The present experiment was undertaken to investigate the calcium metabolism in early embryogenesis of rat by measuring the change of free calcium and calmodulin concentration in preimplantation embryos. The concentration of free calcium and
calmodulin
in embryos was measured respectively by using free calcium indicator, fluo-3/AM, and FITC-conjugated biotin with microscope fluorescence spectrometer (excitation wavelength: 450~490mm, emission wavelength: 520mm).
@ES The results obtained were as follows; @EN The concentration of free calcium n embryo was increased in 5hours (78.3±2.0nM) after fertilization when the fertilized egg was activating. The concentration of free calcium in embryos was increased
at
interphase of cell cycle in 25 hours (78.7±3.6nM) and 30 hours (79.9±3.0nM), and also 50 hours (96.8±6.1nM) after fertilization. The concentration of free calcium in embryos was increased at mitotic phase of cell cycle in 20 hours
(76.4±9.1nM),
40
hours (77.9±6.5nM), 45 hours (92.7±2.6nM), and 60 hours (97.0±4.9nM) after fertilization. The concentration of free calcium in embryos was increased in 75 hours (86.9±8.3nM), when 8-cell embryo was compacted and increased in 90 hours
(100.6±5.5nM)
when morula embryo developed to blastocyst. The relative content of calmodulin in embryo was increased in 5 hours (34.1±1.8) after fertilization when the fertilized egg was activating. The relative content of calmodulin in embryos was increased
at
interphase of cell cycle in 10 hours (38.1±1.8), 25 hours (26.4±1.4) and 30 hours (30.3±2.0) after fertilization, and also at mitotic phase of cell cycle in 20 hours (24.5±1.7), 45 hours (27.6±1.2) and 60 hours (25.7±2.1) after
fertilization.
The
relative content of calmodulin in embryo was increased in 75 hours (27.0±2.6) when 8-cell embryo compacted. The change of free calcium and calmodulin concentration in preimplantation embryos showed a similar tendency, but it was different in 10
hours,
50 hours, 65 hours, and 90 hours after fertilization. The present results indicate that increase of free calcium and calmodulin occur more than one time in each cell cycle of fertilized oocyte and preimplantation embryos. Increase of free calcium
and
calmodulin is needed at interphase and mitotic phase in each cell cycle, 8-cell embryo compaction, and increase of free calcium is needed in early blastocyst formation.
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