Study the role of KSper current for controlling the Ca2+ influx and intracellular pHi in mouse spermatozoa by dominating membrane potentials

Abstract

This work was aimed to explore the details of the ion channels gating and there physiological role in sperm in the future.Mouse spermatozoa express a pH-dependent K+ current (KSper) thought to induce hyperpolarization to enhance Ca2+ influx via alkaline-activated calcium channel (Catsper) to initial a so-called sperm capacitation by NH4Cl during travelling in female genital tract for fertilization. However, the regulating mechanism of the Ksper and Catsper channels by membrane potential and pHi remains uncertain, because the complexities of two channel kinetics in sperms is hardly to be overcame at this stage. Here we show that difference of the intracellular [Ca2+]i between the wild type (Wt) and knockout (KO) Ksper (or Slo3/) mice in the application of the Slo3 blockers, Guinidine (QD) and Clofilium, and NH4Cl, indicating that Ksper channels, encoding Slo3 gene, dominates the membrane potential of mouse sperms to increase the intracellular [Ca2+]i and [pH]i during the capacitation process to play a vital role in fertility. Furthermore, a HH model sperm built directly with the native Ksper and Catsper currents in sperms reveals two functions of membrane potential and intracellular pHi, allowing us to calculate the intracellular pHi by NH4Cl, based on membrane potentials recording from current-clamp experiments. During modeling, we found a caton channel with Vrev= +20 mV in mouse sperm from the double-KO (i.e. Catsper-/- and Ksper-/-) mice, which is definitely necessary for a model able to match the data.

Keywords

• fertilty,,
• ,،,؛ca2+ channel,,
• ,،,؛ko mice,,
• ,،,؛cation channel