Flagellar ion channels of sperm: similarities and differences between species

• Sperm intracellular pH, membrane voltage (Vm) and [Ca2+]i re all important for sperm activity.
• Ion homeostasis and Vm are under control of sperm ion channels and transporters. They regulate sperm motility and ability to fertilize an egg.
• Sperm ion channels are diverse and could differ between species in respect to their regulation.
• Here we summarize the current knowledge about flagellar ion channels of mammalian sperm.

Motility and fertilization potential of mammalian sperm are regulated by ion homeostasis which in turn is under tight control of ion channels and transporters. Sperm intracellular pH, membrane voltage and calcium concentration ([Ca2+]i) are all important for sperm activity within the female reproductive tract. While all mammalian sperm are united in their goal to find and fertilize an egg, the molecular mechanisms they utilize for this purpose are diverse and differ between species especially on the level of ion channels. Recent direct recording from sperm cells of different species indicate the differences between rodent, non-human primate, ruminant, and human sperm on the basic levels of their ion channel regulation. In this review we summarize the current knowledge about ion channel diversity of the animal kingdom and concentrate our attention on flagellar ion channels of mammalian sperm.

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