Like many medications, general anesthetics are not without side effects. Researchers at Dalhousie University in Canada were interested in studying the effects of inhaled anesthetics on the heart. Slowed heart rate (bradycardia) is a major adverse side effect of inhaled anesthetics that can lead to death for those undergoing procedures. Because bradycardia occurs in all species of vertebrates that have been studied thus far, the researchers decided to examine how the anesthetics affected zebrafish. Cardiac physiology of zebrafish is quite similar to humans as they also have pacemaker cells and their nervous system helps regulate the heart. Their findings, which were published recently in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, showed that certain inhaled anesthetics can act directly on pacemaker cells of the heart whereas others targeted nervous system innervation of the heart to cause bradycardia. By improving the understanding of how these anesthetics work, researchers hope to inform the development of anesthetics with fewer cardiac side effects.
Stoyek MR, Schmidt MK, Wilfart FM, Croll RP, Smith FM. The in vitro zebrafish heart as a model to investigate the chronotropic effects of vapor anesthetics. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 313(6): R669-679, 2017.