Diabetes, Vol 39, Issue 1 62-69, Copyright © 1990 by American Diabetes Association
Adenosine reversal of in vivo hepatic responsiveness to insulin
MP McLane, PR Black, WR Law and RM Raymond
Department of Surgery, Loyola University Stritch School of Medicine, Maywood, Illinois.
Modulation by adenosine of hepatic responsiveness to insulin was
investigated in vivo in 10 healthy mongrel dogs of both sexes by
determining net hepatic glucose output (NHGO) in response to insulin during
the presence or absence of exogenous adenosine infusion. In addition, two
separate series of experiments were performed to study the effect of
adenosine (n = 7) or glucagon (n = 5) on NHGO. Basal NHGO, quantitated via
the Fick principle, was significantly decreased by insulin infusion (4
U/min; 4.8 +/- 0.6 vs. -1.7 +/- 2.6 mg.kg-1.min-1, P less than 0.05). The
addition of an intrahepatic arterial infusion of adenosine (10 mumol/min)
during insulin infusion caused glucose output to return to basal levels
(insulin, -1.7 +/- 2.6 mg.kg-1.min-1; insulin + adenosine, 3.8 +/- 1.6
mg.kg-1.min-1, P less than 0.05). The addition of intrahepatic arterial
saline (control) during insulin infusion had no effect on insulin's action
(insulin, -1.0 +/- 1.9 mg.kg-1.min-1; insulin + saline, -1.2 +/- 1.6
mg.kg-1.min-1, P greater than 0.05). Hepatic glucose, lactate, and oxygen
deliveries were not affected during either insulin or insulin plus
adenosine infusion. Intrahepatic arterial infusion of adenosine alone had
no effect on NHGO, whereas intrahepatic arterial infusion of glucagon alone
stimulated glucose output approximately fivefold (basal, 2.7 +/- 0.4
mg.kg-1.min-1; glucagon, 15.5 +/- 1.2 mg.kg-1.min-1, P less than 0.01).
These results show that adenosine completely reversed the inhibition by
insulin of NHGO. These data suggest that adenosine may act as a modulator
of insulin action on the liver.