Effects of platinic chloride on Tetrahymena pyriformis GL

The effects of 0.2-2.0 mM PtCl(4) have been investigated, the purpose was to test whether the compound would affect Tetrahymena in a manner similar to that of cis-dichlorodiammine-platinum(II), or cisplatin, which in 0.83 mM inhibits cell proliferation for 24 h and induces diminution of the inner mitochondrial membrane, as reported recently. During the first hour, the rate of cell proliferation was unaffected by platinic chloride; this period was followed by a lag of 1-1.5 h in 0.5-0.83 mM, of 5 h in 1.0 mM, and of about 24 h in 1.5-2.0 mM PtCl(4) before proliferation resumed at a decreased, but constant, rate. At the low concentrations, the rate of proliferation corresponded to half the rate of control cells, whereas only 1.00 and 0.56 cell doubling was completed after 24 h in 1.5 and 2.0 mM, respectively, and a large percentage of the cells were monsters. The normal cell shape was restored within 48 h. The rate of endocytosis was affected dose dependently, but not blocked completely in 0.5-2.0 mM PtCl(4). All treated cells contained small refractive granules, accumulating with time in growth-inhibited cells but remaining at a constant level in cells capable of proliferation. These granules are probably connected with cell detoxification as proposed previously. In contrast to cisplatin, PtCl(4) did not induce loss of the inner mitochondrial membrane, even after 24 h in 2.0 mM.