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Oscillations and cyclic AMP‐induced changes of the K+ concentration in Dictyostelium discoideum.
Author(s) -
Aeckerle S.,
Wurster B.,
Malchow D.
Publication year - 1985
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1985.tb02314.x
Subject(s) - dictyostelium discoideum , extracellular , biology , biophysics , adenosine , tetraethylammonium , biochemistry , microbiology and biotechnology , potassium , chemistry , organic chemistry , gene
By means of a K+‐sensitive electrode, the extracellular K+ concentration was monitored in cell suspensions of Dictyostelium discoideum. In aggregative cells the attractant cyclic AMP induced a transient release of K+. The response was detectable within 6‐12 s and peaked at 30‐40 s. The apparent rate of release amounted to 7 X 10(8)K+ ions per cell per min. Adenosine and 5′ AMP, which are chemotactically inactive, did not elicit measurable K+ responses. The cyclic AMP‐induced release of K+ depended on the state of differentiation of the cells. In undifferentiated cells cyclic AMP did not cause a measurable K+ release, whereas folic acid, a potent attractant at this cell stage, induced a weak but significant K+ response. The cyclic AMP‐induced K+ release in aggregative cells was inhibited by K+‐channel blockers such as quinine and tetraethylammonium. In suspensions of differentiated cells free running oscillations of the extracellular K+ concentration were observed. K+ oscillations were related to cyclic AMP oscillations and oscillations of the light‐scattering properties of cells. Cells continuously released NH4+; however, cyclic AMP did not induce a measurable change of NH4+ release.