THERMOSENSITIVITY OF THE MEMBRANE-POTENTIAL OF NORMAL AND SIMIAN VIRUS-40-TRANSFORMED HAMSTER LYMPHOCYTES

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (1) , 209-215
Abstract
The effects of temperature in the fever range (37.degree.-42.degree. C) on the membrane potentials of normal and SV 40-transformed hamster lymphocytes were analyzed. The transmembrane distributions of radiolabeled triphenylmethylphosphonium and thiocyanate were measured, and they provided upper and lower limits for the normal cell membrane potential at 37.degree. C of -48 .+-. 6 (SD) and -31 .+-. 5 mV and for the tumor cells, -36 .+-. 4 and -19 .+-. 2 mV. The mitochondrial contribution to the triphenylmethylphosphonium-measured membrane potential, 5-10 mV for splenocytes and SV 40-transformed lymphocytes, was estimated by utilizing antimycin A and carbonylcyanide-m-chlorophenylhydrazone to inhibit generation of a mitochondrial membrane potential. Incubation for 1-2 h at 38.degree.-42.degree. C resulted in a 6-15 mV depolarization of normal cells and a 2-6 mV hyperpolarization of tumor cells. Depolarization and hyperpolarization were fully reversible by subsequent incubation at 37.degree. C and insensitive to antimycin A and carbonyl-cyanide-m-chlorophenylhydrazone. The membrane potential of normal splenocytes when measured with triphenylmethylphosphonium at 37.degree. C was depolarized by 35% with 1 mM ouabain and thermally induced depolarization was blocked. The membrane potential of tumor cells at 37.degree. C was insensitive to ouabain; the hyperpolarization at 40.degree. C was inhibited. The membrane potential of normal lymphocytes stimulated with phytohemagglutinin was depolarized relative to that of nonstimulated control cells and assumed the thermal response characteristics of tumor cells. [These results are discussed relative to metabolism of antitumor drugs.].