This is the final paragraph in the discussion section of the paper by Skulachev, regarding the use of a Na+/K+ concentration gradient across a membrane to store potential energy, convertible to a Na+ or H+ gradient as needed, and why elevated K+ does not have to be a primordial feature of proto-cells:
"One might think that Na+ ions are incompatible with life and this is the reason why K+ is substituted for Na+ in the cell interior. Apparently, it is not the case as, e.g., in halophilic bacteria [Na+]int can reach 2 M [41]. The very fact that some enzyme systems work better in the presence of K+ than of Na+, may be considered as a secondary adaptation of enzymes to the K+-rich and Na+-poor conditions in the cytosol [40]. Besides, it would have been dangerous to couple any work performance with Na+ influx to the cytoplasm if Na+ were a cell poison".
That makes perfect sense to me.
Peter
https://www.scientificamerican.com/article/records-found-in-dusty-basement-undermine-decades-of-dietary-advice/?WT.mc_id=SA_WR_20170426
ReplyDeletePeter-I read this and thought you might like to see it if you havent already.
Thanks Judith, a classic on a classic!
ReplyDeletePeter
Peter, I wondered whether you might find these two studies, recently published in The Journal of Clinical Investigation, of interest. (1) High salt intake reprioritizes osmolyte and energy metabolism for body fluid conservation and (2) Increased salt consumption induces body water conservation and decreases fluid intake.
ReplyDeleteA New York Times article, "Why Everything We Know About Salt May Be Wrong," published on May 8th provides a decent summary. There are links to the papers in the NYT's article. Both are open access.
https://www.nytimes.com/2017/05/08/health/salt-health-effects.html
Thanks Jacquie,
ReplyDeleteOn the to-read list!
Peter