Fig. 9.

Na⁺-K⁺-ATPase activity is reduced in HK-2 and HKC11 cells after pharmacological blockade of CK1δ/ε. HK-2 (A) and HKC11 (B) cells both showed significantly reduced Na⁺-K⁺-ATPase activity after treatment with the CK1δ/ε inhibitor. Cells were treated with 10 μM PF670462 for 24 h in serum-free DMEM-F-12 containing 5 mM glucose. Cells were then treated with 5 μM monensin to short circuit Na⁺ channels and thus measure Na⁺-K⁺-ATPase transport at V_max. Half of the cells were treated with 1 uM ouabain for 30 min followed by the addition of ⁸⁶RbCl for 10 min to determine Na⁺-K⁺-ATPase-specific activity. Cells were then lysed, and protein was measured to normalize uptake to total protein. Values are calculated as nmoles of ⁸⁶Rb accumulated per milligram of protein per 10 min and expressed as percent activity relative to vehicle-treated control cells. Values are means ± SE; n = 6 in A and 12 in B. **P < 0.01.