Reactive oxygen-induced reactive oxygen formation during human sperm capacitation (original) (raw)

Physiological processes are often activated by reactive oxygen species (ROS), such as the superoxide anion (O 2 U -) and nitric oxide (NO U ) produced by cells. We studied the interactions between NO U and O 2 U -, and their generators (NO U synthase, NOS, and a still elusive oxidase), in human spermatozoa during capacitation (transformations needed for acquisition of fertility). Albumin, fetal cord serum ultrafiltrate, and L-arginine triggered capacitation and ROS generation (NO U and O 2 U -) and superoxide dismutase (SOD) and NOS inhibitors prevented all these effects. Surprisingly, capacitation due to exogenous NO U (or O 2 U -) was also blocked by SOD (or NOS inhibitors). Probes used were proven specific and innocuous on spermatozoa. Whereas O 2 Uwas needed only for 30 min, the continuous NO U generation was essential for hours.