a1 Department of Animal Sciences, Rutgers, The State University of New Jersey, 84 Lipman Drive, Bartlett Hall, New Brunswick, NJ, USA
The objective of this study was to compare exercise-induced inflammatory responses in horses undergoing three different treadmill exercise tests. Mares completed a graded exercise test (GXT), an interval exercise test (IET) and a repeated sprint exercise test (RSET). Blood and synovial fluid samples were taken 24 h before (PRE) exercise, 20–30 min, 2 and 24 h following exercise (REC). Blood was analysed for total protein, haematocrit and total nitrite concentration. Pro-inflammatory and anti-inflammatory cytokine transcripts were measured in whole blood using quantitative real-time polymerase chain reaction. Synovial fluid was analysed for total nitrite. Mares spent more time at greater than 90% of their maximum heart rate during the RSET than they did for either the GXT or IET. There was an effect of exercise test (P < 0.0001) and exercise test by sample interaction (P = 0.010) for plasma total nitrite. Pro-inflammatory cytokine transcripts and plasma total protein were elevated (P < 0.05) after exercise and there was a higher (P < 0.0001) nitrite concentration in tibiotarsal joints compared with radiocarpal joints. As hypothesised, the higher-intensity exercise test (RSET) resulted in greater nitric oxide responses as well as markers of exercise intensity compared with less intense exercise tests (IET, GXT).
(Received October 27 2008)
(Accepted January 22 2009)