Key result
Respiratory acidosis and alkalosis altered sympathetic and parasympathetic influence on heart rate and A-V conduction time, but did not change the shape and duration of atrial and ventricular MAPs.
Why the study?
Does respiratory acidosis and alkalosis affect myocardial excitation in anesthetized dogs?
Does respiratory acidosis and alkalosis affect myocardial excitation in anesthetized dogs?
Respiratory acidosis and alkalosis alter autonomic tone, heart rate, and A-V conduction in dogs, but do not directly change the shape or duration of ventricular monophasic action potentials.
Respiratory pH shifts modulate canine HR and AV conduction via autonomic tone without altering MAPs; leaves open direct myocardial effects in humans.
In anesthetized dogs electrocardiogram and monophasic action potentials (MAPs) were recorded from the right atrium and the right ventricle by intracardiac suction electrode technique. The animals were subjected, by means of ventilation with CO2 and hyperventilation, to periods of respiratory acidosis and respiratory alkalosis, respectively. Pronounced respiratory acidosis induced an increased sympathetic activity followed by a decrease in heart rate and prolongation of the A-V conduction time whereas the shape and duration of the atrial and ventricular MAPs remained unaltered. Arterial hypoxia in combination with pronounced respiratory acidosis did not influence the MAP durations. Respiratory alkalosis resulted in an increased sympathetic influence on the heart activity whereas the shape and duration of the atrial and the ventricular MAPs remained unaffected. During pronounced hyperventilation with increasing central venous pressure an increased parasympathetic influence on the heart activity with decrease in the heart rate, prolongation of the A-V conduction time and shortening of the atrial MAP duration was recorded.
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Samuelsson et al. (1976) studied this question. Respiratory acidosis and respiratory alkalosis was evaluated on Electrocardiogram and monophasic action potentials (MAPs) from the right atrium and right ventricle. Respiratory acidosis and alkalosis altered sympathetic and parasympathetic influence on heart rate and A-V conduction time, but did not change the shape and duration of atrial and ventricular MAPs.
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