Dev Growth Differ 1989 Apr 01;312:171-178. doi: 10.1111/j.1440-169X.1989.00171.x.

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: (sea urchin egg/development/spicule rod/Na+ , K+ -ATPase/H+ , K+ -ATPase).

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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 CaCO3 from Ca2+ and HCO3 - , is probably released from the cells mainly in the reaction catalyzed by H+ , K+ -ATPase to maintain successive production of CaCO3 .

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