Distribution of vagal afferent fibers of the guinea pig heart labeled by anterograde transport of conjugated horseradish peroxidase.
To determine the distribution of vagal afferent fibers in the heart, wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) or choleragenoid conjugated horseradish peroxidase (B-HRP) was injected into nodose ganglia of guinea pigs. Anterogradely labeled fibers and beaded, terminal-like arborizations were observed in the ascending aorta and aortic arch, the pulmonary trunk and arteries, posterior atrial walls, atrioventricular valves, and ventricles. Control experiments with injection of B-HRP into the cervical vagus nerve indicated that labeled fibers observed in the heart originated from sensory neurons in the nodose ganglia. Neither the density nor distribution of labeling differed between WGA-HRP and B-HRP. Injection of tracer into the left or right nodose ganglion shows that these regions of the heart are bilaterally innervated, although labeling in the left or right posterior atrium was denser after injection into the ipsilateral ganglion. Comparison with a previous study on the distribution of sympathetic afferent fibers in the guinea pig heart suggests that the two afferent systems maintain a complementary, but not mutually exclusive, distribution within the ventricles. Whereas afferents with their source in the spinal ganglia are mainly distributed with coronary arteries on the anterior-superior surface of the ventricles, afferent fibers with their source in the nodose ganglia are concentrated within peri-arterial regions of the posterior-inferior ventricular epicardium and the posterior septal ventricular endocardium. These differences in distributions of afferent systems could play a role in post-infarction autonomic dysfunction and in the symptoms that accompany angina pectoris.
Quigg
M
M
Department of Anatomy, Karolinska Institutet, Stockholm, Sweden.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002772:Cholera Toxin; D005260:Female; D006168:Guinea Pigs; D006329:Heart Conduction System / Q000502:physiology*; D006735:Horseradish Peroxidase; D007267:Injections; D008297:Male; D009333:Neck; D009412:Nerve Fibers / Q000502:physiology*; D009620:Nodose Ganglion; D014630:Vagus Nerve / Q000502:physiology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; C052635:cholera toxin, B subunit-horseradish peroxidase; D002772:Cholera Toxin; D006735:Horseradish Peroxidase