Phenylalanine isotope pulse method to measure effect of sepsis on protein breakdown and membrane transport in the pig

The primed-continuous (PC) phenylalanine (Phe) stable isotope infusion methodology is often used as a proxy for measuring whole body protein breakdown (WbPB) in sepsis. It is unclear if WbPB data obtained by an easy-to-use single IV Phe isotope pulse administration (PULSE) are comparable to those by PC. Compartmental modeling with PULSE could provide us more insight in WbPB in sepsis. Therefore, in the present study, we compared PULSE with PC as proxy for WbPB in an instrumented pig model with Pseudomonas aeruginosa-induced severe sepsis (Healthy: n = 9; Sepsis: n = 13). Seventeen hours after sepsis induction, we compared the Wb rate of appearance (WbRa) of Phe obtained by PC (L-[ring-13C6]Phe) and PULSE (L-[15N]Phe) in arterial plasma using LC-MS/MS and (non)compartmental modeling. PULSE-WbRa was highly correlated with PC-WbRa (r = 0.732, P < 0.0001) and WbPB (r = 0.897, P < 0.0001) independent of the septic state. PULSE-WbRa was 1.6 times higher than PC-WbRa (P < 0.001). Compartmental and noncompartmental PULSE modeling provide comparable WbRa values, although compartmental modeling was more sensitive. WbPB was elevated in sepsis (Healthy: 3,378 ± 103; Sepsis: 4,333 ± 160 nmol·kg BW–1·min–1, P = 0.0002). With PULSE, sepsis was characterized by an increase of the metabolic shunting (Healthy: 3,021 ± 347; Sepsis: 4,233 ± 344 nmol·kg BW–1·min–1, P = 0.026). Membrane transport capacity was ...

Source: AJP: Endocrinology and Metabolism - June 4, 2017 Category: Endocrinology Authors: Ten Have, G. A. M., Engelen, M. P. K. J., Wolfe, R. R., Deutz, N. E. P. Tags: Research Article Source Type: research