The isomeric composition of lactated Ringer’s has no differential effect on gastric dysfunction after mesenteric ischemia/reperfusion

Abstract

Lactated Ringer’s is the standard of care trauma resuscitation, but the D-isomer of lactate has been shown to activate proinflammation. We have shown that superior mesenteric artery occlusion (SMAO) without resuscitation causes gastric dysfunction characterized by luminal fluid accumulation and alkalization. In the same model, LR resuscitation protected the ileum, but the presence of the D-isomer abrogated this effect. We, therefore, hypothesized that the isomeric composition of LR resuscitation would have a differential effect on gastric dysfunction and inflammation in this model. Rats underwent sham or SMAO for 60 min. Five minutes prior to clamp removal, SMAO animals received no resuscitation, 20 ml/kg IV (our standard) of either LL or LD isomer LR, or 17 ml/kg IV normal saline (NS) as equal salt load control. Animals were sacrificed at 6 h of reperfusion and gastric mucosa was harvested for analysis. Gastric dysfunction was quantitated by gastric volume and luminal pH. Heme-Oxygenase-1 (HO-1; index of anti-inflammation) and inducible Nitric Oxide Synthase (iNOS; index of proinflammation) protein expression were analyzed by Western immunoblot. Data are reported as mean ± SEM ( n > 6/group; ANOVA). Means with different letters are significantly different. SMAO (no resuscitation) increased gastric volume and pH. All three resuscitative regimens decreased gastric volume, had no effect on pH, and equally induced HO-1 and iNOS. In conclusion, isomeric composition of LR had no differential effect on gastric dysfunction and inflammation after SMAO in contradistinction to its previously observed effects in the ileum. The isomeric immunomodulatory effects of LR appear to be organ specific. TABLE—ABSTRACT P87 Model Volume (ml) pH (pH) HO-1 (AU) iNOS (AU) Sham 0.30 ± 0.05 a 1.67 ± 0.16 a 0.36 ± 0.02 a 0.28 ± 0.03 a SMAO 2.22 ± 0.57 b 6.58 ± 0.20 b 0.43 ± 0.05 a 0.29 ± 0.07 a SMAO/LL 1.28 ± 0.31 c 5.58 ± 0.62 b 0.56 ± 0.04 b 0.50 ± 0.06 b SMAO/LD 0.80 ± 0.23 c 6.38 ± 0.38 b 0.57 ± 0.04 b 0.44 ± 0.03 b SMAO/NS 1.03 ± 0.12 c 5.83 ± 0.60 b 0.59 ± 0.05 b 0.49 ± 0.10 b