scholarly journals Short-term K+ deprivation provokes insulin resistance of cellular K+ uptake revealed with the K+ clamp

2001 ◽  
Vol 280 (1) ◽  
pp. F95-F102 ◽  
Author(s):  
Cheol S. Choi ◽  
Curtis B. Thompson ◽  
Patrick K. K. Leong ◽  
Alicia A. McDonough ◽  
Jang H. Youn
Keyword(s):  
Insulin Resistance ◽  
Atpase Activity ◽  
Infusion Rate ◽  
Insulin Action ◽  
Insulin Dose ◽  
Short Term ◽  
Conscious Rat ◽  
Physiological Concentration ◽  
Glucose Clearance

We aimed to test the feasibility of quantifying insulin action on cellular K+ uptake in vivo in the conscious rat by measuring the exogenous K+ infusion rate needed to maintain constant plasma K+ concentration ([K+]) during insulin infusion. In this “K+ clamp” the K+ infusion rate required to clamp plasma [K+] is a measure of insulin action to increase net plasma K+ disappearance. K+ infusion rate required to clamp plasma [K+] was insulin dose dependent. Renal K+ excretion was not significantly affected by insulin at a physiological concentration (∼90 μU/ml, P > 0.05), indicating that most of insulin-mediated plasma K+ disappearance was due to K+ uptake by extrarenal tissues. In rats deprived of K+ for 2 days, plasma [K+] fell from 4.2 to 3.8 mM, insulin-mediated plasma glucose clearance was normal, but insulin-mediated plasma K+ disappearance decreased to 20% of control, even though there was no change in muscle Na-K-ATPase activity or expression, which is believed to be the main K+ uptake route. After 10 days K+ deprivation, plasma [K+] fell to 2.9 mM, insulin-mediated K+ disappearance decreased to 6% of control (glucose clearance normal), and there were 50% decreases in Na-K-ATPase activity and α2-subunit levels. In conclusion, the present study proves the feasibility of the K+ clamp technique and demonstrates that short-term K+ deprivation leads to a near complete insulin resistance of cellular K+uptake that precedes changes in muscle sodium pump expression.

scholarly journals Endothelial insulin receptors differentially control insulin signaling kinetics in peripheral tissues and brain of mice

2017 ◽  
Vol 114 (40) ◽  
pp. E8478-E8487 ◽  
Author(s):  
Masahiro Konishi ◽  
Masaji Sakaguchi ◽  
Samuel M. Lockhart ◽  
Weikang Cai ◽  
Mengyao Ella Li ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Endothelial Cells ◽  
Food Intake ◽  
Insulin Signaling ◽  
Insulin Action ◽  
Insulin Receptors ◽  
Brain Regions ◽  
Peripheral Tissues ◽  
Systemic Insulin Resistance

Insulin receptors (IRs) on endothelial cells may have a role in the regulation of transport of circulating insulin to its target tissues; however, how this impacts on insulin action in vivo is unclear. Using mice with endothelial-specific inactivation of the IR gene (EndoIRKO), we find that in response to systemic insulin stimulation, loss of endothelial IRs caused delayed onset of insulin signaling in skeletal muscle, brown fat, hypothalamus, hippocampus, and prefrontal cortex but not in liver or olfactory bulb. At the level of the brain, the delay of insulin signaling was associated with decreased levels of hypothalamic proopiomelanocortin, leading to increased food intake and obesity accompanied with hyperinsulinemia and hyperleptinemia. The loss of endothelial IRs also resulted in a delay in the acute hypoglycemic effect of systemic insulin administration and impaired glucose tolerance. In high-fat diet-treated mice, knockout of the endothelial IRs accelerated development of systemic insulin resistance but not food intake and obesity. Thus, IRs on endothelial cells have an important role in transendothelial insulin delivery in vivo which differentially regulates the kinetics of insulin signaling and insulin action in peripheral target tissues and different brain regions. Loss of this function predisposes animals to systemic insulin resistance, overeating, and obesity.

Disruption of endothelial Pfkfb3 ameliorates diet-induced murine insulin resistance

2021 ◽  
Author(s):  
Qiuhua Yang ◽  
Jiean Xu ◽  
Qian Ma ◽  
Zhiping Liu ◽  
Yaqi Zhou ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Endothelial Cells ◽  
High Fat Diet ◽  
Inflammatory Responses ◽  
Critical Role ◽  
Endothelial Inflammation ◽  
Glucose Clearance ◽  
Deficient Mice

Overnutrition-induced endothelial inflammation plays a crucial role in high fat diet (HFD)-induced insulin resistance in animals. Endothelial glycolysis plays a critical role in endothelial inflammation and proliferation, but its role in diet-induced endothelial inflammation and subsequent insulin resistance has not been elucidated. PFKFB3 is a critical glycolytic regulator, and its increased expression has been observed in adipose vascular endothelium of C57BL/6J mice fed with HFD in vivo, and in palmitate (PA)-treated primary human adipose microvascular endothelial cells (HAMECs) in vitro. We generated mice with Pfkfb3 deficiency selective for endothelial cells to examine the effect of endothelial Pfkfb3 in endothelial inflammation in metabolic organs and in the development of HFD-induced insulin resistance. EC Pfkfb3-deficient mice exhibited mitigated HFD-induced insulin resistance, including decreased body weight and fat mass, improved glucose clearance and insulin sensitivity, and alleviated adiposity and hepatic steatosis. Mechanistically, cultured PFKFB3 knockdown HAMECs showed decreased NF-κB activation induced by PA, and consequent suppressed adhesion molecule expression and monocyte adhesion. Taken together, these results demonstrate that increased endothelial PFKFB3 expression promotes diet-induced inflammatory responses and subsequent insulin resistance, suggesting that endothelial metabolic alteration plays an important role in the development of insulin resistance.

Short-term effect of aldosterone on NEM-sensitive ATPase in rat collecting tubule

1989 ◽  
Vol 257 (2) ◽  
pp. F177-F181 ◽  
Author(s):  
C. Khadouri ◽  
S. Marsy ◽  
C. Barlet-Bas ◽  
A. Doucet
Keyword(s):  
Atpase Activity ◽  
Affinity Constant ◽  
Short Term ◽  
Collecting Tubule ◽  
Lag Period ◽  
In Vitro Effects ◽  
Collecting Tubules

Because previous studies indicated that in the collecting tubule, N-ethylmaleimide (NEM)-sensitive ATPase, the biochemical equivalent of the proton pump, is controlled by mineralocorticoids in the long term, the present study was designed to investigate whether such control also exists in the short term. Therefore we investigated the in vivo and in vitro effects of aldosterone on the enzyme activity in cortical and outer medullary collecting tubules (CCT and MCT, respectively) from adrenalectomized rats. Administration of aldosterone (10 micrograms/kg body wt) markedly stimulated NEM-sensitive ATPase activity in the CCT and MCT within 3 h. Similarly, incubating CCT or MCT for 3 h in the presence of 10(-8) M aldosterone enhanced NEM-sensitive ATPase activity up to values similar to those previously measured in the corresponding nephron segments of normal rats. In vitro stimulation of NEM-sensitive ATPase was dose dependent in regard to aldosterone (apparent affinity constant approximately 10(-9) M), appeared after a 30-min lag period, and reached its maximum after 2-2.5 h. Finally, actinomycin D and cycloheximide totally abolished the in vitro action of aldosterone, demonstrating the involvement of protein synthesis in this process.

Sepsis-induced changes in in vivo insulin action in diabetic rats

1989 ◽  
Vol 257 (3) ◽  
pp. E301-E308 ◽  
Author(s):  
C. H. Lang ◽  
C. Dobrescu
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Insulin Action ◽  
Plasma Concentrations ◽  
Diabetic Rats ◽  
Hepatic Insulin Resistance ◽  
Blood Levels ◽  
Euglycemic Hyperinsulinemic Clamp ◽  
Glucose Output

The present study examined whether sepsis exacerbates the diabetes-induced peripheral and hepatic insulin resistance. Vascular catheters were placed in diabetic (70 mg/kg streptozotocin, 4-wk duration) and nondiabetic rats, and sepsis was produced by subcutaneous injections of live Escherichia coli. Basal glucose metabolism was determined with the use of [3-3H]glucose initiated 18 h after the first injection of bacteria. Thereafter, in vivo insulin action was assessed with the use of the euglycemic hyperinsulinemic clamp technique. Sepsis in nondiabetic rats produced a 57% reduction in the maximal responsiveness for the insulin-induced increase in total glucose utilization compared with nondiabetic nonseptic animals. Diabetes alone decreased both insulin sensitivity and responsiveness. When the septic insult was superimposed on the diabetic condition, the maximum responsiveness was unchanged compared with non-septic diabetic rats, but the 50% maximally efficient dose was reduced from 817 to 190 microU/ml, suggesting an improvement in insulin sensitivity. Sepsis did not alter the insulin-induced suppression of hepatic glucose output in either nondiabetic or diabetic animals. Sepsis increased the plasma concentrations of epinephrine, norepinephrine, glucagon, and corticosterone in both nondiabetic and diabetic rats; however, the elevation in catecholamines and glucagon was 65 to 250% greater in the diabetic animals. These results indicate that hypermetabolic sepsis produces peripheral insulin resistance in nondiabetic rats but does not worsen the preexisting insulin resistance in diabetic animals, despite the higher prevailing blood levels of glucagon and catecholamines.

scholarly journals Short-term infusion of interleukin-6 does not induce insulin resistance in vivo or impair insulin signalling in rats

Diabetologia ◽  
2004 ◽  
Vol 47 (11) ◽  
pp. 1879-1887 ◽  
Author(s):  
V. Rotter Sopasakis ◽  
B.-M. Larsson ◽  
A. Johansson ◽  
A. Holm�ng ◽  
U. Smith
Keyword(s):  
Insulin Resistance ◽  
Interleukin 6 ◽  
Insulin Signalling ◽  
Short Term ◽  
Induce Insulin Resistance

scholarly journals Overexpression of the ped/pea-15 Gene Causes Diabetes by Impairing Glucose-Stimulated Insulin Secretion in Addition to Insulin Action

2004 ◽  
Vol 24 (11) ◽  
pp. 5005-5015 ◽  
Author(s):  
Giovanni Vigliotta ◽  
Claudia Miele ◽  
Stefania Santopietro ◽  
Giuseppe Portella ◽  
Anna Perfetti ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Secretion ◽  
Protein Kinase ◽  
Transgenic Mice ◽  
Insulin Action ◽  
Glucose Levels ◽  
Beta Cell Line ◽  
Protein Kinase Cα ◽  
Glucose Stimulated Insulin Secretion

ABSTRACT Overexpression of the ped/pea-15 gene is a common feature of type 2 diabetes. In the present work, we show that transgenic mice ubiquitously overexpressing ped/pea-15 exhibited mildly elevated random-fed blood glucose levels and decreased glucose tolerance. Treatment with a 60% fat diet led ped/pea-15 transgenic mice to develop diabetes. Consistent with insulin resistance in these mice, insulin administration reduced glucose levels by only 35% after 45 min, compared to 70% in control mice. In vivo, insulin-stimulated glucose uptake was decreased by almost 50% in fat and muscle tissues of the ped/pea-15 transgenic mice, accompanied by protein kinase Cα activation and block of insulin induction of protein kinase Cζ. These changes persisted in isolated adipocytes from the transgenic mice and were rescued by the protein kinase C inhibitor bisindolylmaleimide. In addition to insulin resistance, ped/pea-15 transgenic mice showed a 70% reduction in insulin response to glucose loading. Stable overexpression of ped/pea-15 in the glucose-responsive MIN6 beta-cell line also caused protein kinase Cα activation and a marked decline in glucose-stimulated insulin secretion. Antisense block of endogenous ped/pea-15 increased glucose sensitivity by 2.5-fold in these cells. Thus, in vivo, overexpression of ped/pea-15 may lead to diabetes by impairing insulin secretion in addition to insulin action.

Kupffer cell activation is a causal factor for hepatic insulin resistance

2010 ◽  
Vol 298 (1) ◽  
pp. G107-G116 ◽  
Author(s):  
Nicolas Lanthier ◽  
Olivier Molendi-Coste ◽  
Yves Horsmans ◽  
Nico van Rooijen ◽  
Patrice D. Cani ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Kupffer Cell ◽  
High Fat Diet ◽  
Cell Activation ◽  
Hepatic Insulin Resistance ◽  
High Fat ◽  
Short Term ◽  
Adipose Tissue Macrophages ◽  
Diet Model

Recruited adipose tissue macrophages contribute to chronic and low-grade inflammation causing insulin resistance in obesity. Similarly, we hypothesized here that Kupffer cells, the hepatic resident macrophages, play a pathogenic role in hepatic insulin resistance induced by a high-fat diet. Mice were fed a normal diet or high-fat diet for 3 days. Kupffer cell activation was evaluated by immunohistochemistry and quantitative RT-PCR. Insulin sensitivity was assessed in vivo by hyperinsulinemic-euglycemic clamp and insulin-activated signaling was investigated by Western blot. Liposome-encapsulated clodronate was injected intravenously to deplete macrophages prior to a short-term exposure to high-fat diet. Here, we characterized a short-term high-fat diet model in mice and demonstrated early hepatic insulin resistance and steatosis concurrent with Kupffer cell activation. We demonstrated that selective Kupffer cell depletion obtained by intravenous clodronate, without affecting adipose tissue macrophages, was sufficient to enhance insulin-dependent insulin signaling and significantly improve hepatic insulin sensitivity in vivo in this short-term high-fat diet model. Our study clearly shows that hepatic macrophage response participates to the onset of high-fat diet-induced hepatic insulin resistance and may therefore represent an attractive target for prevention and treatment of diet- and obesity-induced insulin resistance.

Temporal changes in insulin resistance and secretion in 24-h-fasted conscious pregnant rats

1993 ◽  
Vol 265 (6) ◽  
pp. E845-E851 ◽  
Author(s):  
G. Rossi ◽  
R. S. Sherwin ◽  
A. S. Penzias ◽  
P. Lapaczewski ◽  
R. J. Jacob ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Action ◽  
Insulin Dose ◽  
Glucose Production ◽  
Late Pregnancy ◽  
Hepatic Insulin Resistance ◽  
Pregnant Rats ◽  
Hyperglycemic Clamp ◽  
Peripheral Insulin Resistance ◽  
Insulin Responses

To determine the temporal sequence of pregnancy-induced changes in insulin action and secretion, awake midpregnant (11-12 days) and late pregnant (19-20 days) rats underwent a two-step euglycemic hyperinsulinemic or a hyperglycemic clamp study after a 24-h fast. During euglycemia, insulin-stimulated increments in glucose uptake and clearance in midpregnant rats were reduced by 60-70% at the lower dose (insulin approximately 360 pM) and by 20-30% at the higher dose (insulin approximately 1,750 pM; P < 0.01 vs. virgin controls). Insulin action was also diminished in late pregnant rats. However, the magnitude of resistance did not increase. Insulin-mediated suppression of glucose production was only minimally impaired in midpregnancy. In contrast, glucose production was virtually unchanged in late pregnancy, even at the highest insulin dose. During hyperglycemia, insulin responses in late pregnancy were markedly increased 5-fold above controls and 2.5-fold above midpregnant rats (P < 0.05). We conclude that rat pregnancy is characterized by the early appearance of peripheral insulin resistance. As pregnancy progresses toward term, marked hepatic insulin resistance and insulin hypersecretion develop, whereas peripheral insulin resistance demonstrates negligible changes. These data imply that insulin hypersecretion during late pregnancy is most closely linked to hepatic insulin resistance, at least in 24-h-fasted animals.

In vivo insulin action in genetic models of hypertension

1992 ◽  
Vol 262 (2) ◽  
pp. E191-E196 ◽  
Author(s):  
S. Frontoni ◽  
L. Ohman ◽  
J. R. Haywood ◽  
R. A. DeFronzo ◽  
L. Rossetti
Keyword(s):  
Insulin Resistance ◽  
Blood Pressure ◽  
Glucose Uptake ◽  
Insulin Action ◽  
Hepatic Glucose Production ◽  
High Dose ◽  
Rat Models ◽  
Genetic Hypertension ◽  
Per Se

Insulin resistance has been described in nonobese subjects with essential hypertension. At present it is unknown whether hypertension per se may lead to the onset of insulin resistance. To examine this question we studied in vivo insulin action in two rat models of genetic hypertension. Four groups of conscious rats were studied: Milan hypertensive (MHS), Milan normotensive (MNS), spontaneously hypertensive (SHR), and Wistar-Kyoto (WKY). Mean arterial pressure was increased in SHR vs. WKY in both the fed (184 +/- 5 vs. 126 +/- 6 mmHg; P less than 0.001) and fasting (160 +/- 5 vs. 129 +/- 5; P less than 0.001) states. During high-dose insulin clamps, total body glucose uptake (mg.kg-1.min-1) was similar in MNS (28.7 +/- 1.4) vs. MHS (33.6 +/- 3.0) and in WKY (34.6 +/- 1.8) vs. SHR (35.7 +/- 2.4). During low-dose insulin clamps, suppression of hepatic glucose production (3.5 +/- 0.6 vs. 3.0 +/- 0.5 mg.kg-1.min-1) and stimulation of glycolysis (12.9 +/- 0.8 vs. 14.4 +/- 1.5 mg.kg-1.min-1) were similar in WKY vs. SHR, whereas glucose uptake (24.6 +/- 1.9 vs. 18.3 +/- 1.2 mg.kg-1.min-1; P less than 0.01) and muscle glycogenic rate (10.2 +/- 1.1 vs. 6.5 +/- 1.1 mg.kg-1.min-1; P less than 0.05) were increased in SHR vs. WKY. In conclusion, 1) feeding markedly augments blood pressure in hypertensive but not in normotensive rats, and 2) hepatic and muscle insulin sensitivity are normal or increased in two different rat models of genetic hypertension. These results provide evidence that high blood pressure per se does not invariably lead to the development of insulin resistance.

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