Fig. 8.
Capacitation-associated hyperpolarization model. We propose that [Na+]i is decreased when sperm are incubated under conditions that support capacitation. This decrease is blocked by amiloride and stimulated by genistein, a CFTR activator, and also by cAMP agonists. Taking this information into consideration, our working hypothesis postulates that the increase in cAMP levels that accompany capacitation is responsible for CFTR activation with the consequent inhibition of ENaC and the hyperpolarization of the sperm Em. SACY, soluble adenylyl cyclase.