[H-3] HEPARIN-BINDING IN BOAR SPERMATOZOA - CHARACTERIZATION AND CORRELATION WITH ROUTINE SEMEN QUALITY PARAMETERS

A simple technique has been established for the purpose of characteriz ing heparin binding to boar sperm. Binding experiments were performed using [H-3]heparin and extended boar semen. [H-3]Heparin binding to bo ar sperm was effectively displaced by increasing concentrations of hep arin. [H-3]Heparin binding was linear at least between 50 000 and 10(6 ) spermatozoa and was stable for at least 120 min. Binding was sensiti ve to fucoidan, chondroitin sulfate B, chondroitin sulfate C, and chon droitin sulfate A, while keratan sulfate had only a marginal effect on binding. The [(3)Hheparin binding was saturable. Assuming a 13 000 M( r) for the [H-3]heparin used, binding to boar spermatozoa showed an ap parent equilibrium dissociation constant (K-d) of 23.6 +/- 2.5 nM and a maximum binding capacity (B-max) of 6.0 +/- 1.1 pmol/10(6) spermatoz oa (average values from 6 boars, means +/- SEM). Interejaculate variat ions in binding parameters were dependent on the male. Thus, with resp ect to B-max variation, 4 of 6 boars studied exhibited an interejacula te coefficient of variation of less than 0.33 (0.09, 0.11, 0.11, and 0 .29, respectively, for 3 consecutive ejaculates), while in the case of K-d interejaculate variation, only 2 of the 6 boars studied showed ac ceptable variation coefficients (0.16 and 0.28). No seasonal effect wa s observed in either of the binding parameters, with the variations fo llowing boar-specific patterns. K-d and B-max intermean differences fo r different boars during the course of the study period (April-lune) w ere not significant (p > 0.05). Correlations of mean boar binding para meters (K-d, and B-max) with conventional semen quality parameters sho wed a correlation between B-max values and those of the osmotic resist ance test (r = 0.8990, p < 0.01), normal acrosomes (r = 0.7946, p < 0. 05), and bended tails (r = -0.8632, p < 0.02). K-d values were correla ted with cytoplasmic distal droplet (r = -0.7992, p < 0.05). The glyco saminoglycans and polysulfated boar sperm binding sites reported in th e present work should be regarded as binding sites until further studi es elucidate their physiological role. The results obtained suggest th at this technique be given a role as a research tool.