Lithium-induced nephrogenic diabetes insipidus is a clinical condition that can arise in patients receiving lithium therapy for bipolar disorder. Lithium ions enter the principal cells of the collecting duct and directly inhibit the intracellular enzyme adenylate cyclase. Under normal physiological conditions, this enzyme is activated following the binding of antidiuretic hormone (ADH) to its receptor.
Explain how this inhibition of adenylate cyclase affects the translocation of aquaporins and the subsequent water potential of the urine produced.
State and explain one physiological symptom or clinical sign a patient with this condition would exhibit.
17 exam-style questions on OCR A A Level Biology Excretion as an example of homeostatic control. Each one has a worked solution and a mark scheme showing where the marks go.