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Influence of exogenous ions on the events of maturation in Rana pipiens oocytes
Author(s) -
Ecker R. E.,
Dennis Smith L.
Publication year - 1971
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040770108
Subject(s) - divalent , chemistry , kinetics , oocyte , compartment (ship) , biophysics , ionic strength , ionic bonding , ion exchange , endogeny , biochemistry , microbiology and biotechnology , ion , embryo , biology , physics , oceanography , organic chemistry , quantum mechanics , geology , aqueous solution
Full‐grown ovarian oocytes removed from non‐hormone‐treated Rana pipiens females exhibit a low level of protein synthesis, the rate of which is dependent upon the ionic environment. The highest rates of protein synthesis in these oocytes are obtained in media containing either a divalent cation (Ca ++ or Mg ++ ) or high levels of K + . The dependence of protein synthesis on ionic environment persists through about the first 18‐24 hours of maturation (at 18°C). Normal maturation of oocytes in vitro also has specific ionic requirements for the first 24 hours. In this case, the process requires high ionic strength (T/2 = 1.0‐1.2) and divalent cations. The kinetics of K + exchange suggest that K + exists in the ovarian oocyte in two compartments; one in equilibrium with the exogenous medium and freely exchangeable; the other in equilibrium with the exogenous medium and freely exchangeable; the other in equilibrium with the first internal compartment and only very slowly exchangeable. The slowly exchangeable (bound) compartment contains about 95% of all endogenous K + . In hormone stimulated oocytes, the kinetics of K + exchange are essentially the same. Oocyte adaptation to ionic environment is discussed as a possible regulatory mechanism during maturation.