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Changes in the Activities of H + , K + ‐ATPase and Na + , K + ‐ATPase in Cultured Cells Derived from Micromeres of Sea Urchin Embryos with Special Reference to Their Roles in Spicule Rod Formation
Author(s) -
Mitsunaga Keiko,
Fujiwara Akiko,
Fujino Yukio,
Yasumasu Ikuo
Publication year - 1989
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1989.00171.x
Subject(s) - spicule , sponge spicule , atpase , ouabain , sea urchin , biology , cell culture , embryo , chemistry , microbiology and biotechnology , anatomy , biophysics , biochemistry , enzyme , sodium , genetics , organic chemistry
In cultured cells derived from micromeres isolated at the 16‐cell stage of sea urchin embryos, the activity of H + , K + ‐ATPase became detectable after 15 hr of culture, when the cells started to form spicules, and then increased reaching a plateau from 25 hr of culture. The Na + , K + ‐ATPase activity of isolated micromeres increased to a maximum at 20 hr of culture and thereafter decreased gradually. Allylisothiocyanate, an inhibitor of H + , K + ‐ATPase, caused a decrease in intracellular pH (pHi) accompanied by blockage of 45 Ca deposition in spicule rods in spicule‐forming cells at 30 hr of culture. Ouabain and amiloride had scarcely any effect on the pHi or 45 , deposition. In cultured cells exposed to nifedipine, which blocked 45 Ca deposition in spicule rods, allylisothiocyanate did not cause any decrease in pHi. These results show that H + , which is generated in the overall reaction to produce CaCO 3 from Ca 2+ and HCO 3 − , is probably released from the cells mainly in the reaction catalyzed by H + , K + ‐ATPase to maintain successive production of CaCO 3 .