Atrial natriuretic peptide modulators: Dissociation of receptor binding and particulate guanylate cyclase activity

Atrial natriuretic peptide: a chemoattractant of human spermatozoa by a guanylate cyclase-dependent pathway

Atrial natriuretic peptide (ANP), found in mammalian ovarian granulosa cells and oocytes (Kim et al., 1992, 1993), induces the human acrosome reaction (Anderson et al., 1994). The purpose of the present study was to determine whether ANP, as egg-derived peptides from sea urchins, can act as a chemoattractant to human spermatozoa. Small lengths of capillary tubing that contained different concentrations of ANP were suspended over a suspension of washed spermatozoa. The number of spermatozoa that entered the tubing was determined. More than twice the number of spermatozoa moved into the tubing that contained a maximally effective concentration of ANP, as compared with tubing that contained only medium. The concentration of ANP that produced a half-maximal effect was 0.7 nM. The effect was blocked by LY83583, an inhibitor of guanylate cyclase. ANP produced more than a twofold increase in the rate of cGMP formation, an effect that was blocked by LY83583. Human ANP (5-27), a fragment of the intact peptide, had no chemoattractant activity. These findings suggest that a specific sperm receptor exists for the chemoattractant activity of ANP that is associated with guanylate cyclase. The chemoattractant activity of ANP is independent of the presence of extracellular calcium ions and is independent of the action of ANP as a stimulus of the acrosome reaction. There is no association between the chemoattractant activity of follicular fluid and the follicular fluid concentration of ANP. These data suggest that factors besides ANP are responsible for the chemoattractant activity of follicular fluid.(ABSTRACT TRUNCATED AT 250 WORDS)