Release of atrial natriuretic peptide-like immunoreactive material during stretching of the rat atrium in vitro.

In 1979 De Bold showed that the numbers of atrial specific granules varied with changes in water and electrolyte balance of the whole animal. Two years later, he showed that atrial extracts had a natriuretic effect. The active principle has now been identified as a polypeptide formed by cleavage of a larger precursor molecule. The rate of release of atrial natriuretic peptide-like immunoreactive material by the isolated, perfused rat heart has been shown to be increased when the right atrial pressure is raised. The mechanism of release remains, however, unknown. We describe, here, experiments which show a transient release of atrial natriuretic peptide-like immunoreactive material from isolated rat atria subjected to a constant load in an organ bath. The release appears to be specific in that it is not accompanied by a parallel release of other peptides contained in nerve fibres or of creatine kinase contained in myocytes.