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Role of cell replication in regulation of Na-coupled hexose transport in LLC-PK/sub 1/ epithelial cells

Technical Report ·
OSTI ID:5526213
The glucose concentration in growth medium has been shown to regulate the number of sodium-coupled glucose transporters in LLC-PK/sub 1/ epithelial cells. Epithelia grown in high concentrations of glucose express fewer transporters than epithelia grown in low concentrations of glucose. In this present work, the effect of a dose of ionizing radiation sufficient to block the incorporation of thymidine was examined in order to gauge the importance of cell replication in the hexose-transport regulatory process. The low rate of thymidine incorporation in the plateau phase was completely eliminated by ionizing radiation. Under conditions of irradiation that completely blocked thymidine incorporation, down-regulation, namely the loss of alpha-methylglucoside-concentrating capacity, brought about by switching the epithelium from low to high glucose-containing medium, is independent of the irradiation and therefore most likely is also independent of cell replication. In contrast, the up-regulatory phenomenon is strongly impaired by radiation. This impairment may be due to specific radiation impairment of gene expression necessary for the up-regulatory process. It is apparent from the dose-response data that up-regulation is not inhibited by irradiation in a simple manner and is not inhibited at the same radiation dose as cell replication.
Research Organization:
Armed Forces Radiobiology Research Inst., Bethesda, MD (USA)
OSTI ID:
5526213
Report Number(s):
AD-A-166858/1/XAB
Country of Publication:
United States
Language:
English