Sphingosine 1‐Phosphate (S1P) Attenuates Combined Acute Alcohol Intoxication and Hemorrhagic‐Shock/Resuscitation‐Induced Microvascular Hyperpermeability in Rat Mesentery

Abstract

Alcohol intoxication‐related injuries remain a significant clinical problem involving at least 38 million individuals and producing and estimated $223.5 billion health care cost burden in the US. In the emergency room, intoxicated trauma patients present with increased injury severity and are more hypotensive, a predictor of poor outcomes. We have previously demonstrated that acute alcohol intoxication causes microvascular hyperpermeability in vivo, and also exacerbates hemorrhagic shock/resuscitation‐ (HSR)‐induced microvascular leakage. In the current study, we tested the hypothesis that the barrier‐enhancing bioactive lipid Sphingosine 1‐Phosphate (S1P) can reverse the microvascular hyperpermeability and hypotension following combined acute alcohol intoxication and HSR. Carotid artery, jugular vein, and indwelling gastric catheters were surgically placed in anesthetized Sprague Dawley rats. Following 6–7 days recovery, conscious, unrestrained rats received 2.5 g/kg alcohol via the intragastric catheter, followed by HSR (fixed pressure of 40 mm Hg for 1 h, followed by Lactated Ringers (LR), 40% i.v. bolus + 2x total blood volume removed infusion over 1 h). During resuscitation, the rats received 0.003, 0.03, or 0.1 mg/kg S1P within the LR fluid. Following the 1‐h resuscitation phase, the rats were anesthetized for intravital microscopy of the mesenteric microcirculation. FITC‐Albumin served as a tracer to determine extravasation, quantified by measuring integrated optical intensity (IOI) of the extravascular areas adjacent to postcapillary venules. The results show that by the end of the 1‐h fluid resuscitation period, the group receiving LR supplemented with 0.1 mg/kg S1P displayed significantly restored MAP compared to Alcohol/HSR (89.1 ± 3.6 mm Hg for Alcohol/HSR + 0.1 mg/kg S1P vs. 75.2 ± 3.1 mm Hg for Alcohol/HSR, p<0.05). This trend persisted during the subsequent intravital microscopy phase of the experiment (86.3 ± 3.3 mm Hg Alcohol/HSR + 0.1 mg/kg S1P vs. 68.3 ± 4.3 mm Hg Alcohol/HSR, p<0.05). In addition, 0.1 mg/kg S1P reduced the alcohol/HSR‐induced microvascular hyperpermeability by 50% (542.3 ± 58.4 IOI units for Alcohol/HSR + 0.1 mg/kg S1P vs. 1061.7 ± 142.1 IOI units for Alcohol/HSR, p<0.001). These data show that fluid resuscitation augmented with 0.1 mg/kg S1P ameliorates alcohol/HSR‐induced hypotension and microvascular hyperpermeability more effectively than standard fluid resuscitation. Overall, the data show promise for using fluid resuscitation augmented with S1P for improving circulation in traumatic injury patients.Support or Funding InformationSupported by NIH grants R01HL098215 and R21AA020049, and the ABMRF/Foundation for Alcohol Research.