Fig. 3. CAP_2b- and Drosokinin-stimulated fluid transport are inhibited in itpr mutants. Fluid transport assays were performed on intact tubules as described in Fig. 1 for the following lines: Oregon R (control), itpr^XR12/+, itpr^90B.0/+, itpr¹⁶⁶⁴/+, itpr¹⁶⁶⁴/itpr^XR12, itpr¹⁶⁶⁴/itpr^90B.0, itpr¹⁶⁶⁴/itpr¹⁶⁶⁴ and itpr^WC361/itpr^UG3. Either (A) 10^-7 moll^-1 CAP_2b or (B) 10^-7 moll^-1 Drosokinin were added at 30 min, and transport rates were measured for a further 30 min. No change in basal secretion rate was observed in itpr mutants. Furthermore, kinetics of the fluid secretion response in all lines were similar (data not shown). To aid comparison between stimulated transport rates, data are expressed as the % stimulation of secretion [(maximal stimulated rates minus the mean of three basal secretion rate readings)/(mean basal rate)x100% ± S.E.M.; N=15-20] upon stimulation with CAP_2b or Drosokinin. Stimulated fluid transport rates that are significantly different from wild type are denoted by ^* (P<0.05, Student's t-test, unpaired samples).