NATRIURETIC PEPTIDE IMMUNOREACTIVITY IN NERVE STRUCTURES AND PURKINJE-FIBERS OF HUMAN, PIG AND SHEEP HEARTS

Atrial natriuretic peptide is a well-described peptide in cardiac Purk inje fibres and has been shown to interfere with the autonomic regulat ion in the heart of various species, including man. Recently, we detec ted immunoreactivity for the peptide in intracardial ganglionic cells and nerve fibre varicosities of bovine hearts, by the use of a modifie d immunostaining technique that induced an improved detection of natri uretic peptides. These findings raised the question as to whether natr iuretic peptides are detectable in these tissues in man and other spec ies. The conduction system from human, pig and sheep hearts was dissec ted and processed with antisera against atrial natriuretic peptide and the closely related brain natriuretic peptide. Immunostaining for the brain natriuretic peptide was detected in some Purkinje fibres in all of these species. Interestingly, in pig, sheep and human hearts, some ganglionic cells and nerve fibres showed atrial natriuretic peptide i mmunoreactivity, particularly in the soma of human ganglionic cells. T his is the first study showing immunoreactivity for the atrial natriur etic peptide in nerve structures and for the brain natriuretic peptide in Purkinje fibres of the human heart. The results give a morphologic al correlate for the documented effects of atrial natriuretic peptide on the heart autonomic nervous system and for the presumable effects o f brain natriuretic peptide in the conduction system of man.