Vasopressin V2 receptor antagonists OPC-31260 and its derivative tolvaptan (OPC-41061) have for example shown effectiveness in several distinct rodent models of PKD, among those the PCK rat, the pcy mouse, the Pkd2 WS25 mouse, and a conditional kidney specific Pkd1 knock-out model [205,206,207,208], as well as in the cpk mouse [209], a model of autosomal recessive PKD (ARPKD), before and while clinical testing for its effectiveness in ADPKD treatment was conducted. The gene discussed is PKD2; the disease is autosomal recessive polycystic kidney disease.