Altered Dynamics in Splanchnic Amino Acid Extraction During Early Sepsis Recovery in Pigs: Whole Body Compared with Interorgan Balance Assessments.

BACKGROUND

Establishing the metabolic fate of nutrients from food intake is crucial for interpreting the benefits of food interventions. Using stable isotopes labeled amino acids (AA) such as L-phenylalanine (Phe) during feeding allows for the determination of first-pass splanchnic extraction (SPE) on a whole-body level (WbSPE). The relationship between this measure and the total fraction of food-derived Phe retained by the splanchnic area has not been validated.

OBJECTIVE

Therefore, we compared WbSPE with the enteral-derived Phe and actual PheSPE, measured by splanchnic-trans-organ fluxes in both healthy and early sepsis recovery states.

METHODS

In 25 catheterized healthy control or Pseudomonas-induced-septic pigs (±25 kg), primed-continuous intravenous infusions of L-[ring-D5]-Phe and continuous enteral infusion of an AA mixture (per kg/h: 0.031 g N, 0.78 g maltodextrin), containing L-[1-13C]-Phe, were administered for 6 h. We collected arterial, portal, and hepatic venous blood and measured plasma enrichments and tracee concentrations by liquid chromatography-mass spectrometry (LC-MS/MS). Statistical analysis was performed using GraphPad Prism. Best-fit group means from the last 3 h were compared using an unpaired t-test. The data are presented as mean [95% confidence interval].

RESULTS

In the healthy control group, WbSPE was 38[16,61]% (P<0.0001) of the enteral-derived Phe SPE and tended to be 16[-1,34]% (P=0.0761) higher than the actual Phe tracee SPE. However, WbSPE was the same as first-pass SPE. In the septic group, WbSPE was increased 29[8,50]%, (P=0.001) whereas the actual Phe tracee SPE remained unchanged, whereas portal-drained viscera fluxes showed a diminished release of enteral-derived tracee Phe (P < 0.0001).

CONCLUSIONS

WbSPE reflects first-pass SPE rather than enteral-derived tracee SPE or the actual SPE. Our observations suggest that whole-body level calculated SPE may be challenged in estimating food-derived amino acid SPE in response to steady meal intake. During early sepsis recovery, less AA are absorbed, and this changes the dynamics between first-pass and the actual SPE.