Interesting stuff I found on carnosine:
Laboratory of Marine Biochemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
[email protected].
The intracellular non-bicarbonate buffering capacity of vertebrate muscle is mainly supported by the imidazole groups of histidine residues in proteins, free L-histidine in some fish species, and histidine-containing dipeptides such as carnosine, anserine, and balenine (ophidine). The proton buffering capacity markedly differs between muscle types and animal species depending on the ability for anaerobic exercise. The capacity is typically high in fast-twitch glycolytic muscles of vertebrates adapted for anaerobic performance such as burst swimming in fishes, prolonged anoxic diving in marine mammals, flight in birds, sprint running in mammalian sprinters, and hopping locomotion in some terrestrial mammals.
A high correlation between buffering capacity, concentration of histidine-related compounds in muscle, and percentage of fast-twitch fibers in all vertebrates adapted for intense anaerobic performance clearly supports the idea that proton buffering is the main physiological function of histidine-related compounds.
High level of skeletal muscle carnosine contributes to the latter half of exercise performance during 30-s maximal cycle ergometer sprinting.
Suzuki Y, Ito O, Mukai N, Takahashi H, Takamatsu K.
Doctoral Program in Health and Sport Sciences, University of Tsukuba, Japan.
The histidine-containing dipeptide carnosine (beta-alanyl-L-histidine) has been shown to significantly contribute to the physicochemical buffering in skeletal muscles, which maintains acid-base balance when a large quantity of H(+) is produced in association with lactic acid accumulation during high-intensity exercise. The purpose of the present study was to examine the relations among the skeletal muscle carnosine concentration, fiber-type distribution, and high-intensity exercise performance. The subjects were 11 healthy men. Muscle biopsy samples were taken from the vastus lateralis at rest. The carnosine concentration was determined by the use of an amino acid autoanalyzer. The fiber-type distribution was determined by the staining intensity of myosin adenosinetriphosphatase. The high-intensity exercise performance was assessed by the use of 30-s maximal cycle ergometer sprinting. A significant correlation was demonstrated between the carnosine concentration and the type IIX fiber composition (r=0.646, p<0.05).
The carnosine concentration was significantly correlated with the mean power per body mass (r=0.785, p<0.01) during the 30-s sprinting. When dividing the sprinting into 6 phases (0-5, 6-10, 11-15, 16-20, 21-25, 26-30 s), significant correlations were observed between the carnosine concentration and the mean power per body mass of the final 2 phases (21-25 s: r=0.694, p<0.05; 26-30 s: r=0.660, p<0.05). These results indicated that the carnosine concentration could be an important factor in determining the high-intensity exercise performance.
Dupin AM, Stvolinskii SL.
Carnosine content in muscles functioning under single or tetanic (both direct and indirect) contractions, in the period of active contractility (within the first 10 min of experiment) and in fatigued muscles was determined. In exercising muscle, carnosine content was shown to decrease. The loss of the dipeptide during active contractions was, on the average, 10.5%; that at fatigue--13.8%. At exercise (single contractions), the decrease of carnosine was higher than in the muscles functioning in a short tetanus regime.
It was shown that the previously described phenomenon of fatigue elimination by carnosine addition to the Ringer solution washing the muscle is concomitant with the elevation (by 12%) of the intramuscular concentration of exogenous carnosine.
Parkhouse WS, McKenzie DC.
Sprint-trained athletes demonstrate a remarkable ability to perform exercise which results in fatigue quickly. However, the mechanisms for these enhanced performance capabilities have not been fully elucidated. Elevation in glycolytic enzymes and increased fast-twitch fiber compositions which would result in an enhanced ability to produce ATP do not appear to be capable of accounting for the greatly enhanced performances. Associated with these performances are large accumulations of anaerobic end products which produce decrements in intracellular pH. Because intracellular pH decrements of sufficient magnitude have been shown to inhibit athletic performances, it has been postulated that sprint-trained athletes have an enhanced proton-sequestering capability which would ultimately alter the rate of pH decrement. This would delay the inhibition of the enzymatic and contractile machinery resulting in enhanced performances.
The intracellular buffers that are capable of contributing to this enhanced buffering capacity were identified as inorganic phosphate, protein-bound histidine residues, the dipeptide carnosine, bicarbonate, and creatine phosphate. Thus, it has been suggested that increased buffer capacities within sprint-trained athletes may be a contributing factor to his/her enhanced anaerobic performance capacities.
I found this last statement of particular interest, because it suggests that increased carnosine levels might increase buffering capacities just like creatine does (although through a different pathway). Perhaps this would mean it has muscle building capabilities as creatine has.
