| Abstract: | Adenylate cyclase activities were studied in porcine sperm in the presence and absence of Mn++ before and after incubation in vivo and in vitro. Incubation of sperm in vivo for 30 min increased the Mg++-stimulated adenylate cyclase activity from 35.1 pmoles cyclic AMP formed per mg protein per 10 min to 50.4 pmoles. The activity stimulated by Mg++ and Mn++ increased from 392 to 729 pmoles after 30 min of in vivo incubation. Activity after incubation in vivo for 120 min was not different from activity after 30 min. In vitro incubation of porcine sperm in Ca++-free Ringer-fructose resulted in no change, but incubation in oviductal and uterine flushings obtained from gilts soon after ovulation increased Mg++-stimulated activity by 24% and Mg++?+ Mn++-stimulated activity by 49%. In vitro incubations in preovulatory flushings plus follicular fluid or in bovine serum albumin also increased adenylate cyclase activity. |
