TABLE 1

Potencies of mibefradil and ML218 to inhibit calcium influx produced by PROG, PGE1, l-sirenin, and high K+/high pH in human sperm

OpenerBlockerpIC50n
PROGmibefradil5.17 ± 0.247
ML2185.02 ± 0.084
PGE1mibefradil5.08 ± 0.318
ML2184.87 ± 0.153
l-sireninmibefradil5.09 ± 0.345
ML2184.85 ± 0.173
high K+/high pHmibefradil4.76 ± 0.098
ML2184.99 ± 0.167
  • Inhibitors were evaluated in the presence of an EC80 concentration of each activator (30 nM PROG, 10 nM PGE1, 3 µM l-sirenin). Buffer containing 140 mM K+, pH 8.2 was added to elicit alkalinization/depolarization calcium influx. pIC50 values are expressed as the mean ±SD with the number of independent experiments indicated by n.