UPTAKE OF TRITIUM-LABELED ADENOSINE TRIPHOSPHATE BY THE CYTOPLASM OF FIXED INTERSTITIAL CELLS FROM RAT TESTES

The cytoplasm of histologically fixed interstitial cells of rat testes becomes heavily labeled after incubation in the presence of tritium-labeled adenosine triphosphate. The phenomenon shows a high degree of specificity; none of the other eight types of cells studied (five of nontesticular origin) exhibits significant labeling under the same conditions. The cell labeling seems to be nonenzymatic in character; specific macromolecules associated with retention of the label have not been identified. Label retained by the cytoplasm of interstitial cells withstands: (a) prolonged washings in cold 5% trichloroacetic acid; (b) washings in a solution of high ionic strength; (c) repeated washings with alcohol and with water; (d) heating to 100°C; and (e) treatment with enzymes hydrolyzing nucleic acids (deoxyribonuclease I, ribonuclease A, ribonuclease T 2 , micrococcal nuclease and phosphodiesterase).