title: Whole body creatine and protein kinetics in healthy men and women: effects of creatine and amino acid supplementation.
abstract: Creatine kinetics were measured in young healthy subjects, eight males and seven females, age 20-30 years, after an overnight fast on creatine-free diet. Whole body turnover of glycine and its appearance in creatine was quantified using [1-(13)C] glycine and the rate of protein turnover was quantified using L-ring [(2)H5] phenylalanine. The creatine pool size was estimated by the dilution of a bolus [C(2)H3] creatine. Studies were repeated following a five days supplement creatine 21 g.day(-1) and following supplement amino acids 14.3 g day(-1). Creatine caused a ten-fold increase in the plasma concentration of creatine and a 50 % decrease in the concentration of guanidinoacetic acid. Plasma amino acids profile showed a significant decrease in glycine, glutamine, and taurine and a significant increase in citrulline, valine, lysine, and cysteine. There was a significant decrease in the rate of appearance of glycine, suggesting a decrease in de-novo synthesis (p = 0.006). The fractional and absolute rate of synthesis of creatine was significantly decreased by supplemental creatine. Amino acid supplement had no impact on any of the parameters. This is the first detailed analysis of creatine kinetics and the effects of creatine supplement in healthy young men and women. These methods can be applied for the analysis of creatine kinetics in different physiological states.
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, NE-40, 9500 Euclid Av, Cleveland, OH, 44195, USA. sck@case.edu.|Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, USA. sck@case.edu.
authors.forename: Satish C
authors.initials: SC
authors.lastname: Kalhan
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, NE-40, 9500 Euclid Av, Cleveland, OH, 44195, USA.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Gruca
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, NE-40, 9500 Euclid Av, Cleveland, OH, 44195, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Marczewski
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, NE-40, 9500 Euclid Av, Cleveland, OH, 44195, USA.
authors.forename: Carole
authors.initials: C
authors.lastname: Bennett
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: China
authors.initials: C
authors.lastname: Kummitha
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood; D003401:Creatine / Q000097:blood* / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007700:Kinetics; D008297:Male; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D055815:Young Adult
chemical_list: D000596:Amino Acids; D011506:Proteins; D003401:Creatine
keywords: Creatine; Glycine; Guanidinoacetic acid; Kinetics; Phenylalanine; Stable isotopes