ATP levels of chinook salmon (Oncorhynchus tshawytscha) sperm following in vitro exposure to various oxygen tensions

Adenosine triphosphate (ATP) levels in sperm from chinook salmon (Oncorhynchus tshawytscha) were found to be 12.1+/-1.9 pmol ATP per 10(6) sperm cells (mean+/-SEM, n=18). Sperm were stored at 0-2 degrees C for up to 72 h under 100, 21, and 0% O-2. Changes in sperm ATP content of samples maintained under 100 and 21% O-2 were indistinguishable, decreasing to 50% of initial values after 72 h. ATP levels of sperm stored under 0% O-2 decreased to 10% of initial values within 8 h and remained unchanged throughout the following 64 h. The initial percent of living sperm (sperm viability) was 94.7+/-1.7% (mean+/-SEM, n=12) and was unaltered at 24 h under all O-2 tensions. At 72 h, sperm viability remained unchanged under 21% O-2 and had decreased by 20% under 100% O-2 and by 30% under 0% O-2. Therefore, reductions in sperm ATP levels could not be attributed to cell lysis, as viability decreased only modestly over these durations. Fertilizing ability correlated positively with sperm ATP levels. Spermatocrit values increased by 20% for the samples maintained under 100 and 21% O-2 after 72 h. However, a 20% increase in spermatocrit occurred within 24 h in samples maintained under 0% O-2, rising 70% after 72 h under 0% O-2. These data indicate that chinook sperm ATP (1) can be altered and manipulated without significant loss of viability, (2) is positively associated with fertilization, and (3) probably plays a role in sperm packing and cell flexibility.