Immunohistochemical characterization of the intrinsic cardiac neural plexus in whole-mount XXXX heart preparations.

@entity19 @entity4268 @entity1877 @entity10501 @entity669
BACKGROUND: The intrinsic neural plexus of the @entity19 heart has not been adequately investigated despite the extensive use of this species in experimental cardiology. OBJECTIVE: The purpose of this study was to determine the distribution of cholinergic, adrenergic, and sensory neural components in whole-mount @entity19 heart preparations using double immunohistochemical labeling. METHODS/RESULTS: Intrinsic neurons were concentrated within 19    3 ganglia (n = 20 @entity19 ) of varying size, scattered on the medial side of the inferior caval (caudal) vein on the right atrium and close to the pulmonary veins on the left atrium. Of a total of 1,082    160 neurons, most somata (83%) were @entity1877 acetyltransferase ( @entity4268 ) immunoreactive, whereas 4% were @entity669 hydroxylase (TH) immunoreactive; 14% of ganglionic cells were biphenotypic for @entity4268 and TH. The most intense @entity4268 staining was observed in axonal varicosities. @entity4268 was evident in nerve fibers interconnecting intrinsic ganglia. Both @entity4268 and TH immunoreactivity were abundant within the nerves accessing the heart. However, epicardial TH-immunoreactive nerve fibers were predominant on the dorsal and ventral left atrium, whereas most @entity4268 -positive axons proceeded on the heart base toward the large intrinsic ganglia and on the epicardium of the root of the right cranial vein. @entity10501 -positive and calcitonin gene-related peptide-immunoreactive nerve fibers were abundant on the epicardium and within ganglia adjacent to the heart hilum. Small intensely fluorescent cells were grouped into clusters of 3 to 8 and were dispersed within large ganglia or separately on the atrial and ventricular walls. CONCLUSION: Although some nerves and neuronal bundles of the @entity19 epicardial plexus are mixed, most express either adrenergic or cholinergic markers. Therefore, selective stimulation and/or ablation of the functionally distinct intrinsic neural pathways should allow the study of specific effects on cardiac function.
