RESUMEN
AIMS/HYPOTHESIS: It is not known whether the beneficial effects of exercise training on insulin sensitivity are due to changes in hepatic and peripheral insulin sensitivity or whether the changes in insulin sensitivity can be explained by adaptive changes in fatty acid metabolism, changes in visceral fat or changes in liver and muscle triacylglycerol content. We investigated the effects of 6 weeks of supervised exercise in sedentary men on these variables. SUBJECTS AND METHODS: We randomised 17 sedentary overweight male subjects (age 50 +/- 2.6 years, BMI 27.6 +/- 0.5 kg/m(2)) to a 6-week exercise programme (n = 10) or control group (n = 7). The insulin sensitivity of palmitic acid production rate (Ra), glycerol Ra, endogenous glucose Ra (EGP), glucose uptake and glucose metabolic clearance rate were measured at 0 and 6 weeks with a two-step hyperinsulinaemic-euglycaemic clamp [step 1, 0.3 (low dose); step 2, 1.5 (high dose) mU kg(-1) min(-1)]. In the exercise group subjects were studied >72 h after the last training session. Liver and skeletal muscle triacylglycerol content was measured by magnetic resonance spectroscopy and visceral adipose tissue by cross-sectional computer tomography scanning. RESULTS: After 6 weeks, fasting glycerol, palmitic acid Ra (p = 0.003, p = 0.042) and NEFA concentration (p = 0.005) were decreased in the exercise group with no change in the control group. The effects of low-dose insulin on EGP and of high-dose insulin on glucose uptake and metabolic clearance rate were enhanced in the exercise group but not in the control group (p = 0.026; p = 0.007 and p = 0.04). There was no change in muscle triacylglycerol and liver fat in either group. CONCLUSIONS/INTERPRETATION: Decreased availability of circulating NEFA may contribute to the observed improvement in the insulin sensitivity of EGP and glucose uptake following 6 weeks of moderate exercise.
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Glucemia/metabolismo , Ejercicio Físico , Ácidos Grasos/metabolismo , Insulina/farmacología , Sobrepeso , Glucemia/efectos de los fármacos , Índice de Masa Corporal , Ácidos Grasos no Esterificados/sangre , Técnica de Clampeo de la Glucosa , Humanos , Estilo de Vida , Masculino , Persona de Mediana Edad , Ácido Palmítico/sangreRESUMEN
GH is an important regulator of fat metabolism at rest, but it is not known whether it regulates fat metabolism during exercise. To determine whether physiologic concentrations of GH influence fat metabolism during exercise, we randomized 16 GH-deficient adults, receiving long-term (mean duration, 5 yr) GH replacement, to either continue GH (n = 8) or receive identical placebo (n = 8) for a 3-month period. Metabolic studies, at rest, during and following exhaustive exercise were carried out at baseline and at the end of the 3 months. The rate of appearance of glycerol (glycerol Ra, an index of lipolysis) and free fatty acids (FFA, FFA Ra) and the rate of disappearance of FFA (FFA Rd) in the plasma were measured using infusions of (2)H(5)-glycerol and 1-(13)C-palmitic acid. Changes in body composition were assessed using dual-energy x-ray absorptiometry scanning and anthropometric measurements. In the baseline studies, exercise resulted in an increase in plasma glycerol and FFA concentrations, glycerol Ra, FFA Ra, and FFA Rd (P < 0.001). Three months of GH withdrawal resulted in reductions in plasma glycerol and FFA, glycerol Ra, FFA Ra, and FFA Rd at rest (P < 0.05 vs. baseline) and during exercise (P < 0.05 vs. baseline and vs. GH treated). Lean body mass decreased after 3 months of GH withdrawal, but total body fat, trunk fat, waist circumference, and the sum of skinfold thicknesses increased after 3 months of GH withdrawal (P < 0.05 vs. baseline and vs. GH treated). Fasting insulin and homeostasis model assessment of insulin resistance decreased after 3 months of GH withdrawal (P < 0.05 vs. baseline and vs. GH treated). In summary, GH withdrawal for 3 months resulted in reductions in release of glycerol and FFA into the circulation and uptake of FFA into the tissues during intense exercise. These changes were accompanied by reduced lean body mass and increased total body and trunk fat. Further studies are required to determine whether reduced mobilization of fat during exercise contributes to reduced exercise capacity and increased body fat in GH-deficient adults.
Asunto(s)
Ejercicio Físico/fisiología , Ácidos Grasos no Esterificados/sangre , Glicerol/sangre , Hormona de Crecimiento Humana/administración & dosificación , Hormona de Crecimiento Humana/deficiencia , Absorciometría de Fotón , Tejido Adiposo , Adulto , Aerobiosis , Anciano , Composición Corporal , Constitución Corporal , Isótopos de Carbono , Deuterio , Método Doble Ciego , Ayuno , Femenino , Homeostasis , Hormona de Crecimiento Humana/uso terapéutico , Humanos , Insulina/sangre , Resistencia a la Insulina , Factor I del Crecimiento Similar a la Insulina/análisis , Cinética , Lipólisis , Masculino , Persona de Mediana Edad , Placebos , Grosor de los Pliegues CutáneosRESUMEN
Type 1 diabetes is associated with abnormalities of the growth hormone (GH)-IGF-I axis. Such abnormalities include decreased circulating levels of IGF-I. We studied the effects of IGF-I therapy (40 microg x kg(-1) x day(-1)) on protein and glucose metabolism in adults with type 1 diabetes in a randomized placebo-controlled trial. A total of 12 subjects participated, and each subject was studied at baseline and after 7 days of treatment, both in the fasting state and during a hyperinsulinemic-euglycemic amino acid clamp. Protein and glucose metabolism were assessed using infusions of [1-13C]leucine and [6-6-2H2]glucose. IGF-I administration resulted in a 51% rise in circulating IGF-I levels (P < 0.005) and a 56% decrease in the mean overnight GH concentration (P < 0.05). After IGF-I treatment, a decrease in the overnight insulin requirement (0.26+/-0.07 vs. 0.17+/-0.06 U/kg, P < 0.05) and an increase in the glucose infusion requirement were observed during the hyperinsulinemic clamp (approximately 67%, P < 0.05). Basal glucose kinetics were unchanged, but an increase in insulin-stimulated peripheral glucose disposal was observed after IGF-I therapy (37+/-6 vs. 52+/-10 micromol x kg(-1) x min(-1), P < 0.05). IGF-I administration increased the basal metabolic clearance rate for leucine (approximately 28%, P < 0.05) and resulted in a net increase in leucine balance, both in the basal state and during the hyperinsulinemic amino acid clamp (-0.17+/-0.03 vs. -0.10+/-0.02, P < 0.01, and 0.25+/-0.08 vs. 0.40+/-0.06, P < 0.05, respectively). No changes in these variables were recorded in the subjects after administration of placebo. These findings demonstrated that IGF-I replacement resulted in significant alterations in glucose and protein metabolism in the basal and insulin-stimulated states. These effects were associated with increased insulin sensitivity, and they underline the major role of IGF-I in protein and glucose metabolism in type 1 diabetes.
Asunto(s)
Diabetes Mellitus Tipo 1/terapia , Factor I del Crecimiento Similar a la Insulina/uso terapéutico , Adulto , Aminoácidos/metabolismo , Aminoácidos/farmacología , Ritmo Circadiano , Diabetes Mellitus Tipo 1/sangre , Electrólitos , Ayuno/fisiología , Femenino , Glucosa/metabolismo , Técnica de Clampeo de la Glucosa , Hormona de Crecimiento Humana/metabolismo , Humanos , Hiperinsulinismo/metabolismo , Hipoglucemiantes/uso terapéutico , Insulina/uso terapéutico , Factor I del Crecimiento Similar a la Insulina/análisis , Masculino , Persona de Mediana Edad , Soluciones para Nutrición Parenteral , Proteínas/metabolismo , SolucionesRESUMEN
Growth hormone (GH) treatment of GH-deficient adults increases lean body mass. To investigate this anabolic effect of GH, body composition and postabsorptive and postprandial protein metabolism were measured in 12 GH-deficient adults randomized to placebo or GH treatment. Protein metabolism was measured after an infusion of [1-13C]leucine before and after a standard meal at 0 and 2 mo. After 2 mo, there was an increase in lean body mass in the GH group (P < 0. 05) but no change in the placebo group. In the postabsorptive state, there was increased nonoxidative leucine disappearance (NOLD; a measure of protein synthesis) and leucine metabolic clearance rate and decreased leucine oxidation in the GH group (P < 0.05) but no change in the placebo group. After the meal, there was an increase in NOLD and oxidation in all studies (P < 0.05), but the increase in NOLD, measured as area under the curve, was greater in the GH group (P < 0.05). This study clearly demonstrates for the first time that the increase in protein synthesis in the postabsorptive state after GH treatment of GH-deficient adults is maintained in the postprandial state.
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Alimentos , Hormona de Crecimiento Humana/deficiencia , Hormona de Crecimiento Humana/farmacología , Biosíntesis de Proteínas , Adulto , Composición Corporal , Péptido C/sangre , Isótopos de Carbono , Ácidos Grasos no Esterificados/sangre , Femenino , Hormona de Crecimiento Humana/uso terapéutico , Humanos , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leucina , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , PlacebosRESUMEN
Cushing's syndrome is characterized by central obesity and muscle wasting. As GH is anabolic, it may be able to counteract the loss of body protein. To evaluate the potential therapeutic use of GH preoperatively, eight patients with Cushing's syndrome received sc injections of recombinant human GH (0.07 U/kg.day) for 7 days. Whole body leucine and glucose turnover were measured after an infusion of [1-13C]leucine and [6,6-2H2]glucose before (day 0) and after 2 and 7 days of GH treatment. Compared with the value on day 0, there was a significant increase on days 2 and 7 in insulin (P < 0.005 and P < 0.001), C peptide (P < 0.01 and P < 0.005), insulin-like growth factor I (P < 0.001), and glucose concentrations (P < 0.01 and P < 0.005) and a decrease in the leucine concentration (P < 0.005). There was no significant change in glucose production rate, glucose MCR, leucine production rate (a measure of protein degradation), or nonoxidative leucine disappearance rate (a measure of protein synthesis). The leucine MCR was increased after 7 days (P < 0.05), and the clearance of leucine into protein (nonoxidative leucine disappearance rate/leucine concentration) was increased (P < 0.05) after 2 and 7 days of GH treatment. This is consistent with GH stimulating the availability of amino acid transporters. GH may, therefore, have a therapeutic role in the preoperative treatment of Cushing's syndrome.
Asunto(s)
Glucemia/metabolismo , Síndrome de Cushing/metabolismo , Hormona de Crecimiento Humana/uso terapéutico , Leucina/metabolismo , Adulto , Péptido C/sangre , Femenino , Humanos , Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Proteínas Recombinantes/uso terapéutico , Valores de ReferenciaRESUMEN
Gestational diabetes affects 2-3% of pregnant women and is associated with foetal complications including macrosomia and an increased likelihood of developing diabetes in later life. We have therefore studied seven women with gestational diabetes and five control women both during the third trimester of pregnancy and again 2-3 months post-partum, using the minimal model analysis of the frequently sampled labelled ([6,6-2H2]-glucose) intravenous glucose tolerance test. Glucose tolerance (glucose Kd) was significantly reduced in the women with gestational diabetes compared with the normal pregnant women both in pregnancy (1.16 +/- 0.11 vs 1.78 +/- 0.23%/min; p < 0.05) and post-partum (1.47 +/- 0.22 vs 2.59 +/- 0.43%/min; p < 0.05) and increased significantly in the control women after delivery (p < 0.05). Glucose effectiveness was not significantly different between the women with gestational diabetes and the control group either during or after pregnancy. Insulin sensitivity was significantly lower during pregnancy than after delivery in the women with gestational diabetes (p < 0.05). There was no significant difference in basal insulin secretion in the two groups during pregnancy or post-partum. However, during pregnancy the control subjects significantly increased (p < 0.001) their insulin secretion over a period of 20 min in response to an intravenous glucose tolerance test (96.2 +/- 42.7 pmol/kg) compared with post-partum values (58.3 +/- 25.2 pmol/kg) while in the women with gestational diabetes insulin secretion was similar in pregnancy (65.5 +/- 9.3 pmol/kg) and after delivery (57.7 +/- 15.7 pmol/kg). These data suggest that the glucose intolerance in gestational diabetes compared to normal pregnancy is due to reduced insulin sensitivity and an impaired ability in gestational diabetes to increase insulin secretion in response to glucose.
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Glucemia/metabolismo , Diabetes Gestacional/metabolismo , Insulina/metabolismo , Embarazo/metabolismo , Adulto , Péptido C/sangre , Péptido C/metabolismo , Diabetes Gestacional/fisiopatología , Ayuno/sangre , Femenino , Humanos , Insulina/sangre , Secreción de Insulina , Periodo Posparto , Valores de Referencia , Sensibilidad y EspecificidadRESUMEN
The net catabolic effect of glucocorticoids on protein metabolism is well documented but the acute and chronic effect of glucocorticoids on protein breakdown remains controversial. In the present studies protein breakdown was measured by the release of tyrosine from the isolated soleus and extensor digitorum longus (EDL) muscles of control rats and rats treated with corticosterone (10 mg/100 g body weight/day) for 5 days. The effect of corticosterone in arresting growth was confirmed since corticosterone-treated rats weighed significantly less than control rats after 2, 3, 4 and 5 days of treatment (P < 0.001). Furthermore, the weights of soleus and EDL muscles from corticosterone-treated rats were significantly reduced (P < 0.001, at least P < 0.05 respectively) compared with muscles from control rats on days 3-5. In the EDL muscle tyrosine release was significantly elevated after corticosterone treatment for 2 days (257 +/- 21 nmol/g tissue/h, P < 0.05), 3 days (205 +/- 9 nmol/g tissue/h, P < 0.01), 4 days (255 +/- 20 nmol/g tissue/h, P < 0.005) and 5 days (218 +/- 8 nmol/g tissue/h, P < 0.05) compared with EDL from control rats (192 +/- 13, 171 +/- 7, 187 +/- 7, 180 +/- 12 nmol/g tissue/h respectively). In the soleus muscle, tyrosine release was significantly elevated after corticosterone treatment for 2 days (226 +/- 14 nmol/g tissue/h, P < 0.001), 3 days (223 +/- 16 nmol/g tissue/h, P < 0.001) and 4 days (199 +/- 10 nmol/g tissue/h, P < 0.001) compared with control rats (158 +/- 7, 132 +/- 6 and 153 +/- 7 nmol/g tissue/h respectively). After 5 days there was no significant difference in tyrosine release from soleus muscle between corticosterone-treated (176 +/- 15 nmol/g tissue/h) and control rats (157 +/- 6 nmol/g tissue/h). Plasma glucose concentrations were not significantly different in rats treated with corticosterone and control rats whilst insulin levels were significantly raised in the corticosterone-treated rats on all days compared with control rats (P < 0.05 on day 1; P < 0.001 on days 2, 3, 4 and 5). It is suggested that insulin may have prevented hyperglycaemia developing in the corticosterone-treated rats. Results from these studies indicate that the acute effect of glucocorticoids is to increase muscle proteolysis but this is not maintained with longer-term treatment.
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Corticosterona/farmacología , Proteínas Musculares/metabolismo , Músculo Esquelético/efectos de los fármacos , Animales , Glucemia/metabolismo , Técnicas de Cultivo , Insulina/sangre , Masculino , Músculo Esquelético/metabolismo , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Tirosina/metabolismoRESUMEN
The metabolic and cardiovascular effects of recombinant human IGF-I were compared to insulin in six normal subjects. Subjects were studied twice and intravenously received an infusion of [6,6-2H2]glucose (0-480 min) and in random order either IGF-I 20 micrograms kg-1 h-1 (43.7 pmol kg-1 min-1 or insulin 0.5 mU kg-1 min-1 (3.4 pmol kg-1 min-1) with an euglycaemic clamp. One subject was withdrawn following a serious adverse event. During the IGF-I infusion glucose appearance rate (Ra) decreased from 1.79 +/- 0.13 at baseline (150-180 min) to 0.35 +/- 0.26 mg kg-1 min-1 (P < 0.01) at 360 min, and glucose utilization rate (Rd) increased from 1.79 +/- 0.28 to 4.17 +/- 0.84 mg kg-1 min-1 (P < 0.01). There was no change in free fatty acids (FFA) and an increase (percentage change from pre-infusion mean) in cardiac output +l37.3% +/- 9% (P < 0.01), heart rate +13% +/- 2% (P < 0.01) and stroke volume +21% +/- 7% (P < 0.05). During the insulin infusion glucose Ra decreased from 1.89 +/- 0.13 to 0.34 +/- 0.33 mg kg-1 min-1 (P < 0.01) and FFA from 0.546 mmol l-1 to 0.198 mmol l-1 (P < 0.01), glucose Rd increased from 1.89 +/- 0.18 to 5.41 +/- 1.47 mg kg-1 min-1 (P < 0.01) and there were no significant changes in the cardiovascular variables.
Asunto(s)
Grasas/metabolismo , Glucosa/metabolismo , Hemodinámica/efectos de los fármacos , Factor I del Crecimiento Similar a la Insulina/farmacología , Insulina/farmacología , Adulto , Ácidos Grasos no Esterificados/sangre , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Insulin-like growth factor I (IGF-I) is thought to mediate the anabolic action of growth hormone. A glucose and amino acid clamp technique was used to investigate the effects of a 3-h intravenous infusion of either 43.7 pmol.kg-1.min-1 (20 micrograms.kg-1.h-1) IGF-I or 3.4 pmol.kg-1.min-1 (0.5 mU.kg-1.min-1) insulin on whole body leucine turnover in five normal human volunteers. During the IGF-I infusion, IGF-I levels increased (P < 0.01; 26.6 +/- 2.8 to 88.9 +/- 14.2 nmol/l) and insulin levels fell (P < 0.05; 0.096 +/- 0.018 to 0.043 +/- 0.009 nmol/l). During the insulin infusion, insulin levels increased (P < 0.01; 0.057 +/- 0.013 to 0.340 +/- 0.099 nmol/l), and there was no change in IGF-I. There was no significant change in leucine production rate (Ra; a measure of protein degradation) during the IGF-I infusion (2.23 +/- 0.17 to 2.13 +/- 0.2 mumol.kg-1.min-1), but there was an increase (P < 0.03) in nonoxidative leucine disposal rate (Rd; a measure of protein synthesis; 1.83 +/- 0.15 to 2.05 +/- 0.21 mumol.kg-1.min-1). In contrast, insulin reduced (P < 0.02) leucine Ra (1.81 +/- 0.24 to 1.47 +/- 0.24 mumol.kg-1.min-1) and had no effect on nonoxidative leucine Rd (1.44 +/- 0.25 to 1.41 +/- 0.22 mumol.kg-1.min-1). We conclude that IGF-I, under conditions of adequate substrate supply, directly increases protein synthesis in contrast to insulin, which exerts its anabolic action by reducing proteolysis.
Asunto(s)
Factor I del Crecimiento Similar a la Insulina/farmacología , Leucina/metabolismo , Biosíntesis de Proteínas , Adulto , Humanos , Insulina/sangre , Insulina/farmacología , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Persona de Mediana Edad , Valores de ReferenciaRESUMEN
OBJECTIVE: Results from studies on the effect of glucocorticosteroids on protein turnover in both rat and man have been conflicting. The aim of this study was to investigate the primary cause of muscle wasting in patients with Cushing's syndrome. DESIGN: Studies of whole body 1(-14)C-leucine turnover in patients with Cushing's syndrome before and after successful treatment, and in control subjects. PATIENTS: Eleven patients with Cushing's syndrome before and after (n = 5) treatment and 11 control subjects. MEASUREMENTS: Whole body 1(-14)C-leucine turnover to determine leucine metabolic clearance rate, leucine production rate, leucine oxidation rate and leucine incorporation into protein. RESULTS: Plasma leucine concentration (mean +/- SEM 100 +/- 6 mumol/l), leucine metabolic clearance rate (9.97 +/- 0.11 mumol/min/kg), leucine turnover (0.98 +/- 0.11 mumol/min/kg) and leucine incorporation into protein (0.71 +/- 0.09 mumol/min/kg) were all significantly reduced in patients with Cushing's syndrome compared with control subjects (122 +/- 6 mumol/l, P < 0.05; 13.61 +/- 1.27 mumol/min/kg, P < 0.05; 1.65 +/- 0.12 mumol/min/kg, P < 0.05; 1.46 +/- 0.10 mumol/min/kg, P < 0.001, respectively). Leucine oxidation rate was similar in the patients with Cushing's syndrome and control subjects. When leucine metabolism was expressed in terms of lean body mass (LBM) in five patients with Cushing's syndrome and 11 control subjects, leucine MCR, leucine turnover and leucine oxidation were not significantly different in the two groups. However, leucine incorporation into protein was significantly reduced (P < 0.001) in the patients with Cushing's syndrome (1.07 +/- 0.20 mumol/min/kg LBM) compared with control subjects (1.95 +/- 0.11 mumol/min/kg LBM). CONCLUSION: We conclude from these studies that the muscle wasting associated with Cushing's syndrome is primarily due to a reduction in protein synthesis.
Asunto(s)
Síndrome de Cushing/metabolismo , Leucina/metabolismo , Músculos/metabolismo , Adulto , Anciano , Síndrome de Cushing/terapia , Femenino , Humanos , Leucina/biosíntesis , Leucina/farmacocinética , Masculino , Tasa de Depuración Metabólica/fisiología , Persona de Mediana Edad , Biosíntesis de ProteínasRESUMEN
The effects of growth hormone (GH) treatment on protein metabolism were studied in adults with GH deficiency (GHD). A double-blind, placebo-controlled trial of recombinant human GH, 0.018 IU/kg/day for 1 month followed by 0.036 IU/kg/day for 1 month, was performed with isotopic whole-body protein turnover studies at 0 and 2 months. In all, 18 adults with GHD (9 men, 9 women; mean age, 46.6 years; range, 30-56 years) were studied. Whole-body isotopic leucine turnover using L-[1-13C]leucine was assessed by measuring leucine Ra (a measure of protein degradation), non-oxidative leucine Rd (a measure of protein synthesis) and leucine oxidation rate. Lean body mass and circulating insulin-like growth factor I were significantly (p < 0.02) increased at 2 months in the GH-treated group, but not in the placebo group. There was no change in leucine Ra in either the placebo or GH-treated groups at 2 months. Leucine oxidation decreased (p < 0.01) and non-oxidative leucine Rd increased (p < 0.02) in the GH-treated group at 2 months. There was no significant change in either leucine oxidation or non-oxidative leucine Rd in the placebo group at 2 months. These results indicate that the increase in lean body mass resulting from GH treatment in adults with GHD is due to an increase in protein synthesis.
Asunto(s)
Hormona del Crecimiento/deficiencia , Hormona del Crecimiento/uso terapéutico , Hipopituitarismo/tratamiento farmacológico , Proteínas/metabolismo , Adulto , Método Doble Ciego , Femenino , Humanos , Hipopituitarismo/metabolismo , Leucina/metabolismo , Masculino , Persona de Mediana Edad , Proteínas/efectos de los fármacos , Proteínas Recombinantes/uso terapéuticoRESUMEN
OBJECTIVE: Growth hormone treatment given to adult growth hormone deficient patients leads to an increase in lean body mass by an unknown mechanism. The aim of this study was to investigate the actions of growth hormone treatment on protein metabolism in adult growth hormone deficient patients. DESIGN: Double-blind, placebo controlled trial of recombinant human growth hormone (0.018 U/kg/day for 1 month followed by 0.036 U/kg/day for 1 month) with isotopic whole body protein turnover studies at 0 and 2 months. PATIENTS: Eighteen adult growth hormone deficient patients (nine male, nine female of mean age 46.6 (range 30-56). MEASUREMENTS: Whole body isotopic leucine turnover using L-1-13C-leucine measuring leucine Ra (a measure of protein degradation), non-oxidative leucine Rd (a measure of protein synthesis) and leucine oxidation rate. RESULTS: Lean body mass (P < 0.02), circulating insulin-like growth factor I (P < 0.01) and insulin (P < 0.02) were significantly increased at 2 months in the treatment group but there was no change in the placebo group. When expressed in relation to body weight, leucine Ra and non-oxidative leucine Rd increased (P < 0.01) and leucine oxidation decreased (P < 0.02) after 2 months growth hormone treatment. When expressed in relation to lean body mass non-oxidative leucine Rd increased (P < 0.02) and leucine oxidation decreased (P < 0.02) but there was no significant change in leucine Ra after 2 months growth hormone treatment. In the placebo group there were no significant changes in leucine metabolism expressed as lean body mass or body weight after 2 months. changes in leucine metabolism expressed as lean body mass or body weight after 2 months. CONCLUSION: These results indicate that the increase in lean body mass resulting from growth hormone treatment in adult growth hormone deficient patients is due to an increase in protein synthesis.
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Trastornos del Crecimiento/tratamiento farmacológico , Hormona del Crecimiento/uso terapéutico , Proteínas/metabolismo , Adulto , Peso Corporal/efectos de los fármacos , Método Doble Ciego , Femenino , Trastornos del Crecimiento/metabolismo , Hormona del Crecimiento/metabolismo , Humanos , Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leucina/metabolismo , Masculino , Persona de Mediana Edad , Proteínas Recombinantes/uso terapéuticoRESUMEN
Glucose intolerance, sometimes severe enough to cause frank diabetes mellitus, is a frequent feature of Cushing's syndrome. The primary cause of the hyperglycaemia, whether due to glucose over-production or under-utilization, remains unresolved. We therefore measured glucose turnover using an intravenous bolus of 3-3H glucose in 14 normoglycaemic patients with Cushing's syndrome and 14 control subjects. Seven of the patients with Cushing's syndrome were also restudied post-operatively. Plasma glucose concentrations were similar in all three groups whereas glucose metabolic clearance rate (MCR) (1.80 +/- 0.06 ml/min/kg) and glucose turnover rate (9.09 +/- 0.36 mumol/min/kg) were significantly reduced in patients with Cushing's syndrome compared to normal subjects (2.21 +/- 0.1; P less than 0.001; 10.90 +/- 0.50; P less than 0.01) and rose post-operatively to normal values (2.35 +/- 0.14 ml/min/kg; 11.07 +/- 0.48 mumol/min/kg). We conclude from these results that the hyperglycaemia sometimes found in Cushing's syndrome may be primarily due to decreased utilization rather than increased glucose production.
Asunto(s)
Síndrome de Cushing/metabolismo , Glucosa/metabolismo , Adrenalectomía , Adulto , Anciano , Glucemia/metabolismo , Síndrome de Cushing/cirugía , Femenino , Glucosa/administración & dosificación , Humanos , Hipofisectomía , Inyecciones Intravenosas , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Periodo PosoperatorioRESUMEN
2-Deoxyglucose uptake (3 min) and 3-O-methylglucose transport (2 s) was measured in rat adipocytes preincubated with 5 microM epinephrine plus adenosine deaminase as described by Green (Green, A. (1983) FEBS Lett. 152, 261-264). 2-Deoxyglucose uptake was about 95% depressed in insulin-treated, but not in 'basal', cells preincubated with epinephrine plus adenosine deaminase for 60 min in broad agreement with Green's report. However, this depression was caused by a decrease in sugar phosphorylation rather than transport. In similarly incubated cells, transport of 3-O-methylglucose, a sugar analogue not phosphorylated in the adipocytes, was not affected by catecholamine plus adenosine deaminase. However, a decrease in transport of about 60% was observed both in the absence and the presence of insulin when the albumin concentration was high enough and the cell concentration low enough to prevent accumulation of free fatty acids in the medium. In addition, the insulin sensitivity with regard to hexose transport was markedly reduced. Transport was approximately doubled in cells incubated with 5 microM epinephrine in the absence of adenosine deaminase. Thus, epinephrine at a high concentration stimulates hexose transport in the absence of adenosine deaminase (presence of adenosine) whereas it inhibits both basal and insulin-stimulated transport in the presence of adenosine deaminase (absence of adenosine).