Bazmi Maedeh, Escobar Ariel L
Quantitative Systems Biology Program, School of Natural Sciences, University of California, Merced, Merced, CA, United States.
Department of Bioengineering, School of Engineering, University of California, Merced, Merced, CA, United States.
Front Physiol. 2022 Feb 9;13:793305. doi: 10.3389/fphys.2022.793305. eCollection 2022.
Autonomic regulation plays a central role in cardiac contractility and excitability in numerous vertebrate species. However, the role of autonomic regulation is less understood in fish physiology. Here, we used Goldfish as a model to explore the role of autonomic regulation. A transmural electrocardiogram recording showed perfusion of the Goldfish heart with isoproterenol increased the spontaneous heart rate, while perfusion with carbamylcholine decreased the spontaneous heart rate. Cardiac action potentials obtained sharp microelectrodes exhibited the same modifications of the spontaneous heart rate in response to isoproterenol and carbamylcholine. Interestingly, the duration of the cardiac action potentials lengthened in the presence of both isoproterenol and carbamylcholine. To evaluate cardiac contractility, the Goldfish heart was perfused with the Ca indicator Rhod-2 and ventricular epicardial Ca transients were measured using Pulsed Local Field Fluorescence Microscopy. Following isoproterenol perfusion, the amplitude of the Ca transient significantly increased, the half duration of the Ca transient shortened, and there was an observable increase in the velocity of the rise time and fall time of the Ca transient, all of which are compatible with the shortening of the action potential induced by isoproterenol perfusion. On the other hand, carbamylcholine perfusion significantly reduced the amplitude of the Ca transient and increased the half duration of the Ca transient. These results are interesting because the effect of carbamylcholine is opposite to what happens in classically used models, such as mouse hearts, and the autonomic regulation of the Goldfish heart is strikingly similar to what has been observed in larger mammalian models resembling humans.
自主调节在许多脊椎动物物种的心脏收缩性和兴奋性中起着核心作用。然而，自主调节在鱼类生理学中的作用尚鲜为人知。在此，我们以金鱼为模型来探究自主调节的作用。经胸壁心电图记录显示，用异丙肾上腺素灌注金鱼心脏可增加自发心率，而用卡巴胆碱灌注则降低自发心率。用尖锐微电极记录的心脏动作电位显示，对异丙肾上腺素和卡巴胆碱的反应中，自发心率有相同的变化。有趣的是，在同时存在异丙肾上腺素和卡巴胆碱的情况下，心脏动作电位的持续时间延长。为评估心脏收缩性，用钙指示剂Rhod-2灌注金鱼心脏，并使用脉冲局部场荧光显微镜测量心室心外膜钙瞬变。灌注异丙肾上腺素后，钙瞬变的幅度显著增加，钙瞬变的半持续时间缩短，并且在钙瞬变的上升时间和下降时间的速度上有明显增加，所有这些都与异丙肾上腺素灌注引起的动作电位缩短相一致。另一方面，卡巴胆碱灌注显著降低了钙瞬变的幅度并增加了钙瞬变的半持续时间。这些结果很有趣，因为卡巴胆碱的作用与在经典使用的模型（如小鼠心脏）中发生的情况相反，并且金鱼心脏的自主调节与在类似于人类的大型哺乳动物模型中观察到的情况惊人地相似。
