Sodium and Potassium Distribution in Isolated Thymus Nuclei

¹ From The Rockefeller Institute, New York City

Calf thymus nuclei isolated in nonaqueous media contained 238 µEq of sodium and 661 µEq of potassium/gm dry weight; calf thymus nuclei isolated in sucrose solution contained 87 ± 4.8 (S.E.) µEq of sodium and 244 ± 12.2 µEq of potassium/gm dry weight. In a series of experiments designed to survey the influence of various factors on the sodium and potassium contents of thymus nuclei isolated in sucrose, sodium proved to be the more stable constituent. Potassium was lost easily from the nuclei on prolonged standing at low temperature, on repeated washings, after incubation in potassium free media, particularly in the presence of pyridoxal, Hg⁺⁺, phenol, m-cresol and urea. Chloroform extracts and TCA precipitates of the nuclei contained 7% and 30%, respectively, of the nuclear sodium, but no potassium.