Related Experiment Videos
Intrapericardial blocking agents have extracardiac effects in dogs
S W Mittelstadt1, K P O'Hagan, L B Bell
1Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226.
The American Journal of Physiology
|June 1, 1994
Summary
Intrapericardial administration of hexamethonium, propranolol, and atropine impacts extracardiac receptors in dogs. These drugs, when infused into the pericardial sac, demonstrated significant effects on nerve activity and smooth muscle responses.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Pharmacology
Background:
- The pericardial sac's role in housing extracardiac receptors is not fully understood.
- Investigating the localized effects of drugs within the pericardial space is crucial for understanding autonomic regulation.
Purpose of the Study:
- To investigate the extracardiac effects of intrapericardial hexamethonium, propranolol, and atropine in anesthetized dogs.
- To determine if these drugs modulate autonomic nerve activity and smooth muscle function via receptors within the pericardial sac.
Main Methods:
- Anesthetized dogs were subjected to intrapericardial infusions of hexamethonium, propranolol, and atropine.
- Renal sympathetic nerve activity (RSNA) was monitored.
- Tracheal smooth muscle tone was assessed by measuring endotracheal cuff pressure changes during vagal and ansa stimulation.
Main Results:
- Intrapericardial hexamethonium dose-dependently decreased RSNA.
- Intrapericardial atropine attenuated vagally mediated increases in tracheal smooth muscle tone.
- Intrapericardial propranolol blocked beta-adrenergic receptor-mediated relaxation of tracheal smooth muscle.
Conclusions:
- Hexamethonium, atropine, and propranolol administered intrapericardially exert significant extracardiac effects.
- These findings suggest the presence and functional relevance of extracardiac receptors within the pericardial space.
- Localized drug delivery to the pericardium can modulate autonomic responses.