THERMOTOLERANCE IN CHICKEN RED-BLOOD-CELLS STUDIED BY P-31 NMR-SPECTROSCOPY

Chicken red bloods cells (RBCs) were used as a model for cell survival following hyperthermia of differentiated cells, with rat RBCs serving as controls. The purpose was to investigate whether cells heated at 5 1.5 degrees C with or without prior heat shock exhibited discernible d ifferences in phosphorus metabolites, intracellular pH or Mg2+ using P -31 nuclear magnetic resonance spectroscopy. The biochemical differenc es that distinguished the heat-shocked from the non-heat-shocked chick en cells were: (1) a decrease in intensity of the low and wide (300 Hz ) resonance that underlies the high resolution signals and which arise s from the partially mobile membrane phospholipids, suggesting that me mbrane fluidity was decreased during the induction of thermotolerance; and (2) a time-dependent leftward shift of the peak representing the 4,6P of inositol pentaphosphate together with a broadening of all of t he P-31 peaks during heat-shock and heat challenge, which persisted af ter return to the control temperature. This is consistent with signifi cant oxygen consumption in the heat-shocked but not the non-heat-shock ed cells, We conclude that chicken RBCs are capable of specific metabo lic and physiologic responses to heat shock, as expected in cells know n to produce heat-shock proteins and to be capable of thermotolerance induction.