Intrasperm Ca2+ modulation and human ejaculated sperm viability: influence of miconazole, clotrimazole and loperamide.

Elevation of intrasperm Ca(2+) is reported to influence viability of ejaculated spermatozoa. Human spermatozoa possess inositol triphosphate (IP(3))-sensitive Ca(2+) stores, which can be targeted for increasing intrasperm Ca(2+) level. The influence of agents affecting Ca(2+) homeostasis has been investigated. Miconazole nitrate, clotrimazole and loperamide hydrochloride produced a dose- and time-dependent decrease in viability, each requiring respectively 0.5, 1.0 and 1.0 mM for producing death of all sperm cells immediately upon addition to ejaculated human semen samples. The reduction in sperm viability was accompanied by elevation of intrasperm Ca(2+) and was not affected by presence or absence of extracellular Ca(2+). Significantly (P<0.05) less time was required for producing complete loss of sperm viability and increasing intrasperm Ca(2+) when any of these drugs was added to sperm cells previously treated with selected agents affecting Ca(2+) homeostasis. This enhanced spermicidal activity of miconazole, clotrimazole and loperamide appeared to be due to further mobilization of Ca(2+) from partially depleted intrasperm Ca(2+) stores. Synergism of spermicidal activity and intrasperm Ca(2+) elevation by miconazole or clotrimazole was observed when Ca(2+) efflux from sperm cells was simultaneously inhibited by 2',4'-dichlorobenzamil hydrochloride, a Na(+)-Ca(2+) exchange inhibitor. The spermicidal activity of miconazole, clotrimazole or loperamide due to elevation of intrasperm Ca(2+) and its synergism, therefore, has great potential for exploitation of these drugs as contact spermicides.