The Effects of Endurance Exercise Training on the Coronary Vascular Responsiveness to Intracoronary Acetylcholine in Swine
Abstract
Acetylcholine, the parasympathetic nervous system neurotransmitter, is a potent vasoconstrictor of the coronary vasculature in swine, as well as the human in states of altered vascular function. The parasympathetic nervous system is believed to have a role in the pathophysiology of coronary vasospasm in patients with Prinzmetal's variant angina. There is also evidence supporting increased parasympathetic neural activity with endurance exercise training. The aim of these studies was to determine if endurance exercise training increases the coronary vascular responsiveness to intracoronary injections and infusions of acetylcholine in swine. Sensitivity to acetylcholine-mediated vasoconstriction was evaluated on the basis of the concentration required to achieve certain reductions in coronary blood flow in trained and sedentary pigs. Training was achieved by 10 weeks of treadmill running, after which all pigs were anesthetized with pentobarbital, and instrumented for an open-chest experiment. Intracoronary acetylcholine bolus injections (0.5 - 4.0 micro g) were administered into the left anterior descending coronary artery at rest, and during simulated exercise, achieved by intravenous norepinephrine infusion, to determine acetylcholine's vasoconstrictive action. Acetylcholine (3.0 micro g) was also injected at one minute after cessation of exercise, and after muscarinic receptor blockade with intracoronary atropine injection (40 micro g). Acetylcholine bolus injections caused similar percent reductions in coronary blood flow in both Exercise Trained and Sedentary groups at rest and during simulated exercise. However, Exercise Trained swine demonstrated a significantly (p<0.05) increased sensitivity to acetylcholine administered after cessation of exercise.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 09, 1993
- Accession Number
- AD1011299
Entities
People
- Brenda A. Tondi
Organizations
- Uniformed Services University of the Health Sciences