Creatine kinase-dependent energy transport in sea urchin spermatozoa. Flagellar wave attenuation and theoretical analysis of high energy phosphate diffusion

The significance of a phosphocreatine (PCr) shuttle in the energy transport of motile spermatozoa (Tombes, R. M., and B. M. Shapiro, 1985, Cell, 41:325–334) has been tested by a quantitative analysis of motility. Computer-assisted analysis of stroboscopic photomicrographs of live sea urchin spermatozoa whose creatine kinase has been specifically inhibited by fluorodinitrobenzene reveals that motility is impaired due to a progressive damping of bending waves as they propagate along the flagellum. This lesion, which has been defined as attenuation and can be quantified, is repaired when these spermatozoa are demembranated and reactivated to swim with ATP. The implication that attenuation is due to the inhibition of energy transport via a PCr shuttle resulting in the decrease of ATP and accumulation of inhibitory levels of ADP distally has been supported by calculating sperm PCr and ATP levels resulting from diffusion along the flagellum. The specific alterations of motility seen with creatine kinase inhibition and their reversal with ATP are as expected from the model and provide strong support for the PCr shuttle in high energy phosphate transport.