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. This evidence concerns the gene PKD2 and autosomal dominant polycystic kidney disease.