Functional-morphological studies on in vitro cardionatrin release.

Atrial natriuretic peptides (ANP) are hormones produced by the heart atrial cardiocytes in mammals. The main function of these peptides appears to be that of modulating the actions of the renin-angiotensin-aldosterone system. In the rat ANP are stored within specific atrial granules, mainly as a 126-amino acid peptide (cardionatrin IV) which is processed to a 28-amino acid peptide (cardionatrin I) just prior to or during release from cardiocytes. Development of an isolated perifused rat atria preparation has allowed quantitative and qualitative studies on ANP release. Increasing mechanical load in this preparation gives an increased rate of release of immunoreactive cardionatrin. This finding suggests that there is an intrinsic 'stretch-secretion coupling' in the atria.