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Updated: Aug 15, 2026

Methods for the Determination of Rates of Glucose and Fatty Acid Oxidation in the Isolated Working Rat Heart
Published on: September 28, 2016
Adenosine and insulin mediate glucose uptake in normoxic rat hearts by different mechanisms
D A Angello1, R M Berne, N M Coddington
1Department of Physiology, University of Virginia Health Sciences Center, Charlottesville 22908.
Abstract:
The effect of adenosine (ADO) and its interaction with insulin (I) on myocardial glucose uptake was evaluated in the normoxic isolated rat heart using 2-[3H]deoxyglucose. Isovolumic hearts were perfused at constant flow with a nonrecirculating bicarbonate buffer containing 5.5 mM glucose as the sole substrate. After a 30-min equilibration period, the glucose and extracellular ([14C]sucrose) tracers were infused for 15 min before initiation of the 15-min experimental period. Both 100 microM ADO and 4 mU/ml I significantly increased glucose uptake (GU) compared with control values (in mumol.min-1 x g-1: ADO = 0.34 +/- 0.03, I = 0.44 +/- 0.03, control = 0.23 +/- 0.02; P < 0.05). In combination, ADO and I produced an additive increase in GU (0.54 +/- 0.03; P < 0.05 vs. control). The mechanism of enhanced GU by ADO and I was investigated with the glucose uptake inhibitors phloridzin (PZ) and phloretin (PT), each of which has a unique site of action on the cell membrane. ADO-mediated GU was completely blocked by 3 mM PZ (ADO + PZ = 0.20 +/- 0.01; P = NS vs. control), but I-stimulated GU was unaffected (I + PZ = 0.38 +/- 0.03; P = NS vs. I). Only GU attributable to ADO was blocked by PZ infused with ADO and I (ADO + I + PZ = 0.43 +/- 0.03; P = NS vs. I). Both ADO- and I-mediated GU were inhibited by 100 microM PT.(ABSTRACT TRUNCATED AT 250 WORDS)
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