Influence of chlorpromazine on motility and calcium uptake of boar sperm.

In the motility of sperm, which resembles the automaticity of smooth muscle in some features, calcium plays an important role. Chlorpromazine (CPZ), an inhibitor of calmodulin (CaM), decreases contractile responses of smooth muscle to agonists, alters microsomal calcium movements and inhibits human sperm motility. The involvement of CaM in the contraction of smooth muscle and in sperm motility and its presence in sperm cells have also been established. Therefore, the effects of CPZ on boar sperm motility and microsomal calcium uptake were studied. CPZ (0.05-0.5 mM) was found to depress the motility index of boar sperm. At 60 min time point, an inhibition of the motility index ranging from 28 to 85% was observed (p less than 0.05). The spermatozoa microsomal calcium uptake (5.2 nmol/mg protein/hr) was Mg++- and ATP-dependent and azide insensitive. Ionophore A23187 (1 microM) and EDTA (10 mM) inhibited the uptake (67-94%). The calcium uptake was inhibited (40-60%) by CPZ (0.25 and 0.5 mM). The CPZ-induced inhibition of the motility index or calcium uptake was overcome by additional CaCl2. The observations suggested that the CPZ-caused changes were calcium-mediated and possibly involved CaM.