Fig. 8. Glibenclamide blocks amaranth transport. Eight tubules were arranged radially for classical (Ramsay) secretion assays (Dow et al., 1994): the bathing drops are just out of shot. Droplets were collected every 10 min, and so the colour of the droplets provides a correlate of real-time amaranth transport. (A) Secreted drops before glibenclamide was added. (B) Secreted droplets 35 min after glibenclamide was added to the final concentrations (in mmol l^-1) shown. Drops labelled `C' had no glibenclamide added to the bubbles. The concentration of amaranth in the reservoir bubbles was 2 µmol l^-1.