Frequency-force relationship in the isolated, blood-perfused canine atrium: modification by ACh or ouabain
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چکیده
منابع مشابه
Ouabain-induced negative frequency-force relationship in the isolated, blood-perfused dog atrium.
Effects of ouabain, CaCl2 and verapamil on the frequency-force relationship (FFR) were investigated in the isolated, blood-perfused dog atrial muscle preparation. When ouabain (3 and 10 micrograms) or CaCl2 (0.5, 1 and 2 mg/min) was given into the sinus node artery, the contractile force of the atrial muscle, driven at a constant pacing rate of 2 Hz, increased dose-dependently. Verapamil (1 and...
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In the isolated, blood-perfused, canine right atrium, stimulation of the intramural autonomic nerves evoked negative chronotropic and inotropic responses. The responses were not maintained at a constant level during tonic neural stimulation, but they tended to drift back toward their control levels. These time-dependent changes in the cardiac responses were more pronounced the higher the freque...
متن کاملSuppression of strychnine on the chronotropic and inotropic effects in the isolated, blood-perfused canine atrium.
In the isolated, blood-perfused dog atrium, strychnine evoked dose-dependent decreases in atrial rate and contractile force, and the negative cardiac effects were not influenced by atropine. Strychnine suppressed dose-dependently the negative chronotropic and inotropic responses to intramural parasympathetic nerve stimulation, but not the response to acetylcholine. These results suggest that st...
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Atrial fibrillation occurs spontaneously after bradycardia induced by acetylcholine infusion or vagal stimulation. To determine the mechanism of initiation of this tachyarrhythmia, we infused acetylcholine (5 ml, 10(-3.5) M) into Krebs-Henseleit-perfused isolated canine right atria (n = 10). Unipolar electrograms were recorded from 250 sites simultaneously during control rhythms, pacing (cycle ...
متن کاملCharacterization of the frequency-force relationship in the dog atrium in situ.
Isometric developed tension and rate of development of tension in the in situ atrium of the anesthetized dog have been shown to increase consistently with increasing heart rate over a wide range. This study thus definitely demonstrates that both the ascending and descending staircase effects occur in the dog atrium in situ. At high cardiac rates the velocity of force development may increase wi...
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ژورنال
عنوان ژورنال: Japanese Journal of Pharmacology
سال: 1975
ISSN: 0021-5198
DOI: 10.1016/s0021-5198(19)65496-x