Fig. 4. Graph summarizing the results of rescue experiments for Rhodnius prolixus. All amino acids were tested at 20 mmol l^-1 except threonine, which was tested at 10 mmol l^-1 due to its solubility. Each bar represents the mean secretion rate (+ S.E.M.) as a percentage of the corresponding control mean. N=7-9 tubules for each amino acid and corresponding control group. The broken line indicates the control rate (100%). Asterisks represent significant (P<0.05) increases or decreases in secretion rate relative to the controls. Tyrosine was not tested because its low solubility did not permit preparation of an appropriate stock solution at 10x the final concentration. The insets show dose—response curves for stimulation by glutamine and inhibition by arginine and lysine. Values are means ± S.E.M. (N=17-13 tubules for each amino acid and corresponding control group).

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