Acquired NDI
Acquired NDI is the consequence of several conditions (Table 2) that are characterized by an increased water output and reduced urine osmolality, despite elevated levels of AVP. In many of these conditions, the kidney is unable to handle water due to an impaired responsiveness to vasopressin. As discussed below, a number of rat models with NDI have been evaluated, and common for all is a reduced expression of AQP2 in the principal cells of the collecting ducts. However, as is discussed, the degree of AQP2 downregulation as well as the intracellular localization of the protein differs significantly among the various conditions, suggesting that different mechanisms are responsible for AQP2 dysregulation in the various models. In addition to DI, a few other serious conditions are associated with reduced AQP2 levels and urinary concentrating defects (see Table 2).
1. Lithium-induced NDI
Lithium administration is a very common treatment of manic-depressive disease. It......
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