Induction of Motility in Immature Bovine Spermatozoa by Cyclic AMP Phosphodiesterase Inhibitors and Seminal Plasma

Abstract

Motility can be induced in immature spermatozoa from the bovine caput epididymidis by cyclic 3′,5′-adenosine monophosphate (cAMP) phosphodiesterase inhibitors (PDIs) and bovine seminal plasma. PDIs alone indicate flagellar activity without forward progression. Initiation of maximal movement without forward progression requires the presence of high levels of PDIs and is characterized by a distinct lag phase, the duration of which depends on the nature and concentration of the inhibitor. With theophylline (10 mM), for example, the cells reach maximal activity after 12–13 min. That theophylline owes its efficacy to an inhibition of phosphodiesterase is indicated by the fact that cyclic AMP levels increase 3- to 4-fold after the addition of theophylline and reach a maximal level (700 pmoles/109 sperm) several minutes before peak flagellar activity.