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H Beck-Nielsen

Publications and source records attributed to H Beck-Nielsen.

At least 37 records · Page 2Linked to original sources
PubMed2002

Regenerating human muscle fibres express GLUT3 protein.

The presence of the GLUT3 glucose transporter protein in human muscle cells is a matter of debate. The present study was designed to establish whether GLUT3 is expressed in mature human skeletal muscle fibres and, if so, whether its expression changes under different conditions, such as metabolic stress (obesity, obese non-insulin-dependent diabetes mellitus), hypertrophy (training), de- and reinnervation (amyotrophic lateral sclerosis) or regeneration (polymyositis). We used an immunohistochemical approach to detect and localise GLUT3. GLUT3 immunoreactivity was not detectable in adult skeletal muscle fibres, nor did metabolic stress, training or de- and re-innervation induce GLUT3 expression, while a few GLUT3 expressing fibres were seen in some cases of polymyositis. In contrast, GLUT4 was expressed in all investigated muscle fibres. GLUT3 immunoreactivity was found in perineural and endoneural cells, indicating that GLUT3 is important for glucose transport into nerves through the perineurium. Taken together, these data suggest that GLUT3 expression is restricted to regenerating muscle fibres and nerves in adult human muscle. Although the significance of GLUT3 in adult human muscle fibres appears limited, GLUT3 may be of importance for the glucose supply in fetal muscle fibres and regenerating adult muscle fibres.

Adult↗
PubMed2002

Insulin signalling in skeletal muscle of subjects with or without Type II-diabetes and first degree relatives of patients with the disease.

AIMS/HYPOTHESIS: Alterations in insulin signalling could contribute to insulin resistance in Type II (non-insulin-dependent) diabetes mellitus. Some of these alterations could be secondary to the diabetic state, ie. the hyperglycaemia or increased NEFA concentrations. We sought to exclude such secondary factors and to investigate whether Type II diabetes in itself is associated with altered insulin signalling in skeletal muscle. METHODS: Hyperinsulinaemic-euglycaemic clamps were performed in 10 obese Type II diabetic patients whose glucose concentrations had been normalised for 8 h by plasma glucose-adapted insulin infusion, 10 BMI-matched first-degree relatives of Type II diabetic patients, and 10 BMI-matched non-diabetic subjects. Muscle biopsies were obtained before and at the end of the clamps, and insulin receptor kinase activity, phosphatidylinositol-3'-kinase activity, Akt-Thr(308)-phosphorylation, and glycogen synthase activity determined. RESULTS: At similar steady-state clamp insulin concentrations (approximately 400 pmol/l) similar receptor kinase activities, phosphatidylinositol-3'-kinase activities, Akt-Thr(308)-phosphorylation, and glycogen synthase activities were found in all subject groups although glucose disposal was reduced in the diabetic subjects and relatives. Pre-clamp signalling levels were different between subject groups, most likely due to different pre-clamp insulin concentrations. CONCLUSION/INTERPRETATION: Our results in subjects at risk for the development of diabetes and Type II diabetic patients with normalized glucose concentrations suggest that Type II diabetes in itself is not associated with reduced signalling intensity at the studied signalling molecules, at least not at the chosen clamp insulin concentration and under the chosen conditions. Alterations responsible for the reduced glucose disposal could be located downstream of the investigated steps or in alternative insulin signalling pathways. A different spatial organisation of the investigated signalling molecules can also not be excluded.

Adult↗
PubMed2002

GLUT4 expression at the plasma membrane is related to fibre volume in human skeletal muscle fibres.

In this study we examined the relationship between GLUT4 expression at the plasma membrane and muscle fibre size in fibre-typed human muscle fibres by immunocytochemistry and morphometry in order to gain further insight into the regulation of GLUT4 expression. At the site of the plasma membrane, GLUT4 was more abundantly expressed in slow as compared to fast fibres at the same fibre diameter (p < 0.01) and the GLUT4 expression increased with increasing fibre radius independently of fibre type (p < 0.01). The GLUT4 density at the surface of slow fibres of both diabetic and obese was reduced compared to control subjects at the same diameter (p < 0.001). Fast fibres in obese and type 2 diabetic subjects expressed a fibre-volume-dependent GLUT4 expression (p < 0.001), while this did not reach significance in slow fibres (obese p = 0.18 and diabetic p = 0.06). Our results show that increasing fibre volume is associated with increasing GLUT4 expression in both slow and fast fibres. Based on the possible dependency of GLUT4 expression on volume, we hypothesize that the reduced GLUT4 expression in obesity and type 2 diabetes may partly be compensated for by physical activity.

Adult↗
PubMed2002

The influence of the polymorphism in apolipoprotein B codon 2488 on insulin and lipid levels in a Danish twin population.

AIMS: The apolipoprotein B codon 2488 polymorphism has been associated with the metabolism of lipoproteins in subjects with Type 2 diabetes. However, no data are available on the influence of the polymorphism on insulin or glucose metabolism. This study examines the impact of the polymorphism on parameters associated with the insulin resistance syndrome in Danish twins. METHODS: The effect of the polymorphism on lipid, glucose and insulin measures was studied in 548 same sex twins aged 55-74 years. RESULTS: The codon 2488 polymorphism influenced fasting triglyceride levels, as well as insulin, as measured at 120 min in an oral glucose tolerance test. Subjects with the genotype T2488T had 14% higher triglyceride levels (P = 0.02) and 31% higher insulin levels (P = 0.004) than subjects with genotype C2488C. In twins discordant for genotype, the T-allele was associated with higher levels of triglyceride (P = 0.04) and insulin (P = 0.02) and lower levels of HDL-cholesterol (P = 0.04). CONCLUSION: The T-allele of the codon 2488 polymorphism influenced parameters related to the insulin resistance syndrome, i.e. increased levels of insulin, increased levels of triglyceride and decreased levels of HDL. As the polymorphism is silent, these effects must be mediated through linkage to other polymorphisms in apolipoprotein B or other genes on chromosome 2.

Aged↗
PubMed2002

Effect of insulin on protein phosphatase 2A expression in muscle in type 2 diabetes.

BACKGROUND: Protein phosphatase 2A (PP2A) acts on a number of enzymes involved in the insulin regulation of glucose uptake and glycogen synthesis. This study was carried out to investigate the effect of insulin on PP2A expression in skeletal muscles of type 2 diabetic and control subjects. MATERIAL AND METHODS: Ten type 2 diabetic and 10 matched, control subjects were studied using the euglycaemic-hyperinsulinaemic clamp technique combined with indirect calorimetry. Immunoreactive protein levels of the catalytic alpha subunit of PP2A (PP2A-C alpha) were measured in biopsies from the vastus lateralis muscle obtained in the basal and insulin-stimulated state. RESULTS: In type 2 diabetic subjects insulin-mediated glucose disposal, glucose oxidation and nonoxidative glucose metabolism were reduced, whereas lipid oxidation was increased (all P < 0.05). Insulin down-regulated PP2A-C alpha expression in skeletal muscle of the control subjects (P < 0.05) but not in the type 2 diabetic subjects. In the control subjects, the insulin-mediated decrease in PP2A-C alpha correlated with the insulin-mediated increase in glucose disposal, glucose oxidation, nonoxidative glucose metabolism (all P < 0.05) and decrease in lipid oxidation (P < 0.01). In the type 2 diabetic subjects these relationships were absent. CONCLUSIONS: Down-regulation of PP2A-C alpha expression by insulin in skeletal muscle seems to be associated with a normal insulin action on glucose storage, glucose and lipid oxidation. Impaired down-regulation of PP2A-C alpha expression by insulin may be a marker for insulin resistance and contribute to the pathogenesis of type 2 diabetes.

Biomarkers↗
PubMed2002

Is low birth weight a risk factor for the development of diabetic nephropathy in patients with type 1 diabetes? A population-based case-control study.

OBJECTIVES: To investigate if low birth weight as a consequence of intrauterine malnutrition is a risk factor for the later development of diabetic nephropathy. DESIGN AND SUBJECTS: In a case-control set-up a group of type 1 diabetic subjects with diabetic nephropathy (n = 51) and a matched control group with normal kidney function (n = 51) were compared. Diabetic nephropathy and normal kidney function were defined as urinary albumin excretion rate above 200 microg min-1 and below 20 microg min-1, respectively. The birth weights were all obtained from the midwives' original records. SETTING: The patients were identified from a population-based study of chronic diabetic complications in the Funen County, Denmark. MAIN OUTCOMES: Birth weights according to the presence of diabetic nephropathy. RESULTS: The median (10-90 percentile) birth weights were 3,600 g (2,960-4,274) in the group with diabetic nephropathy and 3,600 g (2,880-4,220) in the group without nephropathy, P = 0.52. In the lower quartile of birth weights the median (10-90 percentile) birth weights were 3,000 g (2,780-3,200) in the group with nephropathy versus 2,850 g (2,250-3,175) in the group without nephropathy, P = 0.07. In the upper quartile the median (10-90 percentile) birth weights were 4,225 g (4,000-4,741) in the nephropathy group and 4,000 g in the group without nephropathy, P = 0.13. We found no significant correlation between birth weights and log urinary albumin excretion rate (r = 0.148, P = 0.14) and no difference in the number of patients with nephropathy in the lower versus upper quartiles of birth weights. CONCLUSION: We found no evidence of low birth weight as a risk factor for the development of diabetic nephropathy.

Adolescent↗
PubMed2002

Delays in insulin signaling towards glucose disposal in human skeletal muscle.

We explored whether the delay that occurs between a rise in plasma insulin and the increase of glucose disposal occurs before, at, or downstream of steps that are believed to be part of the insulin signaling cascade. Skeletal muscle biopsies were obtained from 16 nondiabetic subjects before, and 20 and 180 min after plasma insulin levels had been augmented in euglycemic hyperinsulinemic glucose clamps. Although plasma insulin had reached 98% of its final concentration within 10 min, insulin receptor kinase (IRK) activity, p85 associated with insulin receptor substrate-1 (IRS-1), IRS-1-associated phosphatidylinositol 3-kinase (PI3K) activity, and Thr(308)-protein kinase B (PKB) phosphorylation in the muscle biopsies at 20 min had reached only 60, 48, 34 and 47% respectively of those at 180 min. This suggests a delay before the level of IRK and little or no delay between IRK and PKB activation. The observation that glycogen synthase activity and glucose disposal at 20 min had both only reached 25% of the respective values at 180 min suggests an additional delay downstream of the investigated signaling steps.

Analysis of Variance↗
PubMed2001

[Hormone replacement therapy reduces the risk of forearm fracture in postmenopausal women. Results of the Danish Osteoporosis Prevention Study].

In a prospective, controlled, comprehensive cohort trial of 2,016 healthy early postmenopausal women aged 45-58 years we studied fracture prevention through the use of oestrogen. There were two main study arms: a randomised arm (randomised to HRT [n = 502] or not [n = 504]) and a non-randomised arm (on HRT [n = 221] or not [n = 789] by own choice). After five years, an intention-to-treat analysis (n = 2,016) showed a reduction in the overall fracture risk (RR = 0.73, 95% CI: 0.50-1.05) and in the forearm fracture risk (RR = 0.45, 95% CI: 0.22-0.90) with oestrogen. Restriction of the analysis to women who had adhered to their initial allocation of either oestrogen (n = 395) or no oestrogen (n = 977) showed a significant reduction in both the overall fracture risk (RR = 0.61, 95% CI: 0.39-0.97) and the risk of forearm fractures (RR = 0.24, 95% CI: 0.09-0.69). We conclude that it is possible to reduce the number of forearm fractures in early postmenopausal women by the use of oestrogen as primary prevention.

Aged↗
PubMed2001

The basal kinetic parameters of glycogen synthase in human myotube cultures are not affected by chronic high insulin exposure.

There is no consensus regarding the results from in vivo and in vitro studies on the impact of chronic high insulin and/or high glucose exposure on acute insulin stimulation of glycogen synthase (GS) kinetic parameters in human skeletal muscle. The aim of this study was to evaluate the kinetic parameters of glycogen synthase activity in human myotube cultures at conditions of chronic high insulin combined or not with high glucose exposure, before and after a subsequent acute insulin stimulation. Acute insulin stimulation significantly increased the fractional activity (FV(0.1)) of GS, increased the sensitivity of GS to the allosteric activator glucose 6-phosphate (A(0.5)) and increased the sensitivity of GS to its substrate UDPG (K(m(0.1))) when myotubes were precultured at low insulin with/without high glucose conditions. However, this effect of acute insulin stimulation was abolished in myotubes precultured at high insulin with or without high glucose. Furthermore, we found significant correlations between the fractional velocities FV(0.1) of GS and K(m(0.1)) (rho=-0.72, P<0.0001), between FV(0.1) and A(0.5) (rho=-0.82, P<0.0001) and between K(m(0.1)) and A(0.5) values (rho=0.71, P<0.0001). Our results show that chronic exposure of human myotubes to high insulin with or without high glucose did not affect the basal kinetic parameters but abolished the reactivity of GS to acute insulin stimulation. We suggest that insulin induced insulin resistance of GS is caused by a failure of acute insulin stimulation to decrease A(0.5) and K(m(0.1)) in human skeletal muscle.

Biopsy↗
PubMed2001

[Thiazolidinediones--a new class of oral antidiabetics].

Two members of the group, thiazolidinediones, have been approved for the treatment of type 2 diabetes mellitus. These novel oral antihyperglycaemic agents reduce insulin resistance through binding to and activation of the nuclear receptor, PPAR gamma, with subsequent effects on the glucose and lipid homoeostasis. The compounds will probably exhibit beneficial effects on other facets of the metabolic syndrome. Their effectiveness on glycaemic control appears comparable, as assessed by the literature available. HbA1c is lowered by 1.0 to 1.5%. Both drugs are approved for combination therapy with either metformin or sulphonylureas, not as monotherapy or in combination with insulin. Disturbed heart function (NYHA I-IV) is a contra-indication. In contrast to troglitazone, there is so far no evidence of liver toxicity. In spite of the limited literature, it is anticipated that the present class of oral hypoglycaemic agents will turn out to be an important contribution to improving the metabolic control of patients with type 2 diabetes, if the safety profile remains unchanged in long-term studies.

Administration, Oral↗
PubMed2001

[Randomized controlled trial of structured, individualized treatment of type 2 diabetes mellitus. The project of Diabetes Care in General Practice].

INTRODUCTION: We assessed the effect of a multifaceted intervention directed at general practitioners to improve type 2 diabetes care. MATERIALS AND METHODS: Three hundred and eleven Danish practices with 474 general practitioners were randomised to structured personal care (intervention group) or routine care (comparison group). Of 970 surviving patients (aged 40+ years) diagnosed with diabetes in 1989-1991, 874 (90.1%) were assessed after 6 years. Intervention comprised regular follow-up and individualized goal-setting, supported by reminders to doctors, clinical guidelines, feed-back, and continuing medical education. RESULTS: Predefined non-fatal outcomes and mortality were the same in both groups. The following risk factor levels were lower in the intervention patients than in the comparison patients: fasting plasma glucose (7.9 vs 8.7 mmol/l, medians, P = 0.0007), haemoglobin A1c (8.5 vs 9.0%, P < 0.0001, normal range 5.4-7.4%), systolic blood pressure (145 vs 150 mmHg, P = 0.0004), and cholesterols (6.0 vs 6.1 mmol/l, P = 0.029, baseline-adjusted). Both groups had sustained a weight loss since diagnosis (2.6 vs 2.0 kg). Metformin was the only drug used more frequently in the intervention group (24 vs 15%). Intervention doctors arranged more follow-up consultations, referred fewer patients to diabetes clinics, and were more optimistic in their goal-setting. DISCUSSION: In primary care, individualized goal-setting with educational and surveillance support may for at least six years bring risk factors of patients with type 2 diabetes to a level that in other trials has been shown to reduce diabetic complications, but without adverse weight gain.

Denmark↗
PubMed2001

Randomised controlled trial of structured personal care of type 2 diabetes mellitus.

OBJECTIVE: To assess the effect of a multifaceted intervention directed at general practitioners on six year mortality, morbidity, and risk factors of patients with newly diagnosed type 2 diabetes. DESIGN: Pragmatic, open, controlled trial with randomisation of practices to structured personal care or routine care; analysis after 6 years. SETTING: 311 Danish practices with 474 general practitioners (243 in intervention group and 231 in comparison group). PARTICIPANTS: 874 (90.1%) of 970 patients aged >/=40 years who had diabetes diagnosed in 1989-91 and survived until six year follow up. INTERVENTION: Regular follow up and individualised goal setting supported by prompting of doctors, clinical guidelines, feedback, and continuing medical education. MAIN OUTCOME MEASURES: Predefined clinical non-fatal outcomes, overall mortality, risk factors, and weight. RESULTS: Predefined non-fatal outcomes and mortality were the same in both groups. The following risk factor levels were lower for intervention patients than for comparison patients (median values): fasting plasma glucose concentration (7.9 v 8.7 mmol/l, P=0.0007), glycated haemoglobin (8.5% v 9.0%, P<0.0001; reference range 5.4-7.4%), systolic blood pressure (145 v 150 mm Hg, P=0.0004), and cholesterol concentration (6.0 v 6.1 mmol/l, P=0.029, adjusted for baseline concentration). Both groups had lost weight since diagnosis (2.6 v 2.0 kg). Metformin was the only drug used more frequently in the intervention group (24% (110/459) v 15% (61/415)). Intervention doctors arranged more follow up consultations, referred fewer patients to diabetes clinics, and set more optimistic goals. CONCLUSIONS: In primary care, individualised goals with educational and surveillance support may for at least six years bring risk factors of patients with type 2 diabetes to a level that has been shown to reduce diabetic complications but without weight gain.

Age Factors↗
PubMed2001

Genetic versus environmental aetiology of the metabolic syndrome among male and female twins.

AIMS/HYPOTHESIS: The aetiology of the metabolic syndrome including hyperinsulinaemia, glucose intolerance, dyslipidaemia, hypertension and obesity is not known. We studied the relative impact of genetic versus environmental factors for the development of the components in the syndrome among male and female twins. METHODS: A total of 303 elderly twin pairs participated in the study. We report concordances and heritability estimates of the components by classic twin analysis to assess the proportion of variation attributed to genetic factors. RESULTS: All components correlated significantly. The concordance rates for glucose intolerance, overall obesity and low HDL-cholesterol were significantly higher among monozygotic than dizygotic twins indicating a genetic influence on the development of these phenotypes. The heritability estimates for glucose concentration, BMI and HDL-cholesterol among monozygotic twins confirmed these findings. The heritability estimates for waist-to-hip ratio, fasting insulin and triglycerides, however, were low, indicating a major environmental influence. We found a higher genetic influence on glucose intolerance and systolic blood pressure and a lower genetic influence on low HDL-cholesterol and diastolic blood pressure among male twins compared to female twins. CONCLUSION/INTERPRETATION: Based on the correlations between the components in the syndrome, we propose a core complex including hyperinsulinaemia, obesity, hypertriglyceridaemia and low HDL-cholesterol with only weak associations to glucose concentrations and blood pressure levels. The study confirms the notion of a multifactorial aetiology of the components including genetic and non-genetic factors. The differences in aetiology between male and female twins indicate an influence of sex on several of the components in the metabolic syndrome.

Aged↗
PubMed2001

Morphometric documentation of abnormal intramyocellular fat storage and reduced glycogen in obese patients with Type II diabetes.

AIMS/HYPOTHESIS: Insulin resistance of skeletal muscle has been associated with increased lipid availability. This study aimed to estimate volume fractions of intramyocellular triglyceride droplets and glycogen granules in skeletal muscle using electron microscopy and furthermore, relate these findings to insulin sensitivity and the level of circulating lipids. METHODS: We compared 11 obese patients with Type II (non-insulin-dependent) diabetes mellitus and 11 obese normoglycaemic subjects matched for age and sex. Glucose metabolism was determined using the euglycaemic hyperinsulinaemic clamp technique (40 mU.m(-2).min(-1)) coupled with indirect calorimetry and tritiated glucose. On the second day, using an automatic procedure, a fasting muscle biopsy was carried out and processed for electron microscopy. Volume fractions of intramyocellular structures were estimated by pointcounting on photographic pictures in a blinded manner. RESULTS: Insulin-stimulated total glucose disposal rate was lower in the Type II diabetic subjects compared with the obese normoglycaemic subjects (4.96 +/- 049 vs 10.35 +/- 0.89 mg.min(-1).kg ffm(-1), p < 0.001) as was glucose storage (2.03 +/- 0.50 vs 6.59 +/- 0.83, p < 0.001). The electron microscopy study revealed that the diabetic subjects had higher intramyocellular amounts of triglyceride (1.43 +/- 0.21 vs 0.39 +/- 0.07%, p < 0.001) and lower amounts of glycogen (3.53 +/- 0.33 vs 6.94 +/- 0.54%, p < 0.001). Mitochondrial volume was identical indicating equal aerobic capacity. The fractional intramyocellular lipid volume was found to be positively associated with fasting NEFA (r = 0.63, p = < 0.05 and r = 0.79, p = < 0.05) and triglyceride (r = 0.74, p = 0.01 and r = 0.62, p < 0.05) in the obese diabetic and normoglycaemic cohorts respectively. Intramyocellular lipid content was negatively correlated to insulin sensitivity (r = -0.71, p < 0.02) in the obese diabetic group whereas no significant association was found in the obese normoglycaemic group. CONCLUSION/INTERPRETATION: This study shows that fat accumulates intramyocellulary while glycogen stores are simultaneously reduced in obese subjects with Type II (non-insulin-dependent) diabetes mellitus. Quantitatively, a major component of the excessive lipid accumulation could be secondary in origin, related to the diabetic state in itself, although a contribution from the altered insulin action cascade of obesity and diabetes cannot be excluded. In both groups significant positive relations were found between circulating and intramyocellular lipid.

Adipocytes↗
PubMed2001

The GLUT4 density in slow fibres is not increased in athletes. How does training increase the GLUT4 pool originating from slow fibres?

The influence of training on GLUT4 expression in slow- and fast-twitch skeletal muscle fibres was studied in male endurance-trained athletes and control subjects. The trained state was ensured by elevated maximal oxygen uptake (29%), as well as citrate synthase (60%) and 3-hydroxy-acyl-CoA dehydrogenase (38%) activities in muscle biopsy samples of the vastus lateralis. GLUT4 densities in slow- and fast-twitch fibres were measured by the use of a newly developed, sensitive method combining immunohistochemistry with morphometry, and no effect of training was found. GLUT4 density was higher in slow-twitch fibres compared to fast-twitch fibres (P<0.05) when biopsy samples from untrained subjects were examined. In athletes GLUT4 density was identical in slow- and fast-twitch fibres. Slow-twitch fibre diameters were 10% larger in the athletes (P<0.01), and slow-twitch fibre fractions were 140% of the fraction in the control group. Thus, GLUT4 originating from slow-twitch fibres was increased by 30% (P<0.02) in athletes. We conclude that long-lasting endurance training increases slow-twitch fibre GLUT4 expression by means of an elevated slow-twitch fibre mass in human skeletal muscle.

Adult↗
PubMed2001

Proliferation conditions for human satellite cells. The fractional content of satellite cells.

Primary satellite cell cultures have become an important tool as a model system for skeletal muscles. A common problem in human satellite cell culturing is fibroblast overgrowth. We combined N-CAM (Leu19) immunocytochemical staining of satellite cells (Sc) with stereological methods to estimate the fraction of Sc in culture. Evaluation of different culture conditions allowed us to find proliferation conditions preferentially for Sc: a) Sc should be cultured on surfaces coated with ECM-gel. b) Primary cell culture should be inoculated in DMEM supplemented with 10% fetal calf serum to increase cell adherence. c) Change of media to DMEM supplemented with 2% Ultroser-G and 2% FCS after 24 h.d) Before subcultivation, cells should be preplated for 30 min. The fractional content of Sc in passage four when applying this method of cultivation was 0.82 +/- 0.07 (mean +/- SE, N = 10). Our method enabled us to establish culture conditions which resulted in high Sc content despite several subcultivations. Estimation of the fractional cell content could be a useful tool for optimizing not only Sc-culturing but all cultures initially containing more cell types.

Cell Culture Techniques↗
PubMed2001

A cellular model system of differentiated human myotubes.

The aim of this study was to select an effective and stable protocol for the differentiation of human satellite cells (Sc) and to identify the optimal time period for the experimental use of differentiated human Sc-cultures. In order to identify the differentiation conditions which give a good survival of myotubes and a high grade of differentiation, Sc-cultures were induced to differentiate in media supplemented with either 2% fetal calf serum (FCS) 2% horse serum (HS) or 10% HS. Based on higher CK-activities in cultures differentiating in FCS-supplemented media compared to horse sera, fetal calf serum was chosen to induce differentiation. The ATP, DNA and protein content increased during the first 4 days after induction of differentiation and was followed by a period with minor changes. The maximal differences of ATP, DNA and protein between days 4-10 were evaluated and the differences in the three components were found to be less than 20% of the average value with a certainity of more than 0.9. Day 8-myotubes were investigated morphologically and were found immunoreactive for fast myosin, and expressed areas with clear cross striation. We recommend the use of differentiated Sc-cultures in the period from day 4 to 8 after induction of differentiation as only minor differentation-related changes will take place in the cells during this period of time.

Adenosine Triphosphate↗