Effects of Heat and of Ultrasound on Terminally-Differentiated Cells: The Erythrocyte as a Model System
Kozma, Thomas George
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https://hdl.handle.net/2142/72565
Description
Title
Effects of Heat and of Ultrasound on Terminally-Differentiated Cells: The Erythrocyte as a Model System
Author(s)
Kozma, Thomas George
Issue Date
1992
Doctoral Committee Chair(s)
Ducoff, H.S.,
Department of Study
Physiology and Biophysics
Discipline
Physiology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Radiology
Biophysics, Medical
Abstract
The effects of heat and of ultrasound were investigated in the terminally- differentiated erythrocyte using hemolysis as end-point. The heat-induced hemolysis of chicken and rat red blood cells (RBC's) was determined between 45 and 51.5$\sp\circ$C. Rat RBC's were more heat sensitive than chicken RBC's. Survival following split-heating was the same as survival following continuous heating when the interval between heatings was 20 min, while survival decreased steadily as this interval was increased to 50 hr.
Induction of thermotolerance occurred in chicken RBC's after chronically heating cells at 42.4$\sp\circ$C for 2 hr. Induction of thermotolerance in fresh rat RBC's was not achieved.
$\sp{31}$P NMRS was used to monitor changes occurring in the phosphorus metabolites of chicken RBC's during heating. No differences occurred in the levels of nucleoside triphosphates to differentiate heat-shocked RBC's from non-heat-shocked RBC's. The intracellular pH of RBC's changed significantly with temperature, but was the same at a given temperature in both heat-shocked and non-heat-shocked cells.
Differences were found between the spectra of heat-shocked and non-heat-shocked RBC's. The spectral line widths of heat-shocked cells were significantly broadened during heat shock and 51.5$\sp\circ$C challenge indicating that hemoglobin became deoxygenated. In addition, a time-dependent left-ward shift of the peak representing the 4,6-P of inositol pentaphosphate occurred during heat shock and remained significantly shifted 0.419 ppm to the left when cells were returned to 23$\sp\circ$C. This suggests that the oxygen-hemoglobin affinity may be reduced in RBC's undergoing a heat shock.
Investigations using ultrasound (U.S.) to induce hemolysis showed that damage produced by U.S. could be monitored using the RBC and compared to the damage produced by heat; however, RBC's were not sensitive enough to use for detecting damage at clinically relevant intensities. The rate and kinetics of damage following either modality were significantly different indicating that the two modalities acted on different targets or affected the same targets differently. These results suggest that the mechanism of U.S. damage is different from the effects of other physical agents.
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