Nephrotic Syndrome

Cortical collecting ducts comprise of two cell types - principal cells and intercalated cells. Principle cells allow sodium and water reabsorption and potassium secretion while intercalated cells account for proton, bicarbonate and chloride transport. Click here for more information on the intercalated cell.

Sodium reabsorption takes place in two steps:

1. The Na⁺K⁺ATPase actively pumps sodium from the basolateral surface of the principle cell.
2. The electrochemical gradient created facilitates the passive entry of sodium through selective sodium channels (ENaC)

Aldosterone stimulates synthesis of the epithelial sodium channel (ENaC) and Na⁺K⁺ATPase. The ENaC is blocked by amiloride. However hyperaldoseronism is not necessary for sodium retention in PAN-nephrotic rats as oedema accumulates in adrenalectomised animals.

Other factors which may be involved in sodium retention.