Editing Countercurrent exchange (section)

==== History ====
Initially the countercurrent exchange mechanism and its properties were proposed in 1951 by professor [[Werner Kuhn (chemist)|Werner Kuhn]] and two of his former students who called the mechanism found in the [[loop of Henle]] in mammalian [[kidneys]] a Countercurrent multiplier<ref>The original lecture was published in 1951 in German. [http://www.isbnlib.com/preview/1859734219/ According to a book on Jewish scientists under the Reich] Kuhn theorized and studied this mechanism already in the early 1940s. This was confirmed in 2001 in [http://jasn.asnjournals.org/content/12/7/1566.full.pdf the translation to the original lecture] published with remarks by Professor Bart Hargitay, then one of the two former student aids. Harbitay says: Before settling in Basel, Kuhn did some very fundamental work in Kiel, separating isotopes in a centrifuge. This caused him to be fascinated with the effect of countercurrents in multiplying a very small single effect to significant separations. (Journal of the American Society of Nephrology website)</ref> and confirmed by laboratory findings in 1958 by Professor [[Carl W. Gottschalk]].<ref>{{citation|last1=Gottschalk|first1=C. W.|author1-link=Carl W. Gottschalk|first2=M.|last2=Mylle|title=Evidence that the mammalian nephron functions as a countercurrent multiplier system|journal=Science|volume=128|issue=3324|year=1958|page=594|doi=10.1126/science.128.3324.594|pmid=13580223|bibcode=1958Sci...128..594G|s2cid=44770468}}.</ref> The theory was acknowledged a year later after a meticulous study showed that there is almost no osmotic difference between liquids on both sides of nephrons.<ref>{{citation|last1=Gottschalk|first1=C. W.|author1-link=Carl W. Gottschalk|first2=M.|last2=Mylle|title=Micropuncture study of the mammalian urinary concentrating mechanism: evidence for the countercurrent hypothesis|journal=American Journal of Physiology|volume=196|issue=4|pages=927–936|year=1959|pmid=13637248|doi=10.1152/ajplegacy.1959.196.4.927|doi-access=}}. See also [http://www.nature.com/ki/journal/v31/n2/abs/ki198729a.html History of the urinary concentrating mechanism] an article in 'Kidney'—the ''Journal of International Society of Nephrology'', where Prof. Gottschalk points to the heated debate prior to the acceptance of the theory of the countercurrent multiplier action of the kidney</ref> [[Homer W. Smith|Homer Smith]], a considerable contemporary authority on renal physiology, opposed the model countercurrent concentration for 8 years, until conceding ground in 1959.<ref name= HomerSmith>Smith, Homer W., The fate of sodium and water in the renal tubules, Bull. New York Academy of Medicine 35:293–316, 1959.</ref> Ever since, many similar mechanisms have been found in biologic systems, the most notable of these: the [[rete mirabile]] in fish.