Short‐term regulation of glycolysis by insulin and dexamethasone in cultured rat hepatocytes
TLDR
The stimulation of glycolysis by insulin was investigated in monolayer cultures of adult rat hepatocytes and dexamethasone acted both as a long-term and short-term modulator, and the stimulatory effects of insulin may in part be attributed to the activated pyruvate kinase.Abstract:
Evidence for a direct metabolic effect of insulin in isolated liver preparations is scarce. The stimulation of glycolysis by insulin previously demonstrated in monolayer cultures of adult rat hepatocytes [(1982) Eur. J. Biochem. 126, 271-278] was further investigated. The degree of stimulation varied with the age of the culture and amounted to 250%, 200%, 500% and 200% of the control value using cells at the culture age of 2 h, 24 h, 48 h, and 72 h, respectively. Half-maximal dose of insulin was 0.1 nM. Maximal stimulation was reached within 5 min and lasted for at least 4 h. Dexamethasone acted both as a long-term and short-term modulator. Long-term pretreatment of the cells with dexamethasone proved necessary to permit insulin action. In addition to this permissive action, pretreatment with dexamethasone reduced the insulin-independent basal glycolytic rate. In short-term experiments dexamethasone decreased the basal glycolytic flux, however, it did not affect the absolute increase in glycolysis brought about by insulin. The half-maximal dose of dexamethasone was 10 nM. The stimulatory effects of insulin may in part be attributed to the activation of pyruvate kinase. Insulin produced a left-shift of the substrate saturation curve, decreasing the K0.5 value for phosphoenolpyruvate.read more
Citations
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Mechanisms of hormonal regulation of hepatic glucose metabolism
TL;DR: The sympathetic nervous system and its neurohumoral agonists epinephrine and norepinephrine rapidly alter hepatic glycogen metabolism and gluconeogenesis acting through alpha 1-adrenergic receptors and Tyrosine amino-transferase, serine dehydratase, tryptophan oxygenase, and glucokinase are regulated by cAMP.
Journal ArticleDOI
Metabolic zonation of liver parenchyma: significance for the regulation of glycogen metabolism, gluconeogenesis, and glycolysis.
Journal ArticleDOI
Regulation of peripheral insulin/glucagon levels by rat liver
TL;DR: The results indicate that the liver has an important role in the regulation of peripheral insulin/glucagon levels and this role was not constant, but independently regulated.
Journal ArticleDOI
Time courses of changes in hepatic and skeletal muscle insulin action and GLUT4 protein in skeletal muscle after STZ injection
TL;DR: The data indicate that there is a temporal hierarchy in the development of insulin resistance in STZ-induced diabetes, andulin resistance in skeletal muscle appears last (between days 3 and 7 after STZ administration), and the resistance in muscle cannot be fully accounted for by reduced GLUT4 expression.
Journal ArticleDOI
Glucocorticoids fail to cause insulin resistance in human subcutaneous adipose tissue in vivo.
Jonathan Hazlehurst,Laura Gathercole,Maryam Nasiri,Matthew J. Armstrong,Sarah Borrows,Jinglei Yu,Anton J. M. Wagenmakers,Paul M. Stewart,Jeremy W. Tomlinson +8 more
TL;DR: This study represents the first description of sc adipose insulin sensitization by glucocorticoids in vivo and demonstrates tissue-specific actions of glucocortsicoids to modify insulin action, an important advance in the understanding of the actions of both endogenous and exogenous glucoc Corticoids.
References
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Metabolism of isolated fat cells. i. effects of hormones on glucose metabolism and lipolysis.
The Metabolism of Isolated Fat Cells: I. Effects of Hormones on Glucose Metabolism and Lipolysis
TL;DR: This article marks the beginning of Rodbell's interest in cell receptors and related his discovery that fat cells could be isolated from other cells by treating them with preparations of collagenase, and also found that insulin could stimulate glucose uptake.
Journal ArticleDOI
Preparation of rat liver cells. 3. Enzymatic requirements for tissue dispersion.
TL;DR: Isolated perfused rat livers were dispersed by a two-step procedure of Ca2+ removal (probably including the removal of a Ca2-dependent adhesion factor) followed by enzymatic treatment, and cells were active in the synthesis of RNA, protein, glycogen and various metabolites, and showed sensitivity towards steroid and polypeptide hormones.
Journal ArticleDOI
Functional Hepatocellular Heterogeneity
Kurt Jungermann,Norbert Katz +1 more
TL;DR: Hepatocytes from the periportal and perivenous zones of the liver parenchyma differ in their enzyme content and subcellular structures, andeterogeneity in the synthesis of plasma proteins also appears to exist.
Book
Molecular Basis of Insulin Action
TL;DR: The material presented in this volume is, at publication, contemporary with the current original literature, and provides an ex cellent framework for assessing new discoveries in this field for some time to come.
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Jose F. Caro,John M. Amatruda +1 more