The article reports the discovery and isolation of a new hypotensive peptide, neurotensin, from bovine hypothalami. The peptide was purified through a series of chromatographic and electrophoretic techniques, resulting in a homogeneous tridecapeptide composed of Lys, Arg, Asx, Glx, Pro, Ileu, Leu, Tyr. Neurotensin lacks a free NH2 terminus but has a free COOH terminus that can be acted upon by carboxypeptidase A. It exhibits hypotensive effects in rats, stimulates the contraction of guinea pig ileum and rat uterus, and causes relaxation of the rat duodenum. These pharmacological properties classify it as a "kinin," but its chemical composition distinguishes it from known peptides. The study also explores the biological activities of neurotensin, including its vasodilatory and hypotensive effects, and its ability to increase vascular permeability. The authors speculate on the physiological functions of neurotensin, suggesting it may play a role in neural communication or as a neurohormone in the hypothalamus.The article reports the discovery and isolation of a new hypotensive peptide, neurotensin, from bovine hypothalami. The peptide was purified through a series of chromatographic and electrophoretic techniques, resulting in a homogeneous tridecapeptide composed of Lys, Arg, Asx, Glx, Pro, Ileu, Leu, Tyr. Neurotensin lacks a free NH2 terminus but has a free COOH terminus that can be acted upon by carboxypeptidase A. It exhibits hypotensive effects in rats, stimulates the contraction of guinea pig ileum and rat uterus, and causes relaxation of the rat duodenum. These pharmacological properties classify it as a "kinin," but its chemical composition distinguishes it from known peptides. The study also explores the biological activities of neurotensin, including its vasodilatory and hypotensive effects, and its ability to increase vascular permeability. The authors speculate on the physiological functions of neurotensin, suggesting it may play a role in neural communication or as a neurohormone in the hypothalamus.