Fig. 2

PHH associates with Na⁺/K⁺-ATPase hyperactivity. a Schematic illustration of the principle behind the ⁸⁶Rb⁺ isotope flux assays. ⁸⁶Rb⁺ is a congener for K⁺ and can be used to quantify the transport activity. b Loss of ⁸⁶Rb⁺ from the choroid plexus as a function of time in control rats (n = 4) and PHH rats (n = 4) in presence or absence of 20 µM bumetanide. The y-axis is the natural logarithm of the choroidal ⁸⁶Rb⁺ amount left at time T (A_T) divided by the initial amount at time 0 (A₀). c Efflux rates for ⁸⁶Rb⁺ in control rats (n = 4) and PHH rats (n = 4) in presence of absence of 20 µM bumetanide. d NKCC1-mediated efflux rates (bumetanide-sensitive fractions) for ⁸⁶Rb⁺ in control rats (n = 4) and PHH rats (n = 4). e ⁸⁶Rb⁺ influx (measured in counts per min; cpm) in control rats (n = 6) and PHH rats (n = 5) in presence or absence of 2 mM ouabain. f NKA-mediated ⁸⁶Rb⁺ influx (ouabain-sensitive fractions) in control rats (n = 6) and PHH rats (n = 5). Error bars represent standard deviation and statistical significance was tested with an unpaired two-tailed t-test or a one-way ANOVA followed by Sidak’s multiple comparisons test (c and e). *P < 0.05, ***P < 0.001, NS not significant