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  • 1
    ISSN: 1432-5233
    Keywords: Key words Glucose ; Insulin ; Hyperinsulinaemia ; Blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Insulin-mediated stimulation of blood flow to skeletal muscle has been proposed to be of major importance for insulin-mediated glucose uptake. The aim of this study was to investigate the relative importance of blood flow and glucose extraction as determinants of insulin-mediated glucose uptake in the human forearm. Forearm blood flow (FBF), glucose extraction and oxygen consumption were evaluated for 100 min during the euglycaemic hyperinsulinaemic clamp (92 mU/l) in nine healthy subjects. FBF was measured by venous occlusion plethysmography. Forearm glucose uptake increased sevenfold during the hyperinsulinaemia (P〈0.001). Forearm glucose extraction showed a minor increase during the first 10 min of hyperinsulinaemia, but the most marked increase took place between 10 and 20 min (+170%). Thereafter, only a minor further increase was seen. During the first 10 min of hyperinsulinaemia FBF was unchanged. Thereafter, FBF increased steadily to a plateau reached after 60 min (+50%, P〈0.001). A close relationship between whole body glucose uptake and FBF was seen at the end of the clamp (r = 0.75, P〈0.02), but at this time the relationship between whole body glucose uptake and forearm glucose extraction was not significant. The modest increase in O2 consumption seen at the beginning of the clamp (+19%) was not related to FBF during the early phase of the clamp. In conclusion, the early course of insulin-mediated glucose uptake in the human forearm was mainly due to an increase in glucose extraction. However, with time the insulin-mediated increase in blood flow increased in importance and after 100 min of hyperinsulinaemia FBF was the major determinant of glucose uptake.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-5233
    Keywords: Insulin-dependent diabetes mellitus ; Hypoglycaemia ; Skin blood flow ; Reactive hyperaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to compare the cutaneous postischaemic hyperaemic response in young insulin-dependent diabetic patients and healthy subjects during normoglycaemia, acute insulin-induced hypoglycaemia and in the posthypoglycaemic state. After a night of normoglycaemia the cutaneous postischaemic hyperaemic response in the forearm skin, measured by the transcutaneousPO 2 method, was the same in both groups. A reduction of the maximal postischaemic vasodilatory response was observed in diabetic patients from 2.4±0.3 to 2.0±0.2 kPa (P〈0.05) and in control subjects from 2.7±0.3 to 1.8±0.2 kPa (P〈0.02) during insulin-induced hypoglycaemia (plasma glucose〈2 mmol/l). Complete recovery of the vasodilatory response occurred in subjects in the posthypoglycaemic state. We conclude that hypoglycaemia induced a transient reduction of the vasodilatory response, which was rapidly reversed after glucose counter-regulation, in both diabetic patients and healthy controls. Thus, the prevailing blood glucose concentration must be taken into account when the postischaemic vasodilatory response is investigated in diabetic patients.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-5233
    Keywords: Key words Hypoglycaemia ; Gastric emptying ; Atropine ; Motilin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study examined whether or not changes in plasma concentrations of motilin and other gastrointestinal hormones known to affect gastric motility are associated with the accelerated gastric emptying seen during hypoglyc-aemia. While studying gastric emptying by scintigraphy in eight healthy subjects, the plasma concentrations of glucagon, adrenaline, motilin, gastrin, neuropeptide Y and somatostatin were measured during normoglycaemia and hypoglycaemia with simultaneous infusion of either atropine or saline. Blood glucose concentrations were checked by an insulin-glucose clamp. The plasma levels of glucagon and adrenaline increased markedly during both hypoglycaemic examinations compared with normoglycaemia. Neither motilin nor any of the other hormones displayed considerable changes during hypoglycaemia with and without atropine compared with normoglycaemia. No further information about the mechanisms behind the accelerated gastric emptying rate during hypoglycaemia was obtained by analysing motilin and the other gastrointestinal hormones.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytical Biochemistry 50 (1972), S. 50-55 
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Analytical Biochemistry 78 (1977), S. 229-234 
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0992-7689
    Keywords: Hydrology (evapotranspiration; soil moisture; water-energy interactions)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provide continuous time series of field data over a long period, in order to improve and validate the Soil-vegetation-Atmosphere Transfer (SVAT) parameterisations employed in meteorological models. Intensive measurements were performed for more than three years over fallow farmland in southwestern France. To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterised, and surface water and energy fluxes, vegetation biomass, soil moisture profiles, surface soil moisture and surface and soil temperature were monitored. Additional physiological measurements were carried out during selected periods to describe the biological control of the fluxes. The MUREX data of 1995, 1996, and 1997 are presented. Four SVAT models are applied to the annual cycle of 1995. In general, they succeed in simulating the main features of the fallow functioning, although some shortcomings are revealed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Keywords Renin-angiotensin system ; ACE inhibitor ; angiotensin II ; pancreatic islets ; insulin release ; islet microcirculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An intrinsic angiotensin system has been described in the pancreas, with angiotensin II specific receptors being present on both exocrine, endocrine and vascular cells. The aim of the present study was to evaluate the effects of angiotensin II on insulin secretion and blood flow regulation in the pancreas. Blood flows were determined with a microsphere technique. Infusion of angiotensin II induced a dose-dependent reduction in both whole pancreatic and islet blood flow, which was most pronounced in the former. Administration of enalaprilate, an inhibitor of angiotensin-converting enzyme, and saralasin, a non-selective angiotensin II receptor antagonist, preferentially increased islet blood flow. The effects of angiotensin II on insulin release were examined by measuring insulin concentrations in the effluents from isolated perfused pancreata. In these preparations, enalaprilate affected neither basal nor glucose-stimulated insulin release, whereas angiotensin II delayed the first phase of insulin release in response to glucose. The effect of angiotensin II was probably due to initial marked vasoconstriction. The retardation of insulin release could be avoided by adding angiotensin II to the perfusion medium 20 min before glucose administration, i. e. so that the vasoconstriction had disappeared when glucose-stimulation began. The present study suggests that the angiotensin-system is important in regulation of islet blood flow and points to a pivotal role of islet blood perfusion for an adequate insulin release. [Diabetologia (1998) 41: 127–133]
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 29 (1986), S. 855-860 
    ISSN: 1432-0428
    Keywords: Hypoglycaemia ; sympathetic nervous system ; skin nerve sympathetic activity ; microelectrode recording ; thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Microclectrode recordings of skin nerve sympathetic activity, consisting of sudomotor and vasoconstrictor signals, were performed in the peroneal nerve in seven healthy subjects during insulin-induced hypoglycaemia. The nerve activity was recorded at rest and for 90 min after intravenous injection of 0.15 IIJ insulin/kg body weight. The net outflow of skin nerve sympathetic activity was increased during hypoglycaemia, with the exception of one subject who exhibited a high initial level of activity. In all subjects a change of the temporal pattern of the outflow was found, suggesting a shift from mixed (sudomotor and vasoconstrictor) to pure sudomotor activity. This change coincided with a sensation of warmth, sweating and varying degrees of cutaneous vasodilatation, and was followed by a fall in body temperature. It is concluded that hypoglycaemia has a differential effect on sympathetic activity in skin nerves, with a strong increase of sudomotor impulses and simultaneous inhibition of vasoconstrictor signals. Thus, neurally mediated thermoregulatory adjustment contributes to heat loss during hypoglycaemia.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 35 (1992), S. 873-879 
    ISSN: 1432-0428
    Keywords: Sympathetic nervous system ; catecholamines ; insulin ; blood pressure ; glucose metabolism ; hypertension ; insulin resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sympathetic nervous system activation by insulin has been suggested as a mechanism explaining the association between insulin resistance and hypertension. We further examined the effect of insulin by direct microneurographic muscle and skin nerve sympathetic activity recordings during euglycaemic insulin clamps in healthy subjects. The mean plasma insulin level was elevated from 5.3±0.7 to 92.2±2.2 mU/l in seven subjects during a 90-min one-step clamp. In six other subjects plasma insulin was further raised from 85.7±4.0 mU/l to 747±53 mU/l between 45–90 min (two-step clamp). Four of the latter subjects received a sham clamp with NaCl infusions only on a second recording session. At the low dose of insulin muscle nerve sympathetic activity increased from a resting level of 22.7±5.0 bursts per min to 27.7±5.0 bursts per min at 15 min (p〈0.05). The increases in muscle nerve sympathetic activity were significant (p〈0.001; ANOVA) throughout insulin infusion, with a slight further increase (from 29.2±1.6 to 32.3±1.9 bursts per min) at the supraphysiological insulin concentration. During sham clamps muscle nerve sympathetic activity did not increase. Both insulin clamps induced minor, but significant, increases in forearm venous plasma noradrenaline concentrations. Skin nerve sympathetic activity (n=3) did not change during insulin infusions. Heart rate increased slightly but significantly (p〈0.005), during the insulin clamps. Blood pressure was not notably affected. In conclusion, hyperinsulinaemia was associated with increased vasoconstrictor nerve activity to skeletal muscle and with no change of sympathetic outflow to skin.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 24 (1983), S. 202-206 
    ISSN: 1432-0428
    Keywords: Phosphatidyl glycerol ; diabetic pregnancy ; fetal lung ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The lungs of fetuses of streptozotocin-diabetic rats were examined for their ability to incorporate U-14C-glucose into phosphatidyl choline, phosphatidyl glycerol, phosphatidyl inositol and lysophosphatidyl choline. In the lungs of control rats an increased biosynthesis of phosphatidyl glycerol in late pregnancy suggested a close association between the production of this phospholipid and the terminal maturation of the fetal lung. In the offspring of diabetic rats the incorporation of 14C-glucose into phosphatidyl choline, lysophosphatidyl choline and phosphatidyl glycerol was markedly decreased compared with the control rats on gestational day 20, whereas no difference was seen at day 22. Insulin treatment of the pregnant rats restored the biosynthesis of phosphatidyl choline and lysophosphatidyl choline towards normal on gestational day 20, while the ratio of phosphatidyl glycerol to phosphatidyl inositol incorporation of 14C-glucose was decreased, suggesting that the biosynthesis of phosphatidyl glycerol is more sensitive than that of phosphatidyl choline and lysophosphatidyl choline to the metabolic disturbances inherent in maternal diabetes. The delayed fetal pulmonary maturation occurred without fetal hyperinsulinism which suggests that this latter feature may not be of crucial significance in the aetiology of the respiratory distress syndrome.
    Type of Medium: Electronic Resource
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