Comparison between Inhibition of CatSper and KSper Channels with NNC 55-0396 and Quinidine on Human Sperm Function.

BACKGROUND: Calcium enters human sperm through the "Cation Channel of Sperm" (CatSper), while potassium ions exit via the sperm potassium channel (KSper). These two channels regulate intracellular calcium concentration ([Ca(2+)](i)) and membrane potential. Our study aims to investigate and compare the contributions of these channels in capacitated sperm function. RESULTS: NNC and quinidine significantly decreased progressive sperm motility (P=0.001) and reduced sperm kinematics (P=0.001). NNC but not quinidine significantly decreased sperm survival (P=0.001), reduced [Ca(2+)](i) in live spermatozoa (P=0.05), and induced the acrosomal reaction (P=0.012). CONCLUSION: Inhibition of KSper without effect on [Ca(2+)](i) can inhibit sperm motility and increase mortality rate. It seems that the function of KSper is as vital as CatSper in human sperm physiology.