Membrane potential hyperpolarization induces cytoplasmic alkalinization of mouse sperm

To gain fertilization ability sperm must undergo a series of physiological modification inthe female tract called capacitation, which leads to the acquisition of hyperactivatedmotility (HA) and the ability to undergo acrosome reaction (AR). Membrane potential(Em) hyperpolarization and alkalinization of the intracellular pH are necessary for HAand AR to take place. It has been reported either pharmacologically or genetically(potassium channel Slo3 knockout mice) that hyperpolarization is necessary andsufficient for sperm acrosomal responsiveness. In addition, intracellular alkalinizationallows the opening of CatSper channels which lead to an increase in intracellular calciumthat is fundamental for the HA of sperm. The aim of this work was to elucidate theinterplay between Em and pH in mouse sperm. We used BCECF-AM and DISC3(5), probesthat measures changes in cytoplasmic pH and Em, respectively. First, we studied thedependence of pH and Em, by co-incubating sperm with both probes followed by FlowCytometry analysis. We observed that all the cells were grouped into two populations:1) low pH and depolarized Em or 2) high pH and hyperpolarized Em. We also determinedthat sperm incubated under non-capacitating conditions with the addition of 1 μMvalinomycin displayed a robust increase in pH suggesting that changes in Em arenecessary for the rise in pH observed during capacitation. This increase was abrogatedin the presence of high K+ in the extracellular space. In addition, we studied the kineticsof this changes by assessing Em and pH at different time points of capacitation (0 to 60min). Our results showed that there is a rapid pH alkalinization during the first 15 min ofincubation in capacitating medium that is followed by a transient acidification at 30 min.Alkalinization is then restored at 45 min and remain unchanged. Thus, our resultssuggested that changes in the Em induces modifications in intracellular pH during mousesperm capacitation.Fil: Balestrini, Paula Ania. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Jabloñski, Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Gilio, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Luque, Guillermina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Krapf, Dari. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Mariano Gabriel Buffone. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaLXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica; LI Reunión Anual de la Asociación Argentina de Farmacología Experimental; XXI Reunión Anual de la Sociedad Argentina de Biología; XXXI Reunión Anual de la Sociedad Argentina de Protozoología; IX Reunión Anual de la Asociación Argentina de Nanomedicinas y VI Reunión Científica Regional de la Asociación Argentina de Ciencia y Tecnología de Animales de LaboratorioMar del PlataArgentinaSociedad Argentina de Investigación ClínicaSociedad Argentina de BiologíaSociedad Argentina de ProtozoologíaAsociación Argentina de Ciencia y Tecnología de Animales de LaboratorioAsociación Argentina de Nanomedicina