Cell calcium of ejaculated rabbit spermatozoa before and following in vitro capacitation

Ejaculated rabbit spermatozoa were loaded with the calcium-selective fluorescent indicator quin-2. Measurements of trypan blue exclusion indicated that cell viability was not affected by quin-2 loading. The concentration of intracellular free calcium of quin-2 loaded sperm was calculated to be 144 +/- 14 nM. Spermatozoa capacitated in vitro either before or following quin-2 loading had intracellular free calcium levels similar to that of non-capacitated sperm. These studies indicate that the concentration of intracellular free calcium of ejaculated rabbit spermatozoa does not change as a result of in vitro capacitation.