ship of architecture and function uf the right ventricle. Am. J. Physiol. 2N3(1): ,)174-179. 1970.-The sequence of contraction and augmentation patterns in contractile force of the sinus and conus regions of the right ventricle were analyzed under control, vagal,

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Employing multiple chamber pressure recording techniques, the presence of fibers within the right and left cervical vagosympathetic trunks which innervate both right and left ventricles has been demonstrated. Electrical excitation of the cervical vagosympathetic in the atropinized dog elicited a distinct increase in both rate of rise and in maximal systolic intraventricular pressures, with or without cardiac acceleration. It persisted during electrical pacing of the right ventricle. In many animals, the a-wave of the atrial pressure traces also showed augmentation, but this was not consistent or essential for the ventricular response. Although pulmonary vasoconstriction was not ruled out as a concurrent event, its contribution to right ventricular augmentation was not essential as demonstrated in bilateral, isovolumetric ventricular preparations. The evidence indicates the presence of adrenergic fibers in the cervical vagosympathetic trunk which are distributed to all four cardiac chambers. Their effects on the heart are abolished by the /3-blocking agent, propranolol, and are unaffected by eserine administration.

Simultaneous measurements of pressure and flow have been made in the vessels of the aortic arch in chloralose-anesthetized dogs under three conditions; control, cardiac sympathetic (SS), and vagal nerve stimulation (VS). The specific sites studied include ascending aorta (AA), descending thoracic aorta (DTA), and brachiocephalic (BCA), left subclavian (LSC), and common carotid arteries (CA). Recorded data were analyzed by Fourier series methods and were used to calculate vascular impedance spectra, pressure and flow propagation characteristics, and hydraulic power. The distribution of cardiac output was found to be 70% to DTA, 22.2% to BCA, and 6.5% to LSC. The fraction of cardiac output to the BCA, LSC, and CA was increased by both SS and VS. The hydraulic power was distributed to the arch vessels nearly the same as the cardiac output. Hydraulic power dissipated in the arch vessels averaged 6% of the total AA hydraulic power and was increased by SS and decreased by VS. The results suggest that viscous losses in the arterial walls represent a considerable portion of the power dissipation. A similarity found in the vascular impedance spectra at the various sites for all three conditions was also observed for the transmission characteristics of pressure and flow harmonics between the sites. The results suggest that major reflections do not occur in the proximal aorta.