 Maurício Rocha e Silva and Wilson Teixeira Beraldo, a new endogenous peptide capable of causing a powerful fall of blood pressure on animal preparations, which they called bradykinin.The substance, a short kinin with nine amino acids only, was detected in the blood plasma of dogs after the addition of venom extracted from the "Bothrops jararaca" snake, brought by Rosenfeld from the Butantan Institute.The discovery was part of a continuing study on circulatory shock and proteolytic enzymes related to the toxicology of snake bites, started by Rocha e Silva as early as 1939.