title: Role of histidyl dipeptides in contractile function of fast and slow motor units in rat skeletal muscle.
abstract: The physiological role of the muscle histidyl dipeptides carnosine and anserine in contractile function of various types of muscle fibers in vivo is poorly understood. Ten adult male Wistar rats were randomly assigned to two groups: control and supplemented for 10 wk with beta-alanine, the precursor of carnosine (∼640 mg·kg body wt(-1)·day(-1)). Thereafter, contractile properties and fatigability of isolated fast fatigable (FF), fast resistant to fatigue (FR), and slow motor units (MUs) from the medial gastrocnemius were determined in deeply anaesthetized animals. The fatigue resistance was tested with a 40-Hz fatigue protocol followed by a second protocol at 40 Hz in fast and 20 Hz in slow units. In the supplemented rats, histidyl dipeptide concentrations significantly increased (P < 0.05) by 25% in the red portion of the gastrocnemius, and carnosine increased by 94% in the white portion. The twitch force of FF units and maximum tetanic force of FR units were significantly increased (P < 0.05), and the half-relaxation time was prolonged in slow units (P < 0.05). FF units showed less fatigue during the first 10 s, and FR units showed higher forces between 10 and 60 s during the 40-Hz fatigue test. In slow units, forces declined less during the first 60 s of the 20-Hz test. In conclusion, this in vivo experiment demonstrates that an elevation in muscle histidyl dipeptide content elicits beneficial changes in MU contractile characteristics and fatigue resistance. Carnosine and anserine seem to play an important yet divergent role in various MUs.
authors.affiliation: Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Physiology, Biochemistry and Hygiene, Poznan University of Physical Education, Poznań, Poland; kaczmarek@awf.poznan.pl.
authors.forename: Dominik
authors.initials: D
authors.lastname: Kaczmarek
authors.affiliation: Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland; Department of Motor Rehabilitation, Poznan University of Physical Education, Poznań, Poland; and.
authors.forename: Dawid
authors.initials: D
authors.lastname: Łochyński
authors.affiliation: Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
authors.forename: Inge
authors.initials: I
authors.lastname: Everaert
authors.affiliation: Department of Physiology, Biochemistry and Hygiene, Poznan University of Physical Education, Poznań, Poland;
authors.forename: Maciej
authors.initials: M
authors.lastname: Pawlak
authors.affiliation: Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Derave
authors.affiliation: Department of Neurobiology, Poznan University of Physical Education, Poznań, Poland;
authors.forename: Jan
authors.initials: J
authors.lastname: Celichowski
mesh_terms: D000818:Animals; D004151:Dipeptides / Q000378:metabolism*; D005221:Fatigue / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009046:Motor Neurons / Q000378:metabolism / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D015091:beta-Alanine / Q000378:metabolism
chemical_list: D004151:Dipeptides; D015091:beta-Alanine
keywords: beta-alanine; carnosine; fatigue; motor units; rat