Inhibition of Protein Synthesis by Reduced K(superscript +)in Cultured Endothelial Cells

Sio-Leng Leong；Wei-Ching Ma；Mei-Chuan Chen；Ying-Tung Lau

endothelial cell ； protein synthesis ； intracellular K(superscript +) ； ouabain

The Chinese Journal of Physiology

40卷3期（1997 / 09 / 01）

143 - 148

英文

Total protein synthesis (as precipitable [(superscript 3)H] leucine incorporation) was determined under various experimental conditions to examine the relationship between cellular K(superscript +) and protein synthesis in human umbilical vein endothelial cells (HUVEC). We found that under normal external K(superscript +) concentration (5mM), total protein synthesis was inhibited by cycloheximide and ouabain, with estimated values of IC50 of 0.41μM and 0.60mM, respectively. Cellular K(superscript +) concentrations were determined (102±4mM for control cells) and found to be significantly increased (P＜0.01) by high external K(superscript +) (25mM) and significantly decreased (P＜0.001) by low external K(superscript +) (0.5mM) as well as by ouabain (2mM). Under high external K(superscript +), total protein synthesis and the inhibitory responses of cycloheximide and ouabain were not altered. On the contrary, cellular K(superscript +) and protein synthesis were both further reduced by about half (P＜0.001) under low external K(superscript +). While ouabain further reduced cellular K(superscript +) by half (P＜0.001), protein synthesis was only slightly reduced (P＜0.05) under low external K(superscript +) and thus the relative reduction on protein synthesis was much less than that for cellular K(superscript +). These results indicate that while elevated intracellular K(superscript +) did not alter protein synthesis, reduced intracellular K(superscript +) correlated with a reduced cellular protein synthesis in HUVEC such that K(superscript +) may play a permissible role in the regulation of protein synthesis.