Histidine-trytophan-ketoglutarate cardioplegia reduces inflammatory response and serum levels of myocardial enzymes in newly developed right-thoracotomy rat model

The objective of this research was to establish a rat model for cardiopulmonary bypass (CPB) with cardiac arrest and resuscitation that is both practical and economical and simulates clinical cardiac surgery. Concurrently, the study aimed to evaluate the myocardial protective effects conferred by histidine-tryptophan-ketoglutarate (HTK) cardioplegia. Thirty rats were randomly assigned to three groups: the histidine-tryptophan-ketoglutarate (HTK), 4:1 blood cardioplegia (BC) and del Nido cardioplegia (DN) groups. The cardiopulmonary bypass (CPB) procedure was implemented and sustained for a duration of one hour. Subsequent to the cessation of CPB, the rats were subjected to monitoring and observation for an additional two hours. Following this observation period, the heart and blood samples were procured for subsequent analysis. During CPB, the average hematocrit level was significantly below the typical physiological range (P < 0.001). Histopathological scores were notably lower in the HTK group in contrast to the BC group (P < 0.001) or the DN group (P < 0.001). At 2 h after weaning off CPB, the levels of CK and CKMB in the DN and BC groups were notably elevated compared to the HTK group (P < 0.001). The levels of IL-6 and TNF-α proteins were notably increased in all three groups (P < 0.001), with the BC and DN groups showing higher increases compared to the HTK group (P < 0.001). This compact animal model of cardiopulmonary bypass (CPB) with cardiac arrest and resuscitation might allow for both the study of myocardial ischemia-reperfusion injury as well as cardioprotective strategies. HTK cardioplegia could reduce inflammatory response and serum levels of myocardial enzymes in this newly developed right thoracotomy rat model.