Phenotype-Associated Renal and Systemic Patterns During Short-Term Reduced-Tidal-Volume Mechanical Ventilation in Obese and Endotoxemic Rats: An Exploratory Study

Background: Mechanical ventilation (MV) may be associated with extrapulmonary responses shaped by the host inflammatory-metabolic background. Methods: This exploratory study characterized renal changes during 1 h of reduced-tidal-volume mechanical ventilation in male Wistar rats with diet-induced obesity or lipopolysaccharide (LPS)-induced endotoxemia, together with concurrent respiratory, acid–base, metabolic, and hemodynamic alterations. Arterial blood gas, biochemical, hemodynamic, and urinary variables were assessed at the pre-MV and post-MV time points. Renal protein expression was evaluated only at the post-MV time point. Results: The arterial partial pressure of carbon dioxide (PaCO2) decreased significantly in both groups. In the Obese group, metabolic acid–base abnormalities persisted and were accompanied by increases in serum urea and the urinary protein-to-creatinine ratio. In the LPS group, lactate increased, bicarbonate decreased, and mean arterial pressure and serum creatinine increased. At the post-MV time point, renal interleukin-6 expression was lower in the LPS group than in the Obese group, whereas renal tumor necrosis factor-alpha expression was higher in the LPS group than in the Obese group. Conclusions: These results support interpreting the physiological and renal changes observed in association with the integrated experimental protocol, including mechanical ventilation, in relation to the host’s underlying pathophysiology and inflammatory-metabolic context.