Diabetes, Vol 37, Issue 9 1181-1187, Copyright © 1988 by American Diabetes Association
Deficiency of cardiac beta-adrenergic receptor in streptozocin-induced diabetic rats
Y Nishio, A Kashiwagi, Y Kida, M Kodama, N Abe, Y Saeki and Y Shigeta
Third Department of Medcine, Shiga University of Medical Science, Japan.
The number of beta-adrenergic receptors in cardiac myocytes isolated from
rats made diabetic with streptozocin (STZ) for 10 wk was measured by use of
a hydrophilic nonselective antagonist [3H]CGP 12177 and was found to
decrease to 59% of the number in control rats (P less than .05), without
any change in affinity. Similarly, using [125I]iodocyanopindolol as a
ligand, we found a decrease in the beta-adrenergic-receptor number on
cardiac plasma membrane isolated from the diabetic rats [29% decrease (P
less than .05) at 1 wk, 50% (P less than .01) at 3 wk, and 49% (P less than
.01) at 10 wk compared with control rats]. However, the serum
triiodothyronine level that had been known to modulate the
beta-adrenergic-receptor-adenylate cyclase system was decreased in the
1-wk-diabetic rats but not in the 10-wk-diabetic rats compared with each
control group. Furthermore, there was no difference in urinary
catecholamine excretion between diabetic and control groups. In the
10-wk-diabetic rats, the response of adenylate cyclase to isoproterenol was
significantly defective (56% decrease compared with control rats; P less
than .05), although both the basal and the forskolin-stimulated maximum
adenylate cyclase activities and a half-maximum concentration of
isoproterenol for the stimulation of adenylate cyclase were similar in
control and diabetic rats. On the other hand, both cholera toxin-dependent
and islet-activating protein-dependent [32P]NAD incorporations into cardiac
plasma membrane were markedly increased in the diabetic rats.(ABSTRACT
TRUNCATED AT 250 WORDS)