<prompt> The Principal site of absorption of sodium isProximal convoluted tubuleDistal convoluted tubuleLoop of Henle thick portionCollecting duct  <response>: Other than at thin descending limb of the loop of Henle, all other sites of tubule Na are reabsorbed by various mechanisms. - Proximal tubule- 60-70Na- H exchangeNa- Glucose co-transportNa- amino acid co-transportNa unitransport- The thick ascending limb of the loop of Henle - 30Na- 2Cl-- K co-transport- Early distal tubule- 7Na- Cl- co-transport- Late distal tubule and collecting duct - 3ENaC channels 