| Abstrakt: |
Mg, Ca, Mn, Zn, and Cu content of neurons from chick embryo cortex cultivated in chemically defined serum free growth medium was determined by energy dispersive X-ray fluorescence and atomic absorption spectroscopy. The intracellular volume of cultured neurons was determined to be 2.73 μl/mg. Intracellular Mn, Fe, Zn, and Cu in the cultivated neurons were 100-200 times the concentrations in the growth medium: Mg and Ca were 0.9 and 1.7 mM respectively, around 20 fold higher than in growth medium. Mg, Fe, Cu and Zn concentrations in neurons were in the range of ca. 300-600 μM, approximately 2-3 times the values previously reported in glial cells; Ca and Mn content of the neurons were higher by 5 and 10 fold respectively compared to glial cells. In neurons, the subcellular distribution of Fe, Cu, and Mn follows the rank order: cytosol>microsomes>mitochondria; for Zn the distribution differs as following: cytosol >mitochondria>microsomes. Determination of the superoxide dismutase activities in the cultivated neurons indicated that the Mn linked activity predominates whereas, the Cu-Zn dependent enzyme is dominant in glial cells. Enrichment of the culture medium with Mn to 2.5 μM enhanced the Mn-SOD by approximately 33% but Cu−Zn enzyme activity was not modified. The high Mn content, the capacity to accumulate Mn, and the predominancy of the Mn−SOD form observed in neurons is in accord with a fundamental functional role for this metal ion in this type of brain cells. [ABSTRACT FROM AUTHOR] |
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