Effects of factors released from eggs and other agents on cyclic nucleotide concentrations of sea urchin spermatozoa

Factors released from eggs (FRE) of the sea urchin, Strongylocentrotus purpuratus, caused up to 20-fold increases in sperm cyclic AMP levels after a 1-min incubation. Putative cyclic nucleotide phosphodiesterase inhibitors such as theophylline acted in a synergistic manner with FRE to cause even greater increases in sperm cyclic AMP levels. This effect appeared to be specific for egg factors since various hormones (triiodothyronine, norepinephrine, histamine), nucleosides (adenosine, guanosine), nucleophiles (axide), anaesthetics (procaine), ionophores (X537A, A23187), metals (Mn2+) and neurotransmitters (acetylcholine) did not increase sperm cyclic AMP levels. Various mammalian tissue extracts (serum, uterus, adrenal, ovary, lung) also had no effect. We suggest that the activity which elevates the cyclic AMP of sea urchin spermatozoa is specifically associated with sea urchin eggs.