Peripheral innervation of the heart

Summary

The present immunohistochemical study demonstrates the multiplicity, histotopography and origin of peptidergic innervation in the mammalian heart. Neuropeptide Y (NPY) is the major representative of peptides in cardiac sympathetic efferents. Sympathetic afferents are characterized by the presence of tachykinins, calcitonin gene-related peptide and apparently also some opioid peptides. Predominant peptides of the vagal system are tachykinins. The intrinsic peptidergic system predominantly consists of vasoactive intestinal polypeptide/peptide histidine isoleucine. Paracrine systems are merely opioid-ergic. Target relations of extrinsic and intrinsic peptidergic nerves were found to be more differentiated than currently believed. The different peptidergic neuronal pathways were not strictly separated. The chemical phenotype of the different neuronal pathways and paracrine systems seems to be more complex than presently known. The detailed chemoanatomical data presented here should be a good basis for further clarifying the suggested physiological and pathophysiological roles of multiple cardiac peptide- and non-peptide messenger systems.