title: Absolute quantification of carnosine in human calf muscle by proton magnetic resonance spectroscopy.
abstract: Carnosine has been shown to be present in the skeletal muscle and in the brain of a variety of animals and humans. Despite the various physiological functions assigned to this metabolite, its exact role remains unclear. It has been suggested that carnosine plays a role in buffering in the intracellular physiological pHi range in skeletal muscle as a result of accepting hydrogen ions released in the development of fatigue during intensive exercise. It is thus postulated that the concentration of carnosine is an indicator for the extent of the buffering capacity. However, the determination of the concentration of this metabolite has only been performed by means of muscle biopsy, which is an invasive procedure. In this paper, we utilized proton magnetic resonance spectroscopy (1H MRS) in order to perform absolute quantification of carnosine in vivo non-invasively. The method was verified by phantom experiments and in vivo measurements in the calf muscles of athletes and untrained volunteers. The measured mean concentrations in the soleus and the gastrocnemius muscles were found to be 2.81 +/- 0.57/4.8 +/- 1.59 mM (mean +/- SD) for athletes and 2.58 +/- 0.65/3.3 +/- 0.32 mM for untrained volunteers, respectively. These values are in agreement with previously reported biopsy-based results. Our results suggest that 1H MRS can provide an alternative method for non-invasively determining carnosine concentration in human calf muscle in vivo.
authors.affiliation: Department of Electronics and Information Systems, MEDISIP, Ghent University-IBBT-IBiTech, De Pintelaan 185 block B, B-9000 Ghent, Belgium. mahir.ozdemir@ugent.be <mahir.ozdemir@ugent.be>
authors.forename: Mahir S
authors.initials: MS
authors.lastname: Ozdemir
authors.forename: Harmen
authors.initials: H
authors.lastname: Reyngoudt
authors.forename: Yves
authors.initials: Y
authors.lastname: De Deene
authors.forename: Hakan S
authors.initials: HS
authors.lastname: Sazak
authors.forename: Els
authors.initials: E
authors.lastname: Fieremans
authors.forename: Steven
authors.initials: S
authors.lastname: Delputte
authors.forename: Yves
authors.initials: Y
authors.lastname: D'Asseler
authors.forename: Wim
authors.initials: W
authors.lastname: Derave
authors.forename: Ignace
authors.initials: I
authors.lastname: Lemahieu
authors.forename: Eric
authors.initials: E
authors.lastname: Achten
mesh_terms: D000465:Algorithms; D002336:Carnosine / Q000032:analysis*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D018482:Muscle, Skeletal / Q000378:metabolism*; D011522:Protons; D013848:Thigh; D014018:Tissue Distribution
chemical_list: D011522:Protons; D002336:Carnosine