Glucose transporter protein responses to selective hyperglycemia or hyperinsulinemia in fetal sheep
1 Division of Neonatology, Department of Pediatrics, University of Colorado, Denver, Colorado 80262; 2 Division of Neonatology and Developmental Biology, Department of Pediatrics, University of Pittsburgh, Magee Womens Research Institute, Pittsburgh, Pennsylvania 15213; and 3 Division of Neonatol...
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Published in | American journal of physiology. Regulatory, integrative and comparative physiology Vol. 281; no. 5; pp. 1545 - R1552 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
01.11.2001
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Subjects | |
Online Access | Get full text |
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Summary: | 1 Division of Neonatology, Department of Pediatrics,
University of Colorado, Denver, Colorado 80262; 2 Division of
Neonatology and Developmental Biology, Department of Pediatrics,
University of Pittsburgh, Magee Womens Research Institute, Pittsburgh,
Pennsylvania 15213; and 3 Division of Neonatology and
Developmental Biology, Department of Pediatrics, University of
California Los Angeles School of Medicine, Los Angeles, California
90095 - 1752
The acute effect of selective
hyperglycemia or hyperinsulinemia on late gestation fetal ovine glucose
transporter protein (GLUT-1, GLUT-3, and GLUT-4) concentrations was
examined in insulin-insensitive (brain and liver) and insulin-sensitive
(myocardium and fat) tissues at 1, 2.5, and 24 h. Hyperglycemia
with euinsulinemia caused a two- to threefold increase in brain GLUT-3,
liver GLUT-1, and myocardial GLUT-1 concentrations only at 1 h.
There was no change in GLUT-4 protein amounts at any time during the
selective hyperglycemia. In contrast, selective hyperinsulinemia
with euglycemia led to an immediate and persistent twofold increase in
liver GLUT-1, which lasted from 1 until 24 h with a concomitant
decline in myocardial tissue GLUT-4 amounts, reaching statistical
significance at 24 h. No other significant change in response to
hyperinsulinemia was noted in any of the other isoforms in any of the
other tissues. Simultaneous assessment of total fetal glucose
utilization rate (GUR f ) during selective hyperglycemia
demonstrated a transient 40% increase at 1 and 2.5 h,
corresponding temporally with a transient increase in brain GLUT-3 and
liver and myocardial GLUT-1 protein amounts. In contrast, selective
hyperinsulinemia led to a sustained increase in GUR f ,
corresponding temporally with the persistent increase in hepatic GLUT-1
concentrations. We conclude that excess substrate acutely increases
GUR f associated with an increase in various tissues of the
transporter isoforms GLUT-1 and GLUT-3 that mediate fetal basal glucose
transport without an effect on the GLUT-4 isoform that mediates insulin
action. This contrasts with the tissue-specific effects of selective
hyperinsulinemia with a sustained increase in GUR f
associated with a sustained increase in hepatic basal glucose
transporter (GLUT-1) amounts and a myocardial-specific emergence of
mild insulin resistance associated with a downregulation of GLUT-4.
development; brain; myocardium; adipose tissue; liver |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0363-6119 1522-1490 |
DOI: | 10.1152/ajpregu.2001.281.5.r1545 |