<prompt> Answer this question truthfullyWhat is the cause of the unresponsiveness of the principal cells of the collecting duct to ADH in nephrogenic diabetes insipidus?  <response>: <reason> In nephrogenic diabetes insipidus, the principal cells of the collecting duct are unresponsive to ADH due to a defect in the V2 receptor, Gs protein, or adenylyl cyclase. 