COMPARATIVE EVALUATION OF EXPERIMENTAL INJURY MODELS FOR ASSESSING SYSTEMIC LACTATE RESPONSE

Abstract

Experimental models of tissue injury may differ in their ability to obtain a measurable systemic metabolic response. The aim of our study was to compare systemic lactate dynamics across three trauma models-muscular, vascular, and bone trauma-and to assess their suitability for investigating circulating lactate as a marker of metabolic response. Materials and methods:  Male Wistar rats were allocated to three groups:  skeletal muscle ischemia-reperfusion, vascular trauma, and tibial bone injury (n = 11/group). Blood lactate was measured at three time points (T1-T3). Lactate peak, final concentration, clearance, and temporal slope were calculated and compared between models. Non-parametric statistical methods were applied because of deviations from normality. Results:  The three models generated distinct lactate trajectories. In the muscular trauma group, lactate changed from 2.19 ± 0.67 mmol/L at T1 to 1.44 ± 0.84 mmol/L at T2 and increased to 3.33 ± 1.15 mmol/L at T3 (Friedman χ² = 14.73, p < 0.001). This model showed negative lactate clearance (−59.0 ± 40.3%) and a positive temporal slope (+0.57 ± 0.46). Conversely, vascular and bone trauma resulted in lower final lactate concentrations (0.98 ± 0.56 and 1.14 ± 0.18 mmol/L), positive clearance (+22.8 ± 27.0% and +27.6 ± 12.5%), and negative temporal slopes. Conclusions:  Systemic lactate kinetics depend on injury type. Muscular trauma produced the most pronounced and sustained response, characterized by late lactate elevation and negative clearance, whereas vascular and bone trauma showed progressive lactate reduction. These findings support careful model selection when circulating lactate is used to investigate systemic metabolic responses to tissue injury.