Bioenergetics of fish spermatozoa during semen storage.

This mini-review focuses on changes in ATP and creatine phosphate concentrations in fish sperm under storage conditions. The storage of catfish sperm at 4 degrees C leads to ATP depletion and decreased sperm motility. The rate of intracellular ATP depletion can be diminished through the addition of energetic substrates to the sperm storage medium, with lactate + pyruvate being the most efficient substrates for maintaining ATP concentrations in catfish sperm. The decrease in ATP concentration is closely associated with increases in AMP and hypoxanthine content. In contrast to catfish sperm, carp sperm is able to maintain intracellular ATP concentration close to the physiological level during storage. Collectively, these results suggest that fish species differ in terms of the energy metabolism of their spermatozoa and that the semen storage medium must be carefully selected for a particular fish species so as to maintain the ATP concentration and adenylate energy charge close to physiological values as long as possible.