NPPA and Polyuria: However, recent studies have shown that AVP, ANP and their associated receptors, V2R and NPRA, plus water channel AQP2 and ENaC, are significantly altered after SCI in rats.8,9 The significant decrease in AVP, specifically at night, has also been shown in the clinical setting.12,43 Together, the changes in these hormone peptides/receptors are in the direction that would indicate an increase in urine production and require further investigation for the elucidation of SCI-induced polyuria mechanisms.