The spatial–temporal organization of the activation, repolarization and hemodynamics of the heart ventricle in rainbow trout, Oncorhynchus mykiss, adapted to a temperature of 5–7 °C, were studied from the normal sinus rhythm (21.6 ± 4.9 bpm) to the highest possible heart rhythm (HR) (60 bpm), during which deterioration of the contractile activity of the myocardium occurred. Regardless of the HR, the main pattern of excitation of the heart ventricle was the movement of the depolarization wave from the dorsal areas of the base in the base-apical and ventral directions with the capture of the entire thickness of the walls, with a slight difference in the time of activation of the subendocardium compared to the subepicardium. The increase in HR above the sinus rhythm caused significant shortening of local repolarization durations in all areas and layers (endocardial, intramural and subepicardial) of the heart ventricle. Changes in local durations of repolarization led to an increase in the heterogeneity of repolarization of the ventricular myocardium; as a result, a deterioration of its contractility was observed. In relation to the sinus rhythm, the maximal systolic pressure in the heart ventricle decreased, the diastolic and end-diastolic pressure increased, and the maximum rates of pressure rise and fall decreased. In rainbow trout adapted to a temperature of 5–7 °C at sinus rhythm, the pumping function of the heart was probably within the upper limit of the physiological norm, and a further increase in the heart rate led to a decline in myocardial contractility.

虹鳟鱼心室激活、复极化和血流动力学的时空组织，Oncorhynchus mykiss适应 5–7 °C 的温度，从正常窦性心律 (21.6 ± 4.9 bpm) 到最高可能的心律 (HR) (60 bpm) 进行研究，在此期间心肌收缩活动发生恶化. 无论心率如何，心室的主要兴奋模式是去极化波从基底部的背侧区域向基尖和腹侧方向移动，捕获整个壁厚，略有心内膜下与心外膜下激活时间的差异。高于窦性心律的 HR 增加导致心室所有区域和层（心内膜、壁内和心外膜下）的局部复极持续时间显着缩短。局部复极持续时间的变化导致心室心肌复极异质性增加；结果，观察到其收缩性恶化。相对于窦性心律，心室最大收缩压降低，舒张压和舒张末压升高，最大压力上升和下降率下降。虹鳟适应5-7℃窦性心律时，心脏泵血功能可能在生理常态上限内，心率进一步增加导致心肌收缩力下降。心室最大收缩压降低，舒张压和舒张末压升高，最大压降率降低。虹鳟适应5-7℃窦性心律时，心脏泵血功能可能在生理常态上限内，心率进一步增加导致心肌收缩力下降。心室最大收缩压降低，舒张压和舒张末压升高，最大压降率降低。虹鳟适应5-7℃窦性心律时，心脏泵血功能可能在生理常态上限内，心率进一步增加导致心肌收缩力下降。