EDTA and Ni2+ have been known to be calcium chelator and calcium channel blocker as well as calcium inhibitor. In addition, these two agents are not permeable to the embryo. This fact suggests that these agents might have some interactions with
the
membrane (plasma membrane) of the embryos, control calcium permeability, calcium concentration in the cytoplasm, calcium metabolism in the embryo and calcium release from intracellular calcium reservoir by signal transduction on the membrane and
that
these two agents might have an indispensable relationship with Ca2+ on the membrane.
In relation with the above suggestion various Ca2+ channel blockers and Ca2+ inhibitors were treated in the culture medium in order to investigate the effect of these blockers and inhibitors on overcoming effect of the mouse 2-cell block in the
present
studies.
@ES We obtained conclusions as following.
@EN 1. Calcium inhibitor, Co2+ showed strong inhibition of development of the embryos and toxin-like effect. So Co2+ seems to be a strong Ca2+ inhibitor.
2. Cd2+ did not show overcoming effect of the 2-cell block at all dosages used for 72 hr culture period. However, Cd2+ showed keeping long viability of 2-cell embryos at lowest dose (10μM).
3. Barium (Ba2+) showed some overcoming effect of 2-cell block at the dose of 1,000μM Ba2+. However, other dosage did not show any difference in the development to morula and blastocyst in comparison with the control group.
4. Strontium (Sr2+) showed some effect of keeping viability of embryos at the dose of 100μM and decreased degeneration rate in comparison with the control. Sr2+ seems to be a very weak Ca2+ inhibitor.
5. Ni2+ was very effective in overcoming of 2-cell block at the dose of 50μM and 100μM for 72 hr culture period. However, in extended culture period (96 hr, data not shown) 100μM Ni2+ seems to be inhibiting hatching process of late blastocyst,
and
increased degeneration at blastocyst without hatching. It is suggested that Ni2+ might be involved in intracellular calcium release from the intracellular calcium reservoirs at early stage of embryos but not in later stages of embryos. Further
studies
on the mechanism of the induction of intracellular Ca2+ concentration increase by Ni2+ needed to be done.
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