CA, but not OkA, alters NHE3 activity. A: 22Na+ uptake was measured in OKP cells treated with vehicle, F/I, or CA (n = 9). B: 22Na+ uptake was measured in OKP cells treated with vehicle, F/I, or OkA (n = 4). Results are expressed as %control. Data are means + SE. P values were calculated using Student's t-tests. *P < 0.05 compared with control.