Enhancement of glucose uptake in stunned myocardium: role of
glucose transporter.
Hashimoto, Katsuji, Tsunehiko Nishimura, Makoto Ishikawa, Keiko Koga,
Toyoki Mori, Shinichi Matsuda, Masatsugu Hori, and Hideo Kusuoka.
Division of Tracer Kinetics, Biomedical Research Center, and The
First Department of Medicine(3), Osaka University Medical School,
Suita Osaka 565, Bioenergetics Research Center, Tokushima Research
Institute, and The Second Tokushima Institute of New Drug Research,
Otsuka Pharmaceutical Co., Ltd., Tokushima 771-01 JAPAN
APStracts 3:0424H, 1996.
This study quantifies the myocardial glucose uptake and clarifies the
pathway of augmented glucose uptake in myocardium reperfused after a
brief period of ischemia (stunned myocardium). Glucose uptake rate
was determined from the time course of the sugar phosphate resonance
in rat myocardium (d[SP]/dt) using 31P-NMR after substitution of
glucose by its analogue, 2-deoxyglucose. d[SP]/dt in stunned
myocardium (1.03 +/- 0.05 [mu]mol/g wet wt/min [mean +/- SE], N=8)
increased significantly compared with non-ischemic control (0.18 +/-
0.03, N=8, P<0.0001), reaching the maximal stimulable uptake
rate during exposure to insulin (1.05 +/- 0.04, N=8). 20 minutes
after the reperfusion, d[SP]/dt was still augmented (0.41 +/- 0.05,
N=5, P<0.05 vs. control). To elucidate further the mechanism
of augmented glucose uptake, N6-(L-2-phenylisopropyl)adenosine (PIA,
100 [mu]mol/L), a potent blocker of glucose transporter, was
administered to stunned hearts and, as a control, to insulin
-stimulated hearts. PIA significantly and comparably inhibited the
increase in d[SP]/dt in stunned myocardium (0.36 +/- 0.07, N=4,
P<0.0001 vs. PIA(-)) and in insulin-stimulated myocardium
(0.38 +/- 0.02, N=4, P<0.0001 vs. PIA(-)). These results
indicate that the augmented glucose uptake in stunned myocardium is
maintained by glucose transporter, the amount of which is almost
equal to that which can be maximally recruited by insulin.
Received 12 April 1996; accepted in final form 24 September 1996.
APS Manuscript Number H324-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996