Oviductal high concentration of K+ suppresses hyperpolarization but does not prevent hyperactivation, acrosome reaction and in vitro fertilization in hamsters.

Oviductal high concentration of K+ suppresses hyperpolarization but does not prevent hyperactivation, acrosome reaction and in vitro fertilization in hamsters. Zygote. 2020 Oct 05;:1-9 Authors: Takei GL, Kon H Abstract Mammalian sperm have to undergo capacitation to be fertilization competent. Capacitated sperm in vitro show hyperpolarization of the membrane potential. It has been reported that in mouse membrane hyperpolarization is necessary for the acrosome reaction. We recently found that the fluid of the hamster oviduct, where fertilization occurs, contained a high potassium (K+) concentration (~20 mEq/l). This high K+ concentration could depolarize the membrane potential and prevent the acrosome reaction/fertilization. Conversely, some beneficial effects on capacitation of high K+ concentration or a high K/Na ratio were also reported. In the present study, we investigated the effects of oviduct high K+ concentration on hamster sperm capacitation-associated events and fertilization. The present study confirmed that, in hamster sperm, membrane potential was hyperpolarized upon in vitro capacitation, indicating that capacitation-associated hyperpolarization is a universal phenomenon among mammalian species. An increase in KCl concentration in the medium to 20 mM significantly depolarized the membrane potential and suppressed hyperpolarization when in the presence of >101 mM NaCl. However, an increase in the KCl concentration to ...
Source: Zygote - Category: Reproduction Medicine Authors: Tags: Zygote Source Type: research