Nervous system mediated cardiac arrest in mangrove killifish

Abstract Generating and regulating the heartbeat in response to both internal physiological cues and the external environment is mediated by conserved autonomic neural pathways. Heart rate regulation is fundamental to survival, and while it is dynamic, complete cessation is often associated with pathology or extreme physiological stress. However, we have found an abrupt and complete heart-stopping behavior that occurs frequently, causes no harm, and is followed by full recovery. Here we show that embryos of the mangrove killifish, Kryptolebias marmoratus , exhibit heart-stopping in response to physical disturbance (HSPD). Tactile or vibrational stimulation triggers embryos to stop their hearts, sometimes for over a minute, before restarting and beating normally. This behavior begins in the later stages of embryonic development prior to hatching and is retained throughout diapause. We show that HSPD is a developmentally regulated, neuronally mediated and plastic response, shaped by sensory input. These findings identify a previously undescribed form of cardiac regulation involving neural and intrinsic cardiac system interactions. This work provides new insight into how sensory stimulation influences vertebrate cardiac activity and contributes to establishing K. marmoratus as a model for studying conserved neurocardiac mechanisms relevant to cardiac rhythm regulation and dysfunction.