S40 Surgical Forum Abstracts J Am Coll Surg

mice. These findings were confirmed by inhibiting the P2X7 receptorwith oxi-ATP (40 mg/kg i.p.). Inhibition of P2X7 receptors led to

increased bacterial burden, cytokine and chemokine levels in septicshock. P2X7KO/P2X7WT bone marrow chimeras exhibitedhigher cytokine and chemokine levels than P2X7WT/P2X7WT

mice. Septic P2X7KO mice had excessive apoptosis in the thymusand increased inflammation in the heart and lung.

CONCLUSIONS: Our findings that P2X7 receptor inactivationleads to higher mortality and cell death in sepsis suggest that

perhaps stimulation of this signaling pathway could convey a pro-tective benefit.

Microvascular Acclimatization to Chronic HypoxiaAttenuates Microvascular Hyperpermeability afterHemorrhagic Shock/Resuscitation via Inducible NitricOxide Synthase (iNOS)Jessica LHogan,MD, JohnWood,PhD, JamesMHoward,MD,FACS,Michael Moncure, MD, FACSUniversity of Kansas Medical Center, Kansas City, KS

INTRODUCTION: Development of microvascular hyperpermeabil-

ity after hemorrhagic shock/resuscitation results in edema in sys-temic organs. We have shown that acute systemic hypoxiaincreases vascular permeability, yet this response resolves during

chronic hypoxia in part due to expression of iNOS. Our goalwas to determine if chronic hypoxia attenuates hyperpermeabilityafter hemorrhagic shock/resuscitation, and if iNOS is involved.

METHODS: Mesenteric venules of anesthetized rats were examined

using intravital microscopy. Rats were acclimatized to hypobaric hyp-oxia for 1 week at a level equivalent to 10% inspired O2. Hemorrhag-ic shock was induced by blood withdrawal tomaintain blood pressure

at 40 mmHg for 60 min followed by resuscitation for 2 h. FITC-al-bumin was used to determine a vascular permeability index (VPI)based on the ratio of extravascular to intravascular fluorescence. Re-

sponses were compared in non-acclimatized and acclimatized rats.

RESULTS: VPI increased after hemorrhagic shock/resuscitation innon-acclimatized rats (control: 0.12�0.03, resuscitation:0.76�0.08, p<0.05, n¼6). After shock/resuscitation, VPI was signif-

icantly lower in acclimatized rats (0.26�0.05, n¼5) compared tonon-acclimatized rats (p<0.05). The iNOS inhibitor L-NIL signifi-cantly increased VPI after resuscitation in acclimatized rats

(0.44�0.06, n¼6) vs vehicle-treated acclimatized rats (p<0.05).L-NIL had no statistically significant effect on VPI in non-acclima-tized rats (n¼5). Levels of iNOS protein were significantly increasedin mast cells of acclimatized vs non-acclimatized rats.

CONCLUSIONS: Chronic hypoxia attenuates microvascularhyperpermeability after hemorrhagic shock/resuscitation in partthrough expression of iNOS in mast cells. A better understanding

of acclimatization to hypoxia may lead to novel interventions toreduce microvascular inflammation in clinical settings.

Tissue Inhibitor of Metalloproteinases-2 (TIMP2) InhibitsHemorrhagic Shock (HS)-Induced VascularHyperpermeabilityKatie C Wiggins-Dohlvik, MD, Hayden W Stagg, MD,Chinchusha Anasooya Shaji, Ryan P Oakley, BA,Himakarnika Alluri, MS, Dhriti Mukhopadhyay, MD,Lena Perger, MD, Matthew L Davis, MD, Binu Tharakan, PhDBaylor Scott and White Memorial Hospital, Temple, TX, TexasA&M Health Science Center College of Medicine, Temple, TX

INTRODUCTION: HS incites global ischemia and microvascularhyperpermeability. Endothelial dysfunction is paramount therein.We hypothesized matrix metalloproteinases (MMPs) are important

in HS-induced vascular hyperpermeability and subsequent de-rangements could be mitigated with the use of TIMP2.

METHODS: SD rats were divided into sham, HS, and HS+TIMP2

(HS for1hour). Laparotomywas performedandmesenteric post capil-lary venules were examined with intravital microscopy. Fluorescent in-tensities were measured intravascularly and extravascularly, fluid

requirements were recorded, and serum and tissue were collected.Rat lung microvascular endothelial cells (RLMEC) were grown asmonolayers. Sham serum, HS serum, sham serum+TIMP2, and HS

serum+TIMP2 were applied. Albumin flux across the monolayer wasobtained. SeparateRLMECwere grown on chamber slides and stainedfor adherens junction protein b-catenin and the cytoskelatal protein F-actin. Confocal microscopy images were captured. MMP activity wasassayed in lung tissue homogenates from experimental animals. Statis-tical analysis was conducted using Student’s t-test and ANOVA.

RESULTS: Intravital microscopy revealed a significant increase invascular hyperpermeabilty after HS, which was mitigated withTIMP2 administration. Fluid requirements were significantly

improved when TIMP2 was administered. Monolayer permeabilitywas increased with HS serum and this was mitigated with TIMP2.HS serum damaged RLMEC adherens junctions and increased F-actin stress fibers; integrity was preserved in both with TIMP2

treatment. MMP activity was increased in HS rat lung and signif-icantly decreased in the HS+TIMP2 group.

CONCLUSIONS: HS damages adherens junctions and increases

monolayer permeability in vitro, and increases MMP activity andvascular permeability in vivo. TIMP2 attenuates such derangements.

Mild Systemic Zinc Imbalance Delays Recovery in aMouse Model of Surgically-Induced Ileus: Is it Driven byDisturbances in the Cytokine Network or Pro-Inflammatory Components of the Lipidome?Abby K Geletzke, MD, Brett E Phillips, PhD, Philip B Smith, PhD,Abigail B Podany, MD, Shannon L Kelleher, PhD,Andrew D Patterson, PhD, David I Soybel, MD, FACSPenn State Milton S. Hershey Medical Center, Hershey, PA

INTRODUCTION: Mild zinc (Zn) imbalance is common in pa-tients with chronic illness and cancer, and may impair convales-

cence and healing after major abdominal operations. Here, weexplore the influence of mild dietary Zn deprivation on systemic