Reflex Cardiovascular Effects of Epicardial Stimulation by Acetylstrophanthidin in Dogs
Key result
Application of 25 to 100 µg of acetylstrophanthidin to the left ventricular epicardium in dogs caused reflex hypotension and bradycardia mediated by C-fiber mechanoreceptors.
Population
Anesthetized and unanesthetized dogs
Design
Preclinical
Follow-up
up to 12 minutes
Authors
Discussion
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Implication
Indicates potential reflex mechanism in canine model; leaves open whether this contributes to digitalis effects in patients.
Key Points
- To determine the reflex cardiovascular responses and neural mechanisms elicited by applying acetylstrophanthidin to the left ventricular epicardium in dogs.
- Applied 25 to 100 µg of acetylstrophanthidin directly to the left ventricular epicardium of anesthetized and unanesthetized dogs.
- Evaluated neural pathways by cooling the cervical vagi to 8 to 10°C and administering 0.1% procaine hydrochloride to the epicardium.
- Recorded electrophysiological activity from single and multifiber preparations of the right recurrent cardiac nerve.
- Epicardial acetylstrophanthidin induced hypotension and bradycardia with an average latency of 8 seconds and a duration of up to 12 minutes without signs of discomfort.
- The cardiovascular response was abolished by vagal cooling to 8 to 10°C or local epicardial anesthesia with 0.1% procaine hydrochloride.
- Electrophysiological recordings identified the sensory endings as left ventricular surface mechanoreceptors innervated by C-fiber afferents.
Structured PICO
P
Population
Anesthetized and unanesthetized dogs
I
Intervention
Application of 25 to 100 µg of acetylstrophanthidin to the epicardium of the left ventricle
O
Outcome
Hypotension and bradycardiasurrogate
Epicardial stimulation by acetylstrophanthidin induces reflex hypotension and bradycardia mediated by ventricular C-fiber mechanoreceptors, suggesting a potential mechanism for digitalis-induced sinus bradycardia.
Cite This Study
Sleight et al. (1969) studied Cardiovascular reflex. Acetylstrophanthidin was evaluated on Hypotension and bradycardia. Application of 25 to 100 µg of acetylstrophanthidin to the left ventricular epicardium in dogs caused reflex hypotension and bradycardia mediated by C-fiber mechanoreceptors.