Effects of manganese and other divalent cations on progressive motility of human sperm

Manganese (Mn2+) stimulated the progressive motility of human washed sperm in a time- and dose-dependent manner. This confirmed previous data indicating a capacity for activating the adenylyl cyclase of sperm homogenates in vitro. A maintained response was best seen with doses 0.2-1.0 mM. After an initial stimulation, higher concentrations of up to 20 mM were associated with a decline in the response to control levels. Magnesium ions (Mg2+) stimulated motility in the same dose range but to less than 50% of the Mn2+ response. Other divalent cations such as zinc (Zn2+), strontium (Sr2+), and Calcium (Ca2+) also exerted stimulatory effects to varying degrees in descending order. Metal ion effects on sperm motility may be mediated through a common cation-binding site on the adenylyl cyclase.