Thermotolerance in chicken red blood cells studied by 31P 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 51.5 degrees C with or without prior heat shock exhibited discernible differences in phosphorus metabolites, intracellular pH or Mg2+ using 31P nuclear magnetic resonance spectroscopy. The biochemical differences that distinguished the heat-shocked from the non-heat-shocked chicken cells were: (1) a decrease in intensity of the low and wide (300 Hz) resonance that underlies the high resolution signals and which arises from the partially mobile membrane phospholipids, suggesting that membrane 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 the 31P peaks during heat-shock and heat challenge, which persisted after return to the control temperature. This is consistent with significant oxygen consumption in the heat-shocked but not the non-heat-shocked cells. We conclude that chicken RBCs are capable of specific metabolic and physiologic responses to heat shock, as expected in cells known to produce heat-shock proteins and to be capable of thermotolerance induction.