MODIFICATION OF RAT THYMOCYTE MEMBRANE PROPERTIES BY HYPERTHERMIA AND IONIZING-RADIATION

被引:40
作者
LIN, PS
KWOCK, L
HEFTER, K
WALLACH, DFH
机构
[1] Tufts-New England Medical Center, Therapeutic Radiology Department, Radiobiology Division, Boston, MA, 02111
关键词
D O I
10.1080/09553007814550271
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
Thymocytes are one of the most widely used cell models for the study of radiation-induced interphase death. This cell-type was chosen for the study of hyperthermic and radiation effects on two membrane-related processes implicated in the interphase death of cells: Na+-dependent 2-aminoisobutyric acid (AIB) transport and cyclic 3'ndash;5' adenosine monophosphate formation. The response of AIB transport to heat is dose-dependent, but the biphasic thermal response curve (AIB uptake versus time) differs from the sigmoidal radiation response curve. Heating thymocytes for 20-30 min at 43°C stimulates AIB uptake. Additional heating at 43°C, however, markedly reduces AIB uptake. Despite the immediate stimulating effect of heat (30 min at 43°C), the thymocyte has already developed irrepairable impairments, as demonstrated by the fractionated heating experiments. The heat-induced impairment of AIB uptake is mainly on the Na+-dependent component of neutral amino-acid transport, affecting primarily the maximal rate of uptake, i.e. Vmax. Additional evidence for heat-induced plasma membrane damage is the alteration in cAMP levels. Heating thymocytes for 30 min or longer at 43°C causes a massive rise in cAMP level within the cell. This differs from thymocytes exposed to radiation where no rise in cAMP is observed. © 1978 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
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页码:371 / 382
页数:12
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