Cardio-respiratory synchronization and myocardial function in hypoxic carp, Cyprinus carpio L.



Moderate hypoxia (Pio2, = 50 mmHg) caused tachycardia in carp, Cyprinus curpio Linnaeus, whereas severe hypoxia (Pio2, from 30 to 5 mmHg) coincided with bradycardia accompanied by alterations of the waveforms of the electrocardiogram. A cardio respiratory synchronization developed during hypoxia and was maintained during bradycardia. The data raised the question: Does hypoxic bradycardia in part result from myocardial dysfunction or only from regulatory adjustments?