HUMAN SPERM MEMBRANE POTENTIAL AND ITS ROLE IN THEIR FERTILIZING CAPACITY

CARLOS CARIZZA; LIS PUGA MOLINA; DARIO KRAPF; CINTIA STIVAL; VALENTINA TORRES MONSERRAT; MARIANO G BUFFONE; CARLA RITAGLIATI; CAROLINA BARO GRAF

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Mammalian sperm cannot fertilize the egg without suffering certainphysiological changes triggered during its course through the female reproductivetract. These changes are known as capacitation and involve plasma membrane reorganization, extensivechanges in the state of protein phosphorylation and ion membrane-permeability. This ionpermeability changes impact on the plasma membrane potential (Em)of any animal cell, which is typically negatively charged inside. Emhyperpolarization associated to capacitation is well described for mouse sperm,and it is both necessary and sufficient for sperm to undergo the acrosomereaction. However, little is known about Em changes during human sperm capacitationand its relation to fertilizing capacity. To address this question we have setup a fluorimetric population assay for measuring human sperm membranepotential, by means of the cationic carbocyanine DiSC(3)5. Em was calculatedfor each sperm sample using the Nernst equation and considering anintracellular potassium concentration of 120 mM. Our results show a highdispersion of resting Em values of non-capacitated sperm. However, Em hyperpolarizationwas observed in most cases upon incubation of 3 to 5 hrs in capacitating media,regardless of the initial value. When analyzing sperm from patients attendingto reproductive clinics, a greater dispersion was observed, but Em hyperpolarizationwas hardly seen. In addition, Em values are compared to Computer Assisted SpermAnalysis data and to fertilization outcome, after assisted reproductivetechniques. These data have the potential value to add diagnostic tools to helppredict the success of different reproductive techniques.