First recording of cardiac activity in the Anteos menippe bubble and isoflurane interference during anesthetic induction and recovery

Understanding the physiological regulation of cardiac activity in insects remains a central topic in insect biochemistry and physiology. In Lepidoptera, direct electrophysiological characterization of cardiac function is still limited, particularly under anesthetic conditions commonly used during experimental manipulation. In this study, we evaluated the effects of isoflurane anesthesia on cardiac electrophysiology in adult Anteos menippe butterflies during anesthetic induction and recovery. A total of eighteen newly emerged adults were subjected to two experiments. Experiment 1 - behavior during anesthetic induction and recovery with isoflurane (n = 6). Experiment 2 - the animals were divided into a control group (n = 6) and a group treated with isoflurane (n = 6). The animals were monitored during anesthetic induction and recovery with isoflurane; in this case, electrocardiographic signals (ECG) were obtained using 0.06 mm diameter tungsten steel alloy electrodes, implanted to acquire cardiac recordings lasting 30 min under controlled conditions. Isoflurane induced mild and reversible anesthesia, with induction and recovery times of 48.5 ± 8.9 s and 117.7 ± 16.2 s, respectively, without observable excitatory responses. During anesthesia, the frequency of cardiac action potentials decreased significantly, followed by a gradual recovery accompanied by increases in amplitude and linear signal power. Spectral analysis revealed a dynamic redistribution of energy during anesthetic elimination, consistent with chronotropic modulation of cardiac activity. These findings provide new electrophysiological insights into the cardiac physiology of butterflies and support the use of isoflurane as a reliable anesthetic for experimental studies involving cardiac monitoring in lepidoptera and other insects.