Parasympathetic control of the heart. I. An interventriculo-septal ganglion is the major source of the vagal intracardiac innervation of the ventricles

• Published in: Journal of applied physiology (1985) 2004-06, Vol.96 (6), p.2265-2272
• Main Authors: Johnson, Tannis A, Gray, Alrich L, Lauenstein, Jean-Marie, Newton, Stephen S, Massari, V. John
• Format: Article
• Language: English
• Subjects: Anatomy & physiology; Animals; Axonal Transport; Biological and medical sciences; Cats; Fundamental and applied biological sciences. Psychology; Ganglia, Parasympathetic - physiology; Heart; Heart - anatomy & histology; Heart - innervation; Heart Atria - anatomy & histology; Heart Atria - innervation; Heart Conduction System - physiology; Heart Ventricles - anatomy & histology; Heart Ventricles - innervation; Models, Animal; Nervous system; Vagus Nerve - physiology; Vertebrates: cardiovascular system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00620.2003

1 Department of Pharmacology and 2 Specialized Neuroscience Research Program, Howard University College of Medicine, Washington, District of Columbia 20059 Submitted 16 June 2003 ; accepted in final form 25 September 2003 The locations, projections, and functions of the intracardiac ganglia are incompletely understood. Immunocytochemical labeling with the general neuronal marker protein gene product 9.5 (PGP 9.5) was used to determine the distribution of intracardiac neurons throughout the cat atria and ventricles. Fluorescence microscopy was used to determine the number of neurons within these ganglia. There are eight regions of the cat heart that contain intracardiac ganglia. The numbers of neurons found within these intracardiac ganglia vary dramatically. The total number of neurons found in the heart (6,274 ± 1,061) is almost evenly divided between the atria and the ventricles. The largest ganglion is found in the interventricular septum (IVS). Retrogradely labeled fluorescent tracer studies indicated that the vagal intracardiac innervation of the anterior surface of the right ventricle originates predominantly in the IVS ganglion. A cranioventricular (CV) ganglion was retrogradely labeled from the anterior surface of the left ventricle but not from the anterior surface of the right ventricle. These new neuroanatomic data support the prior physiological hypothesis that the CV ganglion in the cat exerts a negative inotropic effect on the left ventricle. A total of three separate intracardiac ganglia innervate the left ventricle, i.e., the CV, IVS, and a second left ventricular (LV2) ganglion. However, the IVS ganglion provides the major source of innervation to both the left and right ventricles. This dual innervation pattern may help to coordinate or segregate vagal effects on left and right ventricular performance. autonomic control; cardioinhibitory; intracardiac ganglia; parasympathetic nervous system; vagus nerve Address for reprint requests and other correspondence: V. J. Massari, Dept. of Pharmacology, Howard Univ. College of Medicine, 520 W St., N.W., Washington, DC 20059 (E-mail: vmassari{at}howard.edu ).