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At least 19 recordsLinked to original sources
PubMed1978

Musle protein breakdown rates in humans based on Ntau-methylhistidine (3-methylhistidine) content of mixed proteins in skeletal muscle and urinary output of Ntau-methylhistidine.

Samples of psoas muscle from nine infants (aged 1 day to 14 mo) and of several skeletal muscles from seven adult males (age 19-74 yr) were analyzed for content of protein-bound Ntau-methylhistidine (3-methylhistidine; 3-Mehis). The mean content of 3-Mehis (expressed as mumoles/g mixed protein) was 3.2 (range 2.4-3.7) in infants and 4.2 (range 3.7-4.6) in adults. The daily urinary excretion of 3-Mehis was measured in four young adult males receiving an egg-protein, flesh-free diet. Mean excretion of 3-Mehis was 211 (range 167-252) mumoles/day. From these two sets of data the mean rate of muscle protein breakdown in adult males was estimated to be 50 g/day, or 0.7 +/- 0.1 g/kg body weight/day. These results are compared with reported values for the 3-Mehis content of mixed proteins in muscle of various species, and with published estimates, computed by other techniques, of the rate of muscle protein breakdown in human subjects.

Adult↗
PubMed1983

3-Methylhistidine turnover in the whole body, and the contribution of skeletal muscle and intestine to urinary 3-methylhistidine excretion in the adult rat.

The tissue origin of 3-methylhistidine (N tau-methylhistidine) was investigated in adult female rats. The decay of labelling of urinary 3-methylhistidine was compared with the labelling of protein-bound 3-methylhistidine in skeletal muscle and intestine after the injection of [methyl-14C]methionine. The decay curve for urinary 3-methylhistidine was much steeper than that in muscle or intestine, falling to values lower than those in either tissue after 30 days. The lack of decay of labelling in muscle during the first 30 days is shown to result from the persistence of label in the precursor S-adenosylmethionine. The relative labelling of urinary, skeletal-muscle and intestinal 3-methylhistidine cannot be explained in terms of skeletal muscle accounting for a major proportion of urinary 3-methylhistidine. Measurements were also made of the steady-state synthesis rate of protein-bound 3-methylhistidine in intestinal smooth muscle in vivo in adult female rats. This involved measurement of the overall rate of protein synthesis and measurement of the relative rates of synthesis of 3-methylhistidine and of mixed protein. The synthesis rate of 3-methylhistidine was 29.1%/day, compared with the overall rate of 77.1%/day for mixed, non-mucosal intestinal protein. Measurement of the amount of 3-methylhistidine in skeletal muscle (0.632 +/- 0.024 mumol/g) and in the whole body (0.332 +/- 0.013 mumol/g) indicate that, although the muscle pool is 86% of the total, because of its slow turnover rate of 1.1-1.6%/day, it only accounts for 38-52% of the observed excretion. Measurements of the mass of the intestine (9.95 g/250 g body wt.) and protein-bound 3-methylhistidine content (0.160 mumol/g of tissue) indicate a pool size of 1.59 mumol/250 micrograms rat. Thus 463 nmol of the urinary excretion/day would originate from the intestine, 22% of the total. The tissue source of the remaining urinary excretion is not identified, but other non-muscle sources constituting about 10% of the whole-body pool could account for this with turnover rates of only 6%/day, a much lower value than the turnover rate in the intestine.

Animals↗
PubMed1987

The retention and metabolism of N tau-methylhistidine by cockerels: implications for the measurement of muscle protein breakdown determined from the excretion of N tau-methylhistidine in excreta.

Excreta were collected for four consecutive days from 4- to 18-week-old cockerels following subcutaneous injection of N tau-[14CH3]methylhistidine. The recoveries of radioactivity in excreta were incomplete and progressively decreased with increasing age. Most of the radioactivity not recovered in excreta after 4 d was found in skeletal muscle where greater than 55% of the radioactivity present was in the N tau-methylhistidine-containing dipeptide, balenine. This peptide appeared to be relatively stable so that most of the labelled N tau-methylhistidine incorporated was not released during the period of the recovery measurements. The total pool of non-protein bound N tau-methylhistidine (free (free N tau-methylhistidine + balenine) in pectoral and mixed thigh muscles increased with age and relative to the daily excretion of N tau-methylhistidine. At 18 weeks the pool was 3.3 times the daily excretion of N tau-methylhistidine. These observations account for the decreasing recoveries of radioactivity in excreta described previously, due to progressive dilution of labelled N tau-methylhistidine in an expanding pool of non-protein-bound N tau-methylhistidine, part of which was relatively stable. It is concluded that excretion of N tau-methylhistidine by 4- to 18-week-old cockerels cannot be used as a reliable index of muscle protein breakdown in vivo.

Age Factors↗
PubMed1987

Urinary excretion of 1-methylhistidine: a qualitative indicator of exogenous 3-methylhistidine and intake of meats from various sources.

In order to investigate whether the urinary excretion of 1-methylhistidine (1MH) might serve as an objective indicator of meat ingestion and exogenous 3-methylhistidine (3MH) intake, healthy subjects were fed an ovolactovegetarian diet. At five-day intervals they were given meat of different origin and 24-hour urinary excretions of 1MH and 3MH were determined. After beef intake there was a marked increase of 3MH and 1MH excretion. The elimination curves were found to follow first-order kinetics and to indicate similar elimination rates. 1MH was present in ten different types of meat analyzed. A strong linear relationship was found between increase in 3MH and 1MH excretion and the amount of chicken, pork, or plaice ingested. IMH may serve as an objective indicator of meat and exogenous 3MH intake, since it is present in meat, and, regardless of source, shows similar dose-independent kinetics, and has similar half-life to 3MH.

Adult↗
PubMed2005

Determination of 3-methylhistidine and 1-methylhistidine in untreated urine samples by capillary electrophoresis.

Capillary electrophoretic (CE) method was developed for the determination of urinary 3-methylhistidine (3MH) and 1-methylhistidine (1MH) indicating the extent of degradation of skeletal muscle proteins and thereby the state of human health. 3MH, 1MH and histidine can be separated in both acidic and alkaline media, where these amino acids form cation and anion, respectively. The effective mobility of all ionic forms was measured over a broad range of pH (1.67-11.80), which made it possible to evaluate the corresponding dissociation constants. 3MH and 1MH were determined together with creatinine in untreated urine samples with the limit of detection of 2.4 microM (0.4 mgL(-1)) and 3.0 microM (0.5 mgL(-1)), respectively. Determination was fast and took ca. 12 min including the column washing. Method was employed for an analysis of urine collected from healthy individuals, and from the patients hospitalized with obesity and diabetes mellitus II. This analysis has revealed differences between the healthy individuals and the patients pointing to a more extensive degradation of muscle proteins in the latter group.

Diabetes Mellitus↗
PubMed1997

High-performance liquid chromatographic determination of imidazole dipeptides, histidine, 1-methylhistidine and 3-methylhistidine in equine and camel muscle and individual muscle fibres.

The combined solid-phase extraction (Isolute PRS columns) and reversed-phase gradient HPLC method presented provides a sensitive, reproducible and selective quantification of carnosine, balenine, homocarnosine, histidine, 1-methylhistidine and 3-methylhistidine in equine and camel muscle and individual muscle fibres. Recoveries were 91-115%. Lower limits of detection were 0.005-0.010 mmol kg-1 dry muscle. The compounds were isolated from other physiological amino acids and small peptides and resolved within a single chromatographic run of 55 min. Concentrations of these compounds in equine myocardium, diaphragm, skeletal muscle, camel muscle and individual muscle fibres of both species are presented for the first time.

Animals↗
PubMed1977

Fractional flux rates of Nt-methylhistidine in skin and gastrointestine: the contribution of these tissues to urinary excretion of Nt-methylhistidine in the rat.

1. Fractional flux rates of Ntau-methylhistidine (3-methylhistidine; Me-His) of skin and gastrointestine were measured by administering [methyl-3H]methionine to rats. 2. The results showed that the contribution of these tissues to urinary excretion of Me-His was at least 16-6%. This means that when fractional catabolic rates of myosin and actin were estimated from urinary excretion of Me-His, the part of Me-His derived from skin and gastrointestine should not be neglected.

Animals↗
PubMed1989

Evaluation of urinary 3-methylhistidine excretion in infection by measurements of 1-methylhistidine and the creatinine ratios.

When 3-methylhistidine (3MH) excretion is used as an indicator of myofibrillar protein catabolism, there are restricting factors, such as meat intake, incorrect 24-h urine collections, and a large interindividual variation in basal excretion. 1-Methylhistidine (1MH) was previously suggested as an indicator of meat intake. We studied the basal urinary excretion of 1MH and whether this was influenced by infection and we compared the use of 3MH vs the 3MH:creatinine ratio (3MH:Cr) in detecting changes during infection. The basal excretion of 1MH was 84.9 mumol/24 h and its creatinine molar ratio (1MH:Cr) was 7.4 x 10(-3) with no change during infection. Because 1MH:Cr was significantly increased in 4 of 14 patients, their 3MH values were considered influenced by meat intake and thus discarded. Among the remaining 10 patients, 9 showed a significant individual increase in 3MH:Cr during infection compared with only 4 in 3MH. This was due to a higher precision in 3MH:Cr despite the concomitant significant increase in urinary creatinine excretion.

Adolescent↗
PubMed1978

Ntau-methylhistidine (3-methylhistidine) and muscle protein turnover: an overview.

Actin and myosin, the contractile proteins of skeletal muscle, are methylated following peptide bond synthesis, with production of Ntau-methylhistidine (3-methylhistidine, 3-MeHis). During intracellular breakdown of these proteins, the 3-MeHis is released and excreted in the urine. Studies on tissue distribution of 3-MeHis and on its qunatitative excretion following administration to rats and to man show that urinary output of this amino acid provides a reliable index of the rate of myofibrillar protein breakdown in the musculature of intact rats and human subjects. Estimates of the fractional rate of muscle protein breakdown based on 3-MeHis data are consistent with rates computed by other techniques. By this technique, it has been shown that the fractional rate of muscle protein breakdown is not significantly different in the elderly as compared with young adults. However, since muscle mass is less in the elderly, it makes a smaller contribution to whole body protein breakdown with aging in humans. Output of 3-MeHis diminishes in growing rats and obese human subjects with protein or energy restriction, though the initial response of myofibrillar protein breakdown in growing rats to protein and protein-energy restriction differs. Measurement of 3-MeHis excretion has also proved useful in exploring the effects of physical and thermal trauma on the rate of muscle useful in exploring the effects of physical and thermal trauma on the rate of muscle protein breakdown.

Aging↗
PubMed1983

Urinary 3-methylhistidine excretion in man: the role of protein-bound and soluble 3-methylhistidine.

The influence of dietary meat and meat stock intake on urinary excretion of 3-methylhistidine (3MH) was examined in human adults. In the absence of 3MH ingestion for 48 h, the study subjects adjusted to an intrinsic urinary 3MH: creatinine value. If the meat and meat stock-free diet was maintained on subsequent days, only minute diurnal variations occurred, and the values of random urine samples during the day were representative of the 24 h 3MH: creatinine value. The mean 3MH: creatinine value (SD) for a group of adults (n 7) was 0.105 +/- 0.023 (mumol of 3MH/mg creatinine), which is approximately 35% lower than the corresponding value in healthy growing infants (0.148 +/- 0.039) (Seashore et al. 1981). Ingestion of meat soup and meat causes different patterns of urinary excretion of 3MH which are consistent with the finding that meat extracts, such as soup and stock, contain considerable amounts of 3MH. The 3MH contents of beef, chicken and turkey were 3.8 +/- 0.15, 3.0 +/- 0.09 and 2.3 +/- 0.29 mumol/g dry wt meat respectively. All three meats contained a water-soluble 3MH-fraction (% total 3MH: beef 8, chicken 21, turkey 23). Amino acid analysis of the soluble fraction with or without hydrochloric acid hydrolysis demonstrated free 3MH in chicken and turkey (5.2 and 2.8% of the total respectively) but not in beef. Patients undergoing urinary 3MH measurements should maintain a diet that is free not only of solid meats, but also of meat stock. The ingestion of commercial food products (e.g. frozen or canned meals, sauces, pizza, etc.) may impair the validity of such measurements because of their meat-stock content. A dietary regimen is presented which is based on a shorter 12 h urine collection. The shorter collection time is satisfactory in the light of the steady rate of 3MH-excretion after 2 d of a diet free of meat and meat stock.

Adult↗
PubMed1978

Effect of dietary protein on urinary excretion of 3-methylhistidine in rat.

The excretion of the amino acid 3-methylhistidine in urine has been shown to be correlated with protein catabolism in skeletal muscle. In rats, 3-methylhistidine is partly acetylated (N-acetyl-3-methylhistidine) and it has been proposed that the relative amounts of 3-methylhistidine and N-acetyl-3-methylhistidine in urine is age dependent. In this experiment the effect of dietary protein quality on urine excretion of 3-methylhistidine and N-acetyl-3-methylhistidine was studied. Six groups of rats (mean weight 80 g) were fed diets containing 10% protein of different quality, the net protein utilization ranging from 76.7 for egg albumin to 28.9 for wheat gluten. The excretion of non-acetylated 3-methylhistidine was not dependent on the diet. There was, however, a good correlation between protein quality and total urine 3-methylhistidine (3-methylhistidine plus N-acetyl-3-methylhistidine), the higher the protein quality, the greater being the excretion of total 3-methylhistidine. The relative amounts of 3-methylhistidine and N-acetyl-3-methylhistidine correlated with the mean body weight, but not the age, of the animals. This study therefore demonstrates that a relationship exists between the nutritive quality of the dietary protein and the urinary excretion of 3-methylhistidine in rats.

Animals↗
PubMed2004

Contractile protein breakdown in human leg skeletal muscle as estimated by [2H3]-3-methylhistidine: a new method.

3-Methylhistidine urinary excretion and net balances across the leg or forearm have been used as markers of contractile protein breakdown in muscle tissue. Here we investigate whether infusion of labeled 3-methylhistidine and the measurement of the arteriovenous dilution of the tracer with unlabeled 3-methylhistidine will result in more consistent and precise measurements of 3-methylhistidine rates of appearance and consequently muscle contractile protein breakdown rates in comparison with conventional arteriovenous concentration difference measurements. Six healthy volunteers were studied in the postabsorptive state and received a primed continuous infusion of 3-[2H3-methyl]- methylhistidine and L-[ring-2H5]-phenylalanine for 4 hours. 2H3-3-methylhistidine reached an isotopic steady state after 210 minutes in all subjects. Arteriovenous differences of 3-methylhistidine, measured by high-performance liquid chromatography (HPLC), showed both uptake and release from skeletal muscle, which is theoretically not likely to occur. The enrichment of 2H3-3-methylhistidine was consistently lower in the femoral vein than in the artery, and therefore a constant net release of 3-methylhistidine from the leg was observed. The mean rates of appearance for 3-methylhistidine and phenylalanine were 0.44 +/- 0.30 nmol x min(-1) x 100 mL(-1) and 11.2 +/- 5.7 nmol x min(-1) x 100 mL(-1), respectively. In summary, arteriovenous difference measurement of 2H3-3-methylhistidine enrichment is more reliable than measurement of arteriovenous difference of unlabeled 3-methylhistidine. Consequently, measuring rates of appearance from leg muscle using labeled 3-methylhistidine resulted in more consistent and accurate values of contractile protein degradation rates in human skeletal muscle.

Adult↗