Receive exclusive offers and updates from Oxford Academic. This might also explain why only 10 nM cAMP is sufficient to trigger capacitation, and why micromolar concentrations of adenosine are necessary Old in sperm trigger stimulatory responses Shen et al. An aliquot was air dried onto slides and permeabilized in methanol for 10 min at 4°C. Related articles in Web of Science Google Scholar. Compartmentalization of distinct cAMP signaling pathways in mammalian sperm.