EFFECT OF PARACETAMOL AND CELECOXIB ON RENAL FUNCTION, SODIUM AND POTASSIUM METABOLISM, AND EXTRACELLULAR FLUID VOLUME IN RATS UNDER ACUTE HEAT INJURY

Introduction. Acute heat injury is a life-threatening condition caused by excessive environmental heat exposure. It leads to impairedthermoregulation, dehydration, electrolyte imbalance, renal dysfunction, and systemic inflammation. The limited efficacy of existingpharmacological treatments highlights the need to explore new thermoprotective agents. In a rat model, celecoxib and paracetamol have shown thermoprotective properties, outperforming several NSAIDs. However, their impact on renal function and water-electrolyte balance under heat stress remains unclear. Previous studies have shown that celecoxib and paracetamol have prevented hyperthermia, but only celecoxib improves CNS function during the recovery period.The aim of the study is to evaluate the effect of paracetamol and celecoxib on renal function, extracellular fluid volume, and hematocritunder acute heat injury.Materials and methods. The study was conducted on 57 adult white male rats exposed to + 55°C for 30 minutes. Paracetamol (125 mg/kg) and celecoxib (8.4 mg/kg) were administered orally before exposure. Renal function, sodium and potassium metabolism, extracellularfluid volume, and hematocrit were assessed by standard methods.Results. Heat injury led to hyperthermia, oliguria, reduced glomerular filtration rate, hyponatremia, hyperkalemia, and hemoconcentration.Both drugs reduced hyperthermia. However, paracetamol caused acute renal failure, azotemia, and worsened electrolyte imbalance. Celecoxibcorrected ion disturbances, normalized the sodium/potassium ratio, showed no nephrotoxicity, and reduced hemoconcentration. The findingsjustify the use of celecoxib as a potential thermoprotective agent.