An enzymatic fluorometric micromethod for the determination of glycerol

Laurell, S.; Tibbling, G

doi:10.1016/0009-8981(66)90210-5

Cited by 419 publications

(131 citation statements)

References 2 publications

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“…Plasma levels of lactate were measured using a kit (Instruchemie, Delfzijl, the Netherlands). Glycerol was measured in deproteinised, neutralised medium extracts [20] according to the enzymatic method of Laurell and Tibbling [21].…”

Section: Methodsmentioning

confidence: 99%

Carnitine revisited: potential use as adjunctive treatment in diabetes

et al. 2007

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Aims/hypothesis This study examined the efficacy of supplemental L-carnitine as an adjunctive diabetes therapy in mouse models of metabolic disease. We hypothesised that carnitine would facilitate fatty acid export from tissues in the form of acyl-carnitines, thereby alleviating lipidinduced insulin resistance. Materials and methods Obese mice with genetic or dietinduced forms of insulin resistance were fed rodent chow ± 0.5% L-carnitine for a period of 1-8 weeks. Metabolic outcomes included insulin tolerance tests, indirect calorimetry and mass spectrometry-based profiling of acyl-carnitine esters in tissues and plasma.Results Carnitine supplementation improved insulin-stimulated glucose disposal in genetically diabetic mice and wild-type mice fed a high-fat diet, without altering body weight or food intake. In severely diabetic mice, carnitine supplementation increased average daily respiratory exchange ratio from 0.886±0.01 to 0.914±0.01 (p<0.01), reflecting a marked increase in systemic carbohydrate oxidation. Similarly, under insulin-stimulated conditions, carbohydrate oxidation was higher and total energy expenditure increased from 172±10 to 210±9 kJ kg fatfree mass −1 h −1 in the carnitine-supplemented compared with control animals. These metabolic improvements corresponded with a 2.3-fold rise in circulating levels of acetyl-carnitine, which accounts for 86 and 88% of the total acyl-carnitine pool in plasma and skeletal muscle, respectively. Carnitine supplementation also increased several medium-and long-chain acyl-carnitine species in both plasma and tissues. Conclusions/interpretation These findings suggest that carnitine supplementation relieves lipid overload and glucose intolerance in obese rodents by enhancing mitochondrial efflux of excess acyl groups from insulin-responsive tissues. Carefully controlled clinical trials should be considered.

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Section: Methodsmentioning

confidence: 99%

Carnitine revisited: potential use as adjunctive treatment in diabetes

et al. 2007

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“…Plasma catecholamine concentrations were determined by a well validated technique using high performance cation exchange liquid chromatography with electrochemical detection (Hjemdahl et al, 1979;Hjemdahl, 1987). Plasma cyclic AMP was measured by a protein binding method (Brown et al, 1972) and plasma glycerol by an enzymatic fluorometric method (Laurell & Tibbling, 1966). Metoprolol and propranolol were determined by gas chromatography (Ervik, 1975) and hydrochlorothiazide by high performance liquid chromatography.…”

Section: Methodsmentioning

confidence: 99%

Responses to mental stress and physical provocations before and during long term treatment of hypertensive patients with beta‐adrenoceptor blockers or hydrochlorothiazide.

Eliasson

Kahan

Hylander

et al. 1987

Brit J Clinical Pharma

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1 Cardiovascular and sympatho-adrenal responsiveness to mental stress (CWT; a colour word test), orthostatic testing (ORT) and a cold pressor test (CPT) were examined in three groups of hypertensive patients (n = 14-16) before and after 6 months treatment with metoprolol (243 ± 26 mg daily), propranolol (149 ± 16 mg daily) or hydrochlorothiazide (50 ± 8 mg daily) in an open trial design. 2 Treatment reduced outpatient blood pressures in the three groups similarly (from approximately 155/102 to 135/90 mm Hg). During treatment resting blood pressures in the laboratory were clearly reduced by P-adrenoceptor blockade but not by thiazide treatment. Metoprolol and propranolol caused similar reductions of basal heart rates and plasma glycerol levels, whereas only propranolol reduced cyclic AMP concentrations in plasma. 3 Before treatment CWT and CPT increased systolic and diastolic blood pressures by about 30%. Heart rate increased by about 30 beats min-' during CWT and 10-15 beats min-' during CPT and ORT. Small venous plasma adrenaline responses were evoked by all tests, whereas noradrenaline was elevated mainly by CPT and ORT. Dopamine levels did not change. 4 Heart rate responses to all stressors were markedly and similarly reduced, whereas blood pressure responses were essentially unchanged during metoprolol or propranolol treatment. In the thiazide group circulatory responses to CWT were slightly attenuated, whereas responses to ORT and CPT were unchanged. 5 The systolic blood pressure levels were reduced throughout the test session in all three groups, although less so in the hydrochlorothiazide group. Both 3-adrenoceptor antagonists clearly reduced diastolic blood pressure and heart rate levels at rest and during stress, whereas thiazide treatment caused no significant changes in these respects. 6 The rate pressure product, which increased by 80-100% in response to CWT before treatment, was more markedly reduced by 3-adrenoceptor blockade than by thiazide treatment both at rest and during stress.7 Self ratings (visual analogue scales) of stress and irritation were increased by CWT in a similar fashion before and during treatment in all groups. ,B-adrenoceptor blockade was associated with higher subjective ratings of tiredness at rest, but not after CWT. Perfor-

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“…and with 0.15 gCi [1--14C] glucose (New England Nuclear, Boston, Mass., USA) and the indicated concentrations of insulin or noradrenaline (Astra AB, S~Sdert~ilje, Sweden). Glycerol was determined on the incubation medium as described by Laurell and Tibbling [6].…”

Section: Methodsmentioning

confidence: 99%

Human adipose tissue in culture V. Studies on the metabolic effects of insulin

1976

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Summary.Specimens of human adipose tissue were cultured for one week with or without the addition of insulin. The basal as well as the noradrenaline-stimulated lipolysis were enhanced in the explants cultured with insulin, showing that the long-term effect of the hormone is lipolytic. However, an acute antilipolytic effect of insulin could be demonstrated in these explants in the subsequent short-term incubations. The basal rate of glucose incorporation into the lipids was enhanced in the explants cultured with insulin. When insulin was added in the short-term incubations these explants did not further respond to the hormone while this was the case with the explants cultured without insulin. Thus, it seems that prolonged exposure to insulin leads to a diminished acute effect of the hormone on glucose metabolism. However, the same explants responded to the antilipolytic effect showing that insulin was able to bind itself to the membrane. The activities of hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PDH), pyruvate kinase (PK) and lactate dehydrogenase (LDH) were increased in large fat cells both in freshly excised tissue and in the cultured explants. However, the activity of phosphofructokinase (PFK) did not correlate with the cell size. The presence of insulin during the culture period enhanced the activities of G6PDH, PK, and LDH, while this was not found for HK or PFK. The data thus suggest that the metabolic capacity of human fat cells is enhanced by long-term exposure to insulin. Although enzyme induction could be shown for G6PDH, PK and LDH it seems unlikely that this is of importance for the increased rates of glucose metabolism in these explants since the rate-limiting enzymes, HK and PFK, were not increased. Most probably, *Part of these data were presented at the First International Congress on Obesity in London, England on 9-11 October, 1974. then, this stimulating effect of insulin is exerted on the membrane and the rate of glucose transport.

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An enzymatic fluorometric micromethod for the determination of glycerol

Cited by 419 publications

References 2 publications

Carnitine revisited: potential use as adjunctive treatment in diabetes

Carnitine revisited: potential use as adjunctive treatment in diabetes

Responses to mental stress and physical provocations before and during long term treatment of hypertensive patients with beta‐adrenoceptor blockers or hydrochlorothiazide.

Human adipose tissue in culture V. Studies on the metabolic effects of insulin

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