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Interaction between injected Ca 2+ and intracellular Ca 2+ stores in Xenopus oocytes
Author(s) -
Dascal Nathan,
Boton Rony
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80278-q
Subject(s) - ionophore , xenopus , intracellular , long term potentiation , biophysics , chemistry , oocyte , membrane , calcium , membrane potential , biochemistry , biology , microbiology and biotechnology , embryo , receptor , gene , organic chemistry
Upon two repetitive deep injections of Ca 2+ into Xenopus oocyte (200–300 μn under the membrane), the amplitude of the transient Cl − current induced by the second injection is several‐fold higher than that of the first one. This ‘potentiation’ persists even at 60–90 min intervals between injections. However, in oocytes permeabilized to Ca 2+ by the ionophore A23187 in a Ca 2+ ‐free solution, the potentiation completely disappears after 30 min. It is proposed that the injected Ca 2+ is largely taken up by the stores, whereas following the second injection, a higher proportion of Ca 2+ reaches the membrane, since the stores are already loaded. In ionophore‐treated oocytes, the stores lose the accumulated Ca 2+ over several minutes and are then ready to take up Ca 2+ again, hindering its arrival at the membrane.