Intracellular changes in Ca2Â +, K+ and pH after sperm motility activation in the European eel (Anguilla anguilla): Preliminary results

It was observed that levels of intracellular Ca2 + and K+ sperm ions increased significantly 30 s after the hyperosmotic shock compared to baseline levels, and remained at this level until 120 s post-activation. In contrast, the intracellular pH remained constant during the first 30 s, and decreased gradually at 60 and 120 s post-activation. Our data agree with the current main theory for explaining motility activation in marine fish, in which internal fluctuations of Ca2 + and K+ seem to participate in sperm activation. In addition, fluorescent images showed that both Ca2 + and K+ were concentrated in the apical area of the sperm head, which corresponds to the location of the eel sperm mitochondria, suggesting this organelle plays an important role in sperm motility activation.