Ionomycin is a selective and potent calcium ionophore, which acts as a motile Ca2+ carrier.by direct stimulation of store-regulated cation entry across biological membranes, ionomycin can effectively enhance Ca2+ influx.

In vitro: Calcium ion can be extracted by ionomycin fom the queous phase into the organic phase. Ionomycin also acts as a mobile ion carrier, which transports the cation across a solvent barrier [1].

In vivo: Efficiency of ionomycin on oocyte activation and subsequent development was evaluated, which identified ionomycin as an efficient activator at the concentation of 10 μmol/l. With a second exposure to 5 μmol/l ionomycin on blastocyst development, an improved effect was found. No adverse effects of ionomycin on mouse embryo development were identified [2].

Clinical trial: One randomized, prospective, controlled study has been performed to analyze the effect of calcium ionophore solution on fertilization rate in patients with diminished ovarian reserve, which did not observe any differences in fertilization, clinical pregnancy, or ongoing pregnancy rates between the groups [3].

References:
[1] Liu C, Hermann TE.? Characterization of ionomycin as a calcium ionophore. J Biol Chem. 1978 Sep 10;253(17):5892-4.
[2] Heytens E, Soleimani R, Lierman S, De Meester S, Gerris J, Dhont M, Van der Elst J, De Sutter P.? Effect of ionomycin on oocyte activation and embryo development in mouse. Reprod Biomed Online. 2008 Dec;17(6):764-71.
[3] Caglar Aytac P, Kilicdag EB, Haydardedeoglu B, Simsek E, Cok T, Parlakgumus HA.? Can calcium ionophore "use" in patients with diminished ovarian reserve increase fertilization and pregnancy rates A randomized, controlled study. Fertil Steril. 2015 Nov;104(5):1168-74.