Influência do bloqueio da Na+, K+-ATPase em blastocistos equinos

Abstract

Currently, one of the challenges on equine reproduction is the low survival rate of horse embryos cryopreserved with diameter > 300 μm, using either vitrification or classic methods. Researches about the influence of sodium pump and potassium (Na+, K+-ATPase) on horse embryo development have more than 30 years and nowadays it is known that participates on embryo cavitation, changes ionic gradient of trophoblastic cells, as well as influences formation, distribution and permeability of tight junctions (TJ) between trophoblastic cells. Due to many Na+, K+-ATPase isoforms, depending on comprising subunits, as well as peculiarities on embryo development depends on species, this work is characterizied by a literature review to demonstrate the main results in the field of research. It is also presented the results of a study that aimed to develop a medium able to reduce horse embryo diameter in the field, to support horse blastocyst vitrification. Horse embryos were hasvested and subjected to Na+, K+-ATPase inhibition for 1 or 6 h, using ouabain isolated or conjugates to fluorescent probe (OuabaínaFL), during incubation at 37 ° C. Embryos were assessed for morphometric characteristics (bright field microscopy) and viability (Hoechst 33342 + propridium iodide). To our knowledge, this is the first study that primarly aimed to evaluate the influence of Na+, K+-ATPase inhibition with ouabain, a specific inhibitor, on the horse embryos. It was observed that Na+, K+-ATPase inhibition with ouabain is able to reduce horse blastocyst diameter, in spite of embryo development (D7 ou D9), and ouabain binding to blastocysts were confirmed after embryo exposition to fluorescent conjugated ouabain. However, Na+, K+-ATPase inhibiton compromised embryo viability and it is not recommended as a strategy to reduce horse blastocyst diameter.