DEOXYCYTIDINE KINASE AND CYTOSINE NUCLEOSIDE DEAMINASE ACTIVITIES IN SYNCHRONIZED CULTURES OF NORMAL RAT-KIDNEY CELLS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (9) , 2768-2772
Abstract
Previous work suggested that 1-.beta.-D-arabinofuranosylcytosine [ara-C]-5''-triphosphate is the active metabolite of 1-.beta.-D-arabinofuranosylcytosine [ara-C, an antineoplastic drug]. The amount of ara-C-5''-triphosphate formed in tissues is influenced by the relative levels of deoxycytidine kinase and cytosine deaminase. The intracellular levels of deoxycytidine kinase and cytosine deaminase activities were measured in synchronized cultures of normal rat kidney [NRK] cells. The deoxycytidine kinase activity was cell cycle related with a minor peak of activity in early G1 phase and a major peak of activity in middle and late S phase. The cytosine deaminase activity was also cycle dependent with a peak of activity at G1 phase and another at S phase of the cell cycle. Similar results were obtained when cytosine deaminase activities were measured with cytidine, deoxycytidine or ara-C. The main effect of ara-C was in the late S phase of the cell cycle.