| 1. |
- Fugmann, Andreas, et al.
(författare)
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Blood flow is an important determinant of forearm glucose uptake following a mixed meal
- 2003
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Ingår i: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 40:3, s. 113-117
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Tidskriftsartikel (refereegranskat)abstract
- Insulin-mediated vasodilation has been suggested to be of importance for glucose uptake during normoglycemic hyperinsulinemia. If this also is valid after an ordinary mixed meal remains to be evaluated. Forearm blood flow (FBF) and forearm glucose uptake change (evaluated by venous occlusion plethysmography) and glucose arteriovenous differences were evaluated over 120 minutes in 10 healthy volunteers following an ordinary mixed meal (700-900 kcal, 34% of energy from fat). Fasting arterial glucose level was 4.9+/-0.9 mmol/l, and the maximum glucose level was reached 30 minutes after the start of ingestion (6.6+/-0.8 mmol/l, p<0.0001). Plasma insulin levels were increased four-fold. FBF increased rapidly within 20 minutes after the start of ingestion and reached its maximum after 50 minutes (94% higher than baseline level, p<0.01). After 2 hours FBF was still substantially elevated (75% above baseline level, p<0.01). Forearm glucose uptake increased fivefold already after 20 minutes ( p<0.01). During the 2 hours, the increase in FBF contributed to 41% of the forearm glucose uptake ( p<0.05). The present study showed that the increase in FBF seen after an ordinary mixed meal is important for the change in forearm glucose uptake. These results support the view that modulation of limb blood flow is a determinant of glucose uptake.
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| 2. |
- Fugmann, Andreas, et al.
(författare)
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Central and peripheral haemodynamic effects of hyperglycaemia, hyperinsulinaemia, hyperlipidaemia or a mixed meal
- 2003
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 105:6, s. 715-721
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to evaluate the haemodynamic changes during hyperinsulinaemia, hyperglycaemia or hypertriglyceridaemia in relation to those following a mixed meal. Ten subjects were subjected to hypertriglyceridaemia (3.9 mmol/l) for 2 h by an infusion of Intralipid and heparin. Nine subjects received a hyperglycaemic clamp (12.5 mmol/l) with octreotide and low-dose insulin infusion to maintain normoinsulinaemia (10 m-units/l). Ten subjects received saline for 2 h as a control and, thereafter, 2 h of normoglycaemic hyperinsulinaemic clamp (80 m-units/l). Finally, ten subjects were evaluated for 2 h following an ordinary mixed meal. Calf blood flow was measured by venous occlusion plethysmography and cardiac index by thoracic bioimpedance. Both the mixed meal and normoglycaemic hyperinsulinaemia lowered total peripheral resistance, and increased calf blood flow and cardiac index, whereas blood pressure decreased (P <0.05-0.001). Both hyperglycaemia and hypertriglyceridaemia increased calf blood flow, but blood pressure was unchanged. Total peripheral resistance was unchanged in hypertriglyceridaemia, whereas hyperglycaemia induced a significant increase. Normoglycaemic hyperinsulinaemia induced a haemodynamic pattern similar, but to a lesser extent, to the pattern seen following a mixed meal. Hyperinsulinaemia seems to be a major mediator of the haemodynamic response, but other factors are obviously also of great importance. Hypertriglyceridaemia and hyperglycaemia induced haemodynamic responses that are not similar to those seen following a mixed meal.
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| 3. |
- Lind, Lars, et al.
(författare)
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Ageing impairs insulin-mediated vasodilatation but not forearm glucose uptake
- 2001
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 31:10, s. 860-864
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It is unclear if insulin-mediated vasodilatation is altered by ageing and if this affects insulin-mediated glucose uptake. MATERIAL AND METHODS: A 2-h euglycaemic hyperinsulinaemic clamp (56 mU m(-2) min(-1)) was performed in 10 healthy, nonobese elderly men (70-75 years) and 13 young men (23-28 years). Forearm blood flow (FBF) was measured by venous occlusion plethysmography and forearm glucose uptake was calculated by arterial and venous serum glucose determinations in the forearm. RESULTS: Insulin induced an increase in FBF in the younger men (from 3.9 +/- 1.1 SD to 5.9 +/- 2.2 mL min(-1) 100(-1)mL tissue, P < 0.001), but this insulin-mediated vasodilatation was completely blunted in the elderly subjects. Glucose extraction during the clamp was significantly higher in the elderly subjects (1.2 +/- 0.76 vs. 0.82 +/- 0.37 mmol L(-1) at 120 min, P < 0.01), resulting in a similar forearm glucose uptake in the two groups. On the other hand, whole-body glucose uptake was significantly decreased in the elderly subjects (5.3 +/- 1.8 vs. 8.0 +/- 1.1 mg kg(-1) min(-1), P < 0.001). CONCLUSION: The present study showed that the ability of insulin to induce vasodilatation is blunted in the forearm in healthy, nonobese elderly subjects. However, the elderly compensate for this impairment with an increased glucose extraction from arterial blood to maintain an unaltered forearm glucose uptake.
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| 4. |
- Lind, Lars, et al.
(författare)
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Insulin-mediated vasodilatation, but not glucose uptake or endothelium-mediated vasodilatation, is enhanced in young females compared with males
- 2002
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 102:2, s. 241-246
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Tidskriftsartikel (refereegranskat)abstract
- In order to evaluate possible differences between men and women with regard to the ability of insulin to induce vasodilatation, promote glucose uptake and enhance endothelium-dependent vasodilatation, 12 young (22-28 years), non-obese women and 15 corresponding males were subjected to 2 h of euglycaemic hyperinsulinaemia (insulin infusion rate of 56 m-units x min(-1) x m(-2)). Forearm blood flow was measured by venous occlusion plethysmography. Endothelium-dependent vasodilatation was evaluated by the local intra-arterial infusion of methacholine into the brachial artery (2-4 microg/min). The cardiac index was measured by thoracic bioimpedance. A 2 h period of hyperinsulinaemia increased the plasma insulin concentration to a similar degree in both sexes (females, 84 +/- 8.8 m-units/l; males, 87 +/- 7.5 m-units/l), but induced a more marked increase in forearm blood flow in females than in males (+104 +/- 67% and +52 +/- 30% respectively; P<0.01; 95% confidence interval for difference 11-94%). Furthermore, a significant decrease in total peripheral resistance (-20 +/- 6.9%; P<0.01) and an increase in cardiac index (+23 +/- 13%; P<0.01) were seen in women only (P<0.05 compared with men). Blood pressure and heart rate were not altered in either sex. Whole-body insulin-mediated glucose uptake and forearm glucose uptake did not differ between the sexes, and the ability of insulin to enhance endothelium-dependent vasodilatation (+19%; P<0.01) was similar in men and women. In conclusion, the present study shows that the ability of insulin to cause vasodilatation was greater in non-obese young women compared with men. However, no differences between the sexes were seen with regard to insulin-mediated glucose uptake and the ability of insulin to enhance endothelium-dependent vasodilatation.
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| 5. |
- Lind, Lars, et al.
(författare)
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The impairment in endothelial function induced by non-esterified fattyacids can be reversed by insulin
- 2000
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 99:3, s. 169-174
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Tidskriftsartikel (refereegranskat)abstract
- Dyslipidaemia, with elevations of circulating triacylglycerols (triglycerides) and non-esterified (free) fatty acids, and hyperinsulinaemia are often found in the same subjects, the so-called 'insulin resistance syndrome'. The present study aims to investigate how elevated levels of non-esterified fatty acids, hyperinsulinaemia and the combination of these factors affects endothelium-dependent vasodilatation (EDV). Ten volunteers were examined on two occasions. Intralipid (plus heparin) or saline (0.9% NaCl) was infused for 4 h. During the final 2 h, euglycaemic hyperinsulinaemia (80+/-4 m-units/l) was imposed. EDV and endothelium-independent vasodilatation were evaluated in the forearm by local intra-arterial infusion of methacholine or sodium nitroprusside at baseline and after 2 and 4 h. Forearm blood flow was measured by venous occlusion plethysmography. Lipid oxidation was determined by measuring plasma malondialdehyde levels. Infusion of Intralipid plus heparin increased the concentration of non-esterified fatty acids to 2.6+/-1.2 mmol/l and decreased EDV from 27.6+/-8.7 to 21.0+/-5.7 ml x min(-1) x 100 ml(-1) tissue (P < 0.01). This effect was completely reversed by hyperinsulinaemia (P < 0.01). Hyperinsulinaemia alone increased EDV (to 30.4+/-9.5 ml x min(-1) x 100 ml(-1) tissue; P < 0.01), while endothelium-independent vasodilatation was unaltered by the interventions. Infusion of Intralipid plus heparin increased malondialdehyde levels from 0.67+/-0.22 to 1.2+/-0.37 micromol/l (P < 0.001), while hyperinsulinaemiadid not change the malondialdehyde level. In conclusion, an acute increase in serum levels of non-esterified fatty acids increased lipid oxidation and decreased EDV. The effect on EDV of non-esterified fatty acids could be reversed by hyperinsulinaemia.
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| 6. |
- Linde, Torbjörn, et al.
(författare)
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Improved hemorheological properties during infusion of a lipid emulsion(Intralipid) in healthy subjects
- 2000
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Ingår i: Intensive Care Medicine. - 0342-4642 .- 1432-1238. ; 26:10, s. 1462-1465
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Lipid emulsions are commonly used for nutrition in critically ill patients. In these patients interventions resulting in deteriorated blood rheology and thereby an impaired microcirculation may be deleterious. This study examined the acute hemorrheological effects of the lipid emulsion Intralipid. We have recently shown that hyperinsulinemia exerts a negative effect on erythrocyte deformability, and here the effect of hyperinsulinemia combined with Intralipid was studied. SUBJECTS AND INTERVENTIONS: Eleven healthy subjects received Intralipid (200 mg/ml) intravenously as a bolus injection (0.5 ml/kg) over 10 min and thereafter as a continuous intravenous infusion (90 ml/h) for 4 h combined with heparin (200 U/h) to stimulate lipolysis. During the final 2 h an euglycemic hyperinsulinemic clamp was added. Five subjects underwent the same protocol with the exception that saline was given instead of Intralipid and heparin. MEASUREMENTS AND RESULTS: Whole blood viscosity, plasma viscosity, erythrocyte aggregation tendency and fluidity were measured by rotational viscometry. Compared with basal and control values the Intralipid infusion caused greater erythrocyte fluidity (p < 0.05) and less aggregation tendency (p < 0.05). Whole blood and plasma viscosity remained unchanged. Hyperinsulinemia had no significant effect on the hemorrheological variables measured. CONCLUSIONS: Intralipid has no deleterious effects on blood rheology in healthy subjects. Instead, it leads to improved erythrocyte aggregation tendency and fluidity. If the emulsion exerts the same effects in patients with impaired circulation, the use of Intralipid may be beneficial in these patients.
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| 7. |
- Sarabi, Mahziar, et al.
(författare)
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An ordinary mixed meal transiently impairs endothelium-dependent vasodilation in healthy subjects
- 2001
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 172:2, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- This study was designed to evaluate the effects of an ordinary mixed meal on endothelium-dependent vasodilation. Ten young healthy volunteers were given a mixed meal (minced meat sauce with rice, 900 kcal, 34% of the energy content was fat). In the fasting state, at 60 and 120 min after the start of the meal, endothelium-dependent vasodilation and endothelium-independent vasodilation were evaluated by local infusion of metacholine (4 microg min (-1)) and sodium nitroprusside (10 microg min (-1)) in the brachial artery. Blood flow in the forearm was measured using venous occlusion plethysmography. Endothelium-dependent vasodilation decreased from 15.4 +/- 3.3 (mean +/- SD) at fasting to 13.7 +/- 3.5 mL min (-1) (100 mL tissue)-1 (P < 0.01) 60 min after feeding, but had returned to the fasting level at 120 min. At 60 min, but not in the fasting state, the serum level of free fatty acids was inversely related to endothelium-dependent vasodilation (r=-0.74, P < 0.05), although no significant net changes in FFA levels were seen. Endothelium-independent vasodilation was not affected by the mixed meal. No similar attenuations in endothelium-dependent vasodilation were seen during control meals. In conclusion, an ordinary mixed meal transiently attenuated endothelium-dependent vasodilation. Free fatty acids may be involved in this effect on endothelial function.
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| 8. |
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| 9. |
- Steer, Peter, et al.
(författare)
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Acute elevations of medium- and long-chain fatty acids have different impacts on endothelium-dependent vasodilation in humans
- 2003
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 38:1, s. 15-19
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Tidskriftsartikel (refereegranskat)abstract
- It has previously been shown that acute elevation of long-chain fatty acids (LCFA) impairs endothelium-dependent vasodilation (EDV) in humans. In this study, we tested the hypothesis that an elevation of both medium-chain fatty acids (MCFA) and LCFA affects the endothelium differently from LCFA elevation alone. Ten healthy volunteers received an intravenous infusion of Structolipid (structured TG, MCFA/LCFA ratio 1:1) and heparin for 2 h, while another 10 subjects received an infusion of Intralipid (LCFA only) and heparin. EDV and endothelium-independent vasodilation (EIDV) were studied in the forearm after local administration of methacholine chloride (2 and 4 microg/min) and sodium nitroprusside (5 and 10 microg/min). Forearm blood flow was determined by venous occlusion plethysmography. Intralipid and heparin increased circulating FA levels from 0.2 +/- 0.1 to 1.4 +/- 0.5 mmol/L (P < 0.001) and reduced EDV by 20% (P < 0.01). Although Structolipid and heparin increased circulating FA levels to a similar extent (from 0.4 +/- 0.1 to 1.8 +/- 0.4 mmol/L after 2 h), EDV was not significantly changed. EIDV increased slightly during both interventions (P < 0.05). In conclusion, an acute elevation of LCFA attenuated EDV, whereas an elevation of both MCFA and LCFA did not influence EDV. Thus, FA composition seems to be of importance for EDV in healthy humans.
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| 10. |
- Steer, Peter, et al.
(författare)
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The effect of a mixed meal on endothelium-dependent vasodilation is dependent on fat content in healthy humans
- 2003
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Ingår i: Clinical Science. - 0143-5221 .- 1470-8736. ; 105:1, s. 81-87
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Tidskriftsartikel (refereegranskat)abstract
- Impaired endothelium-dependent vasodilation (EDV) is an early marker of atherosclerosis. The aim of the present study was to investigate how meals with different fat contents influence endothelial vasodilatory function. A total of 26 young, healthy men and women aged 20-30 years ingested an ordinary Western meal [34 energy% (E%) fat, n =10], or isocaloric meals with low-fat (20 E%, n =8), or minimal-fat (3 E%, n =8) content. EDV was assessed as forearm blood flow (FBF) during local administration of 4 microg/min methacholine chloride (Mch-FBF) and endothelium-independent vasodilation as FBF during administration of 10 microg/min sodium nitroprusside (SNP-FBF) at baseline and 1 and 2 h after each meal. FBF was determined by venous occlusion plethysmography. An endothelial function index (EFI) was calculated as the Mch-FBF/SNP-FBF ratio. Both Mch-FBF and the EFI were decreased at 1 h after the 34 E% fat meal ( P <0.01 and P <0.05 respectively), but approached fasting levels after 2 h. Mch-FBF and EFI did not change significantly in the group consuming the 20 E% fat meal, but increased in the 3 E% fat group ( P <0.01 and P <0.05 compared with baseline for Mch-FBF and EFI respectively). SNP-FBF was not significantly affected by any of the meals. In conclusion, low-fat meals did not attenuate EDV, in contrast with an ordinary Western meal, which transiently impaired EDV. Our findings indicate that a dietary fat content of 20 E% or less might be beneficial to endothelial vasodilatory function.
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