Effect of inositol and glycine with increasing sodium chloride and constant osmolality on development of rabbit embryos

Purpose: Many commercially available culture media have a high sodium content as sodium chloride and sodium bicarbonate. We examined the effects of osmolytes, inositol and glycine, on embryos cultured in synthetic RD medium with a lower concentration of NaCl (93 mM) and a higher concentration of NaCl (116 mM) with media held constant at 270 mosmols. Results: There were no significant effects of either glycine or inositol on embryo growth when the embryos were cultured in RD medium with 93 mM NaCl (P>0.05). Culture of one-cell embryos for 72 h in RD medium with 93 mM NaCl, 116 mM NaCl and 116 mM NaCl containing 0.56 mM inositol resulted in 77%, 14% and 55% expanded blastocysts, respectively (P<0.05). Corresponding values for two-cell embryos cultured for 67 h were 84%, 34% and 66% expanded blastocysts (P<0.05). When one-cell and two-cell embryos were cultured in RD medium with 93 mM NaCl, 116 mM NaCl, 116 mM NaCl plus 1 mM glycine and 116 mM NaCl plus 1 mM glycine and 0.56 mM inositol, expanded blastocysts from one-cell embryos were 79%, 19%, 49%, and 48%, respectively (P <0.05), and expanded blastocysts from two-cell embryos were 91%, 32%, 52%, and 53%, respectively (P<0.05). Conclusion: Inositol and glycine presumably behave as osmolytes in providing substantial protection for rabbit one-cell and two-cell embryos cultured in a medium with high NaCl concentration.