Na + /H + Exchangers Involve in Regulating the pH-Sensitive Ion Channels in Mouse Sperm

• Published in: International journal of molecular sciences Vol. 22; no. 4; p. 1612
• Main Authors: Kang, Hang, Liu, Min, Zhang, Wei, Huang, Rong-Zu, Zhao, Na, Chen, Chen, Zeng, Xu-Hui
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 05.02.2021; MDPI
• Subjects: Acidification; Amiloride; Calcium (intracellular); Calcium influx; Calcium ions; CatSper; cytosolic alkalization; Depolarization; Infertility; Intracellular; Ion channels; Ion exchangers; KSper; Membrane potential; Membranes; Motility; Na+/H+ exchangers; Na+/H+-exchanging ATPase; Physiology; Reproductive system; Sperm; sperm motility; CatSper; sperm motility; cytosolic alkalization; Na+/H+ exchangers; KSper; membrane potential
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms22041612

Sperm-specific K ion channel (KSper) and Ca ion channel (CatSper), whose elimination causes male infertility in mice, determine the membrane potential and Ca influx, respectively. KSper and CatSper can be activated by cytosolic alkalization, which occurs during sperm going through the alkaline environment of the female reproductive tract. However, which intracellular pH (pH ) regulator functionally couples to the activation of KSper/CatSper remains obscure. Although Na /H exchangers (NHEs) have been implicated to mediate pH in sperm, there is a lack of direct evidence confirming the functional coupling between NHEs and KSper/CatSper. Here, 5-(N, N-dimethyl)-amiloride (DMA), an NHEs inhibitor that firstly proved not to affect KSper/CatSper directly, was chosen to examine NHEs function on KSper/CatSper in mouse sperm. The results of patch clamping recordings showed that, when extracellular pH was at the physiological level of 7.4, DMA application caused KSper inhibition and the depolarization of membrane potential when pipette solutions were not pH-buffered. In contrast, these effects were minimized when pipette solutions were pH-buffered, indicating that they solely resulted from pH acidification caused by NHEs inhibition. Similarly, DMA treatment reduced CatSper current and intracellular Ca , effects also dependent on the buffer capacity of pH in pipette solutions. The impairment of sperm motility was also observed after DMA incubation. These results manifested that NHEs activity is coupled to the activation of KSper/CatSper under physiological conditions.