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Relationship between lipolysis and calcium in epididymal adipose tissue of obese-hyperglycaemic mice

Relationship between lipolysis and calcium in epididymal adipose tissue of obese-hyperglycaemic mice 125 16 16 6 6 J. P. Dehaye J. Winand P. Poloczek J. Christophe Department of Biochemistry, Medical School U. L. B. Brussels Belgium Summary In the epididymal adipose tissue of lean (+/+) C57 BL/6J mice deprived of calcium by ethy-leneglycol-bis-( β -aminoethylether) N,N′-tetraacetic acid (EGTA) treatment, corticotrophin-(1-24)-tetracosapeptide (ACTH)-stimulated lipolysis was abolished and peak levels of adenosine 3′,5′-cyclic monophosphate (cyclic AMP 1 ) were reduced by 80%. Calcium omission was less effective on isoproterenol-stimulated lipolysis and was ineffective on theophylline- or dibutyryl cyclic AMP-stimulated lipolysis. All EGTA effects were reversible. Lipolytic agents stimulated the net uptake of 45 Ca. This effect was inhibited by 2,4-dinitrophenol. The 45 Ca accumulated in response to lipolytic agents was largely La 3+ -nondisplaceable and was released with a half-life of 13 minutes under EGTA treatment. These results suggest that the mechanism promoting 45 Ca uptake in response to lipolytic agents was beyond cyclic AMP production in the adipose tissue of lean mice, but independent of free fatty acid release. In turn, intracellular as well as extracellular calcium facilitated maximal rates of lipolysis. In the adipose tissue of obese-hyperglycaemic (ob/ob) mice, the response to the lipolytic agents of glycerol release and cyclic AMP levels was reduced by 65% and 45 Ca uptake was not stimulated. A 1–2 hour preincubation of adipose tissue increased markedly the effect upon lipolysis and 45 Ca uptake, but not that of peak cyclic AMP levels of isoproterenol. It is concluded that the adipose tissue of ob/ob mice displayed a reversible impairment of 45 Ca uptake in response to lipolytic agents. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Diabetologia Springer Journals

Relationship between lipolysis and calcium in epididymal adipose tissue of obese-hyperglycaemic mice

Diabetologia , Volume 16 (6) – Jun 1, 1979

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References (52)

Publisher
Springer Journals
Copyright
Copyright © 1979 by Springer-Verlag
Subject
Medicine & Public Health; Human Physiology; Internal Medicine; Metabolic Diseases
ISSN
0012-186X
eISSN
1432-0428
DOI
10.1007/BF01223161
Publisher site
See Article on Publisher Site

Abstract

125 16 16 6 6 J. P. Dehaye J. Winand P. Poloczek J. Christophe Department of Biochemistry, Medical School U. L. B. Brussels Belgium Summary In the epididymal adipose tissue of lean (+/+) C57 BL/6J mice deprived of calcium by ethy-leneglycol-bis-( β -aminoethylether) N,N′-tetraacetic acid (EGTA) treatment, corticotrophin-(1-24)-tetracosapeptide (ACTH)-stimulated lipolysis was abolished and peak levels of adenosine 3′,5′-cyclic monophosphate (cyclic AMP 1 ) were reduced by 80%. Calcium omission was less effective on isoproterenol-stimulated lipolysis and was ineffective on theophylline- or dibutyryl cyclic AMP-stimulated lipolysis. All EGTA effects were reversible. Lipolytic agents stimulated the net uptake of 45 Ca. This effect was inhibited by 2,4-dinitrophenol. The 45 Ca accumulated in response to lipolytic agents was largely La 3+ -nondisplaceable and was released with a half-life of 13 minutes under EGTA treatment. These results suggest that the mechanism promoting 45 Ca uptake in response to lipolytic agents was beyond cyclic AMP production in the adipose tissue of lean mice, but independent of free fatty acid release. In turn, intracellular as well as extracellular calcium facilitated maximal rates of lipolysis. In the adipose tissue of obese-hyperglycaemic (ob/ob) mice, the response to the lipolytic agents of glycerol release and cyclic AMP levels was reduced by 65% and 45 Ca uptake was not stimulated. A 1–2 hour preincubation of adipose tissue increased markedly the effect upon lipolysis and 45 Ca uptake, but not that of peak cyclic AMP levels of isoproterenol. It is concluded that the adipose tissue of ob/ob mice displayed a reversible impairment of 45 Ca uptake in response to lipolytic agents.

Journal

DiabetologiaSpringer Journals

Published: Jun 1, 1979

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