ACUTE EFFECT OF EXERCISES UPON THE CONCENTRATIONS OF
HYALURONIC ACID AND CHONDROITIN SULFATE IN SYNOVIAL FLUID
OF ATHLETIC HORSES
Luciane Rasera1, Raquel Y. A. Baccarin1, Roberto P. P. Foz Filho, Aline Mendes2, Yara
M. Michelacci2, João Roberto M. Martins2.
Introduction: It is well known that hyaluronic acid (HA) is very important for the
viscosity of the synovial fluid. In fact, decreases in either HA concentration or molecular
size lead to proportional decreases in synovial fluid viscosity. Chondroitin sulfate (CS) is
also present in the synovial fluid, and it is believed that it comes, at least in part, from the
cartilage matrix, where it corresponds to more than 10% of the tissue dry weight.
Objective. The objective of the present study was to investigate the acute effect of
physical exercises upon the concentrations of AH and CS in synovial fluid of athletic
horses. Material and Methods: Synovial fluid samples (0.5 ml) were collected from ten
metacarpophalangeal joints of adult polo ponies, high handicap, submitted to the same
training program, immediately before the polo game, and 3 h, 6 h, and 24 h after the end
of the game. Synovial fluid samples were also collected from six metacarpophalangeal
joints of sedentary horses that did not present any signs of joint diseases, as controls. AH
and CS were identified by agarose gel electrophoresis after proteolysis, and quantified by
densitometry. Results: The concentrations of HA (344 µg/mL) and CS (22 µg/mL) in
synovial fluid of athletes were significantly lower (P<0.05) than in sedentary controls
(HA, 601 µg/mL, and CS, 43 µg/mL). The concentration of AH tends to increase 3 h
(410 µg/mL), 6 h (379 µg/mL), and 24 h (427 µg/mL) after the game, but the differences
were not statistically significant. In contrast, statistically significant increases in the
concentration of CS occurred 3 h (396 µg/mL, P<0.10) and 6 h after the game (572
µg/mL, P<0.05). Although the concentrations were also increased 24 h after the game
(174 µg/mL), this difference was not statistically significant. Discussion and
Conclusion: The lower synovial fluid concentrations of HA and CS in athletes, when
compared to sedentary normal horses, could be due to the higher volumes of synovial
fluid in athletic animals. In contrast, the increase in CS concentration a few hours after
intense physical exercises seems to indicate an increased catabolic breakdown of
cartilage proteoglycans, possibly in consequence of the mechanical stress.
Acknowledgements – Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP).
Ethical committee- FMVZ – USP (protocol n° 527/2004)
1
Faculdade de Medicina Veterinária e Zootecnia – USP- São Paulo – Brasil. [email protected]
2
Departamento de Bioquímica – UNIFESP- São Paulo – Brasil