title: Inhibition of protein synthesis by reduced K+ in cultured endothelial cells.
abstract: Total protein synthesis (as precipitable [3H] leucine incorporation) was determined under various experimental conditions to examine the relationship between cellular K+ and protein synthesis in human umbilical vein endothelial cells (HUVEC). We found that under normal external K+ concentration (5 mM), total protein synthesis was inhibited by cycloheximide and ouabain, with estimated values of IC50 of 0.41 microM and 0.60 mM, respectively. Cellular K+ concentrations were determined (102 +/- 4 mM for control cells) and found to be significantly increased (P < 0.01) by high external K+ (25 mM) and significantly decreased (P < 0.001) by low external K+ (0.5 mM) as well as by ouabain (2 mM). Under high external K+, total protein synthesis and the inhibitory responses of cycloheximide and ouabain were not altered. On the contrary, cellular K+ and protein synthesis were both further reduced by about half (P < 0.001) under low external K+. While ouabain further reduced cellular K+ by half (P < 0.001), protein synthesis was only slightly reduced (P < 0.05) under low external K+ and thus the relative reduction on protein synthesis was much less than that for cellular K+. These results indicate that while elevated intracellular K+ did not alter protein synthesis, reduced intracellular K+ correlated with a reduced cellular protein synthesis in HUVEC such that K+ may play a permissible role in the regulation of protein synthesis.
authors.affiliation: Department of Physiology, Chang Gung University College of Medicine, Taoyuan, Taiwan, ROC.
authors.forename: S L
authors.initials: SL
authors.lastname: Leong
authors.forename: W C
authors.initials: WC
authors.lastname: Ma
authors.forename: M C
authors.initials: MC
authors.lastname: Chen
authors.forename: Y T
authors.initials: YT
authors.lastname: Lau
mesh_terms: D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007930:Leucine / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000502:physiology*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors
chemical_list: D011500:Protein Synthesis Inhibitors; D010042:Ouabain; D003513:Cycloheximide; D007930:Leucine; D011188:Potassium