Editing Collecting duct system (section)

====Principal cells====
The principal cell mediates the collecting duct's influence on sodium and potassium balance via [[sodium channel]]s and [[potassium channel]]s located on the cell's [[apical membrane]]. [[Aldosterone]] determines expression of sodium channels (especially the [[ENaC]] on the collecting tubule). Increases in aldosterone increase expression of luminal sodium channels.<ref>{{cite journal |last1= May|first1= Anne|last2= Puoti|first2= Alessandro|last3=Gaeggeler|first3=Hans-Peter|last4=Horisberger|first4=Jean-Daniel|last5=Rossier|first5=Bernard C|date= 1997|title= Early Effect of Aldosterone on the Rate of Synthesis of the Epithelial Sodium Channel a Subunit in A6 Renal Cells|url= http://jasn.asnjournals.org/content/8/12/1813.full.pdf|journal= Journal of the American Society of Nephrology|volume= 8|issue= 12|pages= 1813–1822|doi= 10.1681/ASN.V8121813|pmid= 9402082|access-date= 21 November 2017|doi-access= free}}</ref> Aldosterone also increases the number of [[Na⁺/K⁺-ATPase]] pumps <ref name=GUYTON2006>{{Cite book| edition = 11| publisher = Elsevier Saunders| isbn = 0-7216-0240-1| last = Guyton| first = Arthur C.|author2=John E. Hall| title = Textbook of Medical Physiology| location = Philadelphia| year = 2006}}
</ref>{{rp|949}} that allow increased sodium reabsorption and potassium excretion.<ref name=GUYTON2006 />{{rp|336}} [[Vasopressin]] determines the expression of [[aquaporin]] channels that provide a physical pathway for water to pass through the principal cells.<ref>{{cite journal|doi=10.1007/BF00584753|pmid=2441357|title=Electrophysiological studies in principal cells of rat cortical collecting tubules ADH increases the apical membrane Na+-conductance|year=1987|last1=Schlatter|first1=Eberhard|last2=Schafer|first2=James A.|journal=Pflügers Archiv: European Journal of Physiology|volume=409|issue=1–2|pages=81–92|s2cid=24655136}}</ref> Together, aldosterone and vasopressin let the principal cell control the quantity of water that is reabsorbed.