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Effect of adrenaline on cardiac force-interval relationship
A J Drake-Holland1, R Sitsapesan, K Herbaczynska-Cedro
1Charing Cross and Westminster Medical School, London, United Kingdom.
Cardiovascular Research
|May 1, 1992
Summary
Adrenaline accelerates mechanical restitution in cardiac muscle, suggesting faster activator reavailability. It also increases the recirculation fraction of contractile activators, indicating a dual inotropic mechanism.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
Background:
- Force-interval relationships are crucial for understanding cardiac contractility.
- Adrenaline's effects on these processes are not fully elucidated.
Purpose of the Study:
- To investigate the impact of adrenaline on cardiac force-interval processes.
- To determine if adrenaline influences mechanical restitution and post-extrasystolic potentiation.
Main Methods:
- Studied isometric force in guinea pig papillary muscles and left ventricular pressure rise (LVdP/dtmax) in dogs.
- Measured contractility indices during variable pacing intervals with premature beats.
Main Results:
- Adrenaline increased force and its rate of rise in isolated papillary muscles.
- Adrenaline variably accelerated mechanical restitution in isolated muscles but not in dogs.
- Adrenaline slowed potentiation decay in isolated preparations, increasing the slope of contractility relationship.
Conclusions:
- Adrenaline speeds mechanical restitution, likely by enhancing contractile activator reavailability.
- Adrenaline increases the recirculation fraction of contractile activators.
- Adrenaline exerts an inotropic effect through at least two distinct mechanisms.