<prompt> The Principal site of absorption of Sodium is :Proximal convoluted tubuleDistal convoluted tubuleLoop of Henle thick poionCollecting duct  <response>: A i.e. Proximal convoluted tubuleNormally about 60 of the filtered Na is reabsorbed in the proximal tubuleQ.Sodium ReabsorptionPercentageSite60Proximal tubuleQ by N a - H exchange30Thick ascending limb by Na - 2C1 - K cotranspo7Distal convoluted tubule by Na - Cl- cotranspo3Collecting duct. ENaC channels 