Nov 1, 1975

Effects of autonomic neurohumors on transmembrane potentials of atrial plateau fibers

The American Journal of Physiology
L D Davis

Abstract

Isolated canine atrial plateau fibers were treated with acetylcholine or norepinephrine to note the effects on the transmembrane potential. Acetylcholine, 1.0 or 2.0 mug/ml, consistently reduced the slope of inherent phase 4 depolarization. Increases in maximum diastolic potential and rising velocity occurred along with a decrease in overshoot. The plateau phase disappeared. Pretreatment with atropine, 1.0 mug/ml, prevented these responses, and alone this drug had no discernible effect. Norepinephrine consistently increased the slope of phase 4 depolarization. Frequently plateau fibers generated action potentials by the normal pacemaker mechanism. "Arrhythmias" characterized by spontaneous excitations were induced in 92% of the norepinephrine experiments. Norepinephrine also enhanced the plateau phase of the action potential and decreased the rising velocity and overshoot. Racemic propranolol, 1.0 mug/ml, blocked all the above effects including arrhythmias. Dextropropranolol, 1.0 mug/ml, did not block effects produced by norepinephrine. Acetylcholine, applied to fibers under treatment with norepinephrine, reduced the slope of norepinephrine-induced phase 4 depolarization and terminated induced arrhythmias.

  • References
  • Citations

References

  • We're still populating references for this paper, please check back later.
  • References
  • Citations

Citations

  • This paper may not have been cited yet.

Mentioned in this Paper

Phenylephrine Hydrochloride
Accessory Atrioventricular Bundle
Resting Potentials
Action Potentials
Atropine
Atropinum, atropine
Norepinephrine, (+, -)-Isomer
Right Atrial Structure
Body Surface Area Formula for Dogs
Norepinephrine

About this Paper

Related Feeds

Arrhythmia

Arrhythmias are abnormalities in heart rhythms, which can be either too fast or too slow. They can result from abnormalities of the initiation of an impulse or impulse conduction or a combination of both. Here is the latest research on arrhythmias.

Cardiac Conduction System

The cardiac conduction system is a specialized tract of myocardial cells responsible for maintaining normal cardiac rhythm. Discover the latest research on the cardiac conduction system here.

Atrial Fibrillation

Atrial fibrillation is a common arrhythmia that is associated with substantial morbidity and mortality, particularly due to stroke and thromboembolism. Here is the latest research.