided the patients with IDDM into two groups based on their level of blood glycosylated hemoglobin (HbA1) when samples were taken. Group A IDDM (consisted of 9 diabetic patients with below 10% of HbA1) had markedly decreased β-receptor numbers compared with group B IDDM (consisted of 9 diabetic patients with more than 10% of HbA1), whereas Kd was not significantly different. Also, there was negative correlation between Bmax and level of blood sugar or HbA1 in IDDM. This is the first report concerning the β-adrenergic receptor in IDDM in pediatric period. We suggest that decreased Bmax in group B is a homeostatic response to restore the poorly-controlled hyperglycemic state to normoglycemia because the group B patients had high level of HbA1 and blood sugar.

Key-Words

Insulin Dependent Diabetes Mellitus - Catecholamine - Glycosylated Hemoglobin - β-Adrenergic Receptor