(HCl . N-G - NO2 - Arg)(2) Lys - OCH3, (HCl . N-G - NO2 - Arg)(2)Lys-OH, [(HCl . N-G - NO2 - Arg)(2)Lys](2)Lys - OCH3, and [(HCl . N-G - NO2-Arg)(2)Lys](2) Lys-OH were synthesized by use of a solution method. Their effect on septic shock was studied in vivo. The results indicate that increasing the number of N-G-NO2-Arg residues in a molecule may be useful to improve the response to septic shock.