Xenopus oocytes expressing AQP9 reveal higher uptake of MPP⁺.

Xenopus oocytes expressing AQP4 or AQP9 and uninjected oocytes were exposed to ¹⁴[C]urea or ³[H]MPP⁺. Data were obtained as counts per minute (CPM)/oocyte and averaged for each construct. The uptake was normalized to that of the AQP4-expressing oocytes prior to averaging across the n = 7 experiments with five to ten oocytes included for each experimental condition. Compared with uninjected oocytes and AQP4 expressing oocytes, oocytes expressing AQP9 accumulate significantly higher amounts of urea as well as MPP⁺. Bars are mean ± SEM; *p<0.05, ***; p<0.001.