The invention relates to a cyclic organic compound which comprises 16 amino acids or 17 amino acids and has no carboxylic group on the C-terminal end and/or no amino group on the N-terminal end, wherein, if necessary, one of the amino acids is a non-natural amino acid, and wherein the ring closure is formed between a side chain of an amino acid with the C-terminus of another amino acid, or the ring closure is carried out using a non-natural amino acid. The invention also relates to a method for the production thereof and the use thereof for the regulation of vectorial ion channels, the treatment of diseases that are associated with the pulmonary function and the treatment of oedema.
