Cardiac Muscle, Dr. D. Penney




Factors Affecting Conduction Through the AV Junction:

Speeds -

Catecholamines *
Atropine - blocks Acetylcholine
Quinidine - inhibits vagal effects

Slows
Acetylcholine * *
Digitalis - central vagal (parasympathetic) stimulation
Inhibitors of acetylcholine esterase, Ca++ antagonists (e.g. verapamil)
An increased number of impulses arriving at AV junction increases refractoriness



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