The overall objective of the proposed project is to understand the control of the heart by the sympathetic nervous system, with emphasis on the processes involved in the regulation of the liberation and dissipation of the neurotransmitter. The cardiac responses to sympathetic neural activity depend in part on the concentration of norepinephrine (NE) in the neuroeffector gaps, which in turn depends on the rates of NE release and removal. In this grant period, the major emphasis will be to define the roles of some of the physical processes (diffusion and bulk transport) involved in the dissipation of NE. Studies will be carried out in anesthetized, open-chest dogs. We will stimulate the cardiac sympathetic nerves, and will measure the chromotropic and inotropic responses of the heart and the rates of NE overflow into the coronary sinus blood. These observations will be made in the presence and absence of cocaine. Complete heart block will be produced, so that the heart rate can be varied over a wide range by artificial pacing. The effects of diffusion on the dissipation of NE will be determined by varying the rate of coronary blood flow. The effects of bulk transport, ascribable to the massaging action of the beating heart, will be determined by varying separately the frequency and the strength of the cardiac contractions. We will also continue our investigations of the factors that govern the neuronal release of NE, especially the presynaptic effects of adenosine in the heart. We will determine the effects of exogenous and endogenous adenosine on the cardiac responses to sympathetic stimulation and on the associated rates of NE overflow into the coronary sinus blood.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL015758-13
Application #
3335053
Study Section
Cardiovascular Study Section (CVA)
Project Start
1978-05-01
Project End
1986-04-30
Budget Start
1985-05-01
Budget End
1986-04-30
Support Year
13
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Mount Sinai Medical Center
Department
Type
DUNS #
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Henning, R J; Levy, M N (1991) Effects of autonomic nerve stimulation, asynchrony, and load on dP/dtmax and on dP/dtmin. Am J Physiol 260:H1290-8
Warner, M R; Senanayake, P D; Ferrario, C M et al. (1991) Sympathetic stimulation-evoked overflow of norepinephrine and neuropeptide Y from the heart. Circ Res 69:455-65
Levy, M N; Wiseman, M N (1991) Electrophysiologic mechanisms for ventricular arrhythmias in left ventricular dysfunction: electrolytes, catecholamines and drugs. J Clin Pharmacol 31:1053-60
Levy, M N (1990) Autonomic interactions in cardiac control. Ann N Y Acad Sci 601:209-21
Furukawa, Y; Wallick, D W; Martin, P J et al. (1990) Chronotropic and dromotropic responses to stimulation of intracardiac sympathetic nerves to sinoatrial or atrioventricular nodal region in anesthetized dogs. Circ Res 66:1391-9
Henning, R J; Khalil, I R; Levy, M N (1990) Vagal stimulation attenuates sympathetic enhancement of left ventricular function. Am J Physiol 258:H1470-5
Cheng, J; Levy, M N (1990) Feedback mechanisms and dynamics of atrioventricular node propagation. Ann N Y Acad Sci 591:1-10
Warner, M R; Levy, M N (1990) Sinus and atrioventricular nodal distribution of sympathetic fibers that contain neuropeptide Y. Circ Res 67:713-21
Furukawa, Y; Martin, P; Levy, M N (1990) AV junctional rhythm induced by sympathetic-parasympathetic imbalance in dog hearts. Am J Physiol 259:H839-42
Levy, M N (1989) Role of calcium in arrhythmogenesis. Circulation 80:IV23-30

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