“…Introduction Koroza, Kudrin, Kost & Sagitullin (1969) stated that certain N-substituted amino acids markedly enhanced the contractions of the guinea-pig uterus, when applied in exceedingly low concentrations for periods of 10-15 minutes. The most potent one was stated to be N-benzylvaline (Na salt), which was claimed to intensify contractions at concentrations of the order of 10-19 M, or to cause spasm at 10-13 M. Since a number of common amino acids at much higher concentrations have recently been shown to stimulate the uterus (Bedwani, Ishizawa, Pickles & Suwankrughasn, 1977), and as there are a few simple N-substituted amino acids of pharmacological or physiological interest, it seemed worthwhile to see if the claim by Koroza et al (1969) could be substantiated.…”