MUSCLE ADENINE-NUCLEOTIDE DEGRADATION IN THE THOROUGHBRED HORSE AS A CONSEQUENCE OF RACING

1. Adenine nucleotide (AN) degradation as a result of racing was examined in thoroughbred horses. 2. Muscle ATP loss in some horses was as great as 50% and in all cases was matched by an equivalent increase in IMP. Mean post-exercise IMP contents varied little with race distance but individual values varied considerably within each race. 3. Results demonstrate that significant AN degradation occurs in muscle as a result of racing and further indicates that the onset of this process is associated with the fall in muscle pH to values probably less than 6.8.