Pulsatile and chronic overt hyperglycaemia increased GLUT1 and gp91^PHOX protein expression in aorta.

<p>Western Blot analyses of GLUT1 (A) and gp91^PHOX (B) in aorta homogenates. Representive immunoblots of GLUT1, gp91^PHOX and β-actin are shown above the bars. Data are means ± SEM, n = 7–8. *p < 0.05 vs. VEH, $p < 0.05 vs. SLG.</p

Sustained but not Pulsatile hyperglycaemia increases oxidative stress in liver.

<p>Liver MDA (A), SOD activity (B) and protein expression of gp91^PHOX (C) were determined in liver homogenates. Representive immunoblots of gp91^PHOX and β-actin are shown above the bars. Data are means ± SEM, n = 7–8. *p<0.05, ***p<0.0001 vs. VEH.</p

Pulsatile Hyperglycaemia Induces Vascular Oxidative Stress and GLUT 1 Expression More Potently than Sustained Hyperglycaemia in Rats on High Fat Diet

<div><p>Introduction</p><p>Pulsatile hyperglycaemia resulting in oxidative stress may play an important role in the development of macrovascular complications. We investigated the effects of sustained vs. pulsatile hyperglycaemia in insulin resistant rats on markers of oxidative stress, enzyme expression and glucose metabolism in liver and aorta. We hypothesized that liver’s ability to regulate the glucose homeostasis under varying states of hyperglycaemia may indirectly affect oxidative stress status in aorta despite the amount of glucose challenged with.</p><p>Methods</p><p>Animals were infused with sustained high (SHG), low (SLG), pulsatile (PLG) glucose or saline (VEH) for 96 h. Oxidative stress status and key regulators of glucose metabolism in liver and aorta were investigated.</p><p>Results</p><p>Similar response in plasma lipid oxidation was observed in PLG as in SHG. Likewise, in aorta, PLG and SHG displayed increased expression of glucose transporter 1 (GLUT1), gp-91^PHOX and super oxide dismutase (SOD), while only the PLG group showed increased accumulation of oxidative stress and oxidised low density lipoprotein (oxLDL) in aorta.</p><p>Conclusion</p><p>Pulsatile hyperglycaemia induced relatively higher levels of oxidative stress systemically and in aorta in particular than overt sustained hyperglycaemia thus supporting the clinical observations that pulsatile hyperglycaemia is an independent risk factor for diabetes related macrovascular complications.</p></div

Chronic sustained hyperglycaemia down regulates key glycolytic enzymes in liver.

<p>After 96 hours of different glucose infusion paradigms liver was analysed for glycogen (A) and triglyceride (B) content and the expression level of GK (protein (C); mRNA (D)); GS (protein (E); mRNA (F)); Screbp1c (protein (G); mRNA (H)). Representive immunoblots of GK, GS, Screbp1c and β-actin are shown above the bars. Data are means ± SEM, n = 7–8. *p < 0.05, **p < 0.001 and ***p<0.0001 vs. VEH. $p < 0.05 vs. SLG. £p < 0.05 vs. SHG.</p

Pulsatile hyperglycaemia induced increased oxidative stress status and accumulation of oxLDL in aorta.

<p>Aorta homogenates were analysed for MDA content (A), SOD activity (B) and oxLDL (C) accumulation. Data are means ± SEM, n = 7–8. *p < 0.05 vs. VEH, $p < 0.05 vs. SLG.</p

Pulsatile hyperglycaemia increases systemic oxidative stress status independent of glycemic exposure.

<p>Plasma glucose (A) and insulin (B) was followed throughout the complete study period. The PLG group were subjected to nine glucose pulses daily and the glucose levels were determined at selected time points covering the complete circadian rhythm. Plasma MDA (C) and 8-IsoP (D) was monitored daily at the exact same time point. Data are only means for plasma glucose and insulin and means ± SEM for plasma MDA and 8-IsoP, n = 7–8. *p < 0.05 vs. VEH.</p

Plasma levels of three pro-inflammatory markers and YKL-40.

<p>The time point 0 indicates the administration of <i>E. coli</i> endotoxin (LPS). The endotoxaemia was induced at day time (blue curve) and night time (red curve). Results from the two-way ANOVA: (1) interaction term (time*day) were not significant for any of the markers. (2) between groups analyses were significant for IL-6 (<i>P</i><0.0001) and YKL-40 (<i>P</i><0.001). *) <i>P</i>-value<0.05 calculated by Wilcoxon-Rank test. **) <i>P</i>-value<0.01 calculated by Wilcoxon-Rank test. ***) <i>P</i>-value<0.001 calculated by Wilcoxon-Rank test.</p

Plasma levels of the analysed oxidative markers.

<p>The time point 0 indicates the administration of LPS endotoxin 0.3/kg on 12 healthy men. The endotoxaemia was induced at day time (blue curve) and night time (red curve). Results from the two-way ANOVA: (1) interaction term (time*day) were significant for MDA (<i>P</i><0.05). (2) between groups analyses were significant for MDA (<i>P</i><0.05). *) <i>P</i>-value<0.05 calculated by Wilcoxon-Rank test.</p

Result of two way repeated measures of ANOVA.

<p>ns (not significant).</p><p>IL: ineterleukin.</p><p>TNF: tumor-necrosis factor.</p><p>MDA (malondialdehyde).</p><p>AA (ascorbic acid).</p><p>DHA (Dehydroascorbic acid).</p

Body temperature (A), heart rate (B) and mean blood pressure (C) during endotoxaemia.

<p>The time point 0 indicates the time of LPS administration. Endotoxaemia was induced at day time (blue curve) and night time (red curve). Results from the two-way ANOVA: (1) interaction term (time*day) were not significant, (2) between groups analyses were significant for temperature (<i>P</i><0.0001) and mean blood pressure (<i>P</i><0.001).</p