Fig. 12. Glibenclamide mimics the effect of K⁺-free saline. Tubules were dissected in AARS saline (a defined control saline; Linton and O'Donnell, 1999), then either mounted for fluid secretion directly in 10 µl drops of AARS saline or rinsed and mounted for secretion in drops of K⁺-free saline (Linton and O'Donnell, 1999). Readings were taken every 10 min. At 30 min (arrow), glibenclamide was added (to a final concentration of 0.1 mmol l^-1) to half of the AARS and half of the K⁺-free drops. Key: open squares, control saline without glibenclamide; filled squares, control saline with glibenclamide; open circles, K⁺-free saline without glibenclamide; filled circles, K⁺-free saline with glibenclamide. Data are shown as means ± S.E.M. (N=8).