Abstract
ECG and blood pressure in bulbus arteriosus of rainbow trout during hypoxia were measured simultaneously under MS-222 anesthesia. Increment of stroke volume, compared to the control, was surmised based on the facts that remarkable bradycardia occurred immediately after the onset of hypoxia and systolic blood pressure (BPs) in bulbus arteriosus and the time required from the BPs-increase to the end of BPd-decrease (BPi) increased. Extended times of one systole of the atrium and ventricle were also indicated by the extended times of Pi, QRSi and QTi measured by ECG. After a prolonged time of hypoxia, arrhythmia and cardiac arrest occurred. Reductions of the systolic power and conduction rate of excitation in the ventricle at the stage of arrhythmia were also indicated by the reduced BPs and BPi and remarkably extended values of Pi, QRSi and QTi, respectively.
