Fig. 8. Secretion rate and secreted fluid Na⁺ and K⁺ concentrations for 4th instar Rhodnius Malpighian tubules set up in a rescue experiment. Values are means ± S.E.M. (N=8 tubules for each group). Filled circles represent tubules rescued with 20 mmol l^-1 glutamine at t=60 min (indicated by the arrow), and open circles represent control tubules. Asterisks represent significant (P<0.05) increases or decreases relative to controls.