HUMAN SPERM MEMBRANE POTENTIAL AND ITS ROLE IN THEIR FERTILIZING CAPACITY

BUFFONE, MARIANO G.; RITAGLIATI, CARLA; BARÓ GRAF, CAROLINA; KRAPF, DARIO; STIVAL, CINTIA; TORRES MONSERRAT, VALENTINA; CARIZZA, CARLOS; PUGA MOLINA, LIS DEL C.

Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

Mammalian sperm cannot fertilize the egg without suffering certainphysiological changes triggered during its course through thefemale reproductive tract. These changes are known as capacitationand involve plasma membrane reorganization, extensive changes inthe state of protein phosphorylation and ion membrane-permeability.This ion permeability changes impact on the plasma membrane potential(Em) of any animal cell, which is typically negatively chargedinside. Em hyperpolarization associated to capacitation is well describedfor mouse sperm, and it is both necessary and sufficient forsperm to undergo the acrosome reaction. However, little is knownabout Em changes during human sperm capacitation and its relationto fertilizing capacity. To address this question we have set up a fluorimetricpopulation assay for measuring human sperm membranepotential, by means of the cationic carbocyanine DiSC(3)5. Em wascalculated for each sperm sample using the Nernst equation andconsidering an intracellular potassium concentration of 120 mM. Ourresults show a high dispersion of resting Em values of non-capacitatedsperm. However, Em hyperpolarization was observed in mostcases upon incubation of 3 to 5 hrs in capacitating media, regardlessof the initial value. When analyzing sperm from patients attendingto reproductive clinics, a greater dispersion was observed, but Emhyperpolarization was hardly seen. In addition, Em values are comparedto Computer Assisted Sperm Analysis data and to fertilizationoutcome, after assisted reproductive techniques. These data havethe potential value to add diagnostic tools to help predict the successof different reproductive techniques.