Hemodynamic Parameters In An Insect Model Of Ethanol Inhalation

Introduction: Insects have been considered useful models to study human diseases and establish drug toxicity due to conservation in insects and mammals of signaling pathways, energetic metabolism and other functional aspects. The use of inhalatory ethanol (EtOH) in humans has recently increased due to its availability on a commercial product AWOL (alcohol without liquid). This way of consumption has been shown to produce deleterious effects on the heart, similar to those produced by EtOH ingestion, in different species. Objective: The aim of the present work was to study the effect of acute EtOH inhalation on the heart performance of the beetle Tenebrio molitor (Linnaeus, 1758). Methods: Adult beetles (10-15 day-old, both sexes) were kept in colonies under a 12:12h illumination cycle and fed wheat bran, carrots, and potatoes. Animals were maintained in a chamber inhaling 70% ethanol (EtOH) or water vapor (CTR) for 1 hour. After decapitation and removal of the elytrum and legs under anesthesia, an incision through the abdomen was made to expose the insect's dorsal vessel (heart). This preparation was placed on the stage of an inverted microscope equipped with a camera. The heart was perfused with physiological solution (1 ml/min a 24  1 ºC) and electrically paced at 1.5, 1.7 and 2.0 Hz for ~10 min at each rate. Video images were recorded (320 x 240) using a Python software developed especially for this purpose, which allowed to dynamically estimate the revolution volume of the heart from the recorded videos. With the heart volume, it was possible to estimate the end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), cardiac output (CO), and ejection fraction (EF). Results and Conclusions: A two-way analysis of variance revealed that EF was not different between CTR and EtOH groups. In both groups, SV tended to fall as frequency was increased (p< 0.05, N = 5). CO and VDF were reduced with rate in the EtOH group, but not in CTR (p< 0.05). Results indicate that acute EtOH inhalation affected the heart performance by reducing CO mainly at higher frequencies, probably by decreased diastolic cardiac filling.