ABSTRACT
Objective To investigate the effects of limb ischemic post-conditioning (LIpostC) alone or its combination with therapeutic hypothermia (TH) on systemic inflammatory response and lung injury after cardiac arrest (CA) and resuscitation. Methods Twenty-one healthy male pigs weighing (37±2) kg were randomly divided into 3 groups (n = 7 each): control group, LIpostC group, and LIpostC+TH group. The animal model was established by 10 minutes of untreated CA and then 5 minutes of cardiopulmonary resuscitation (CPR).Coincident with the start of CPR, LIpostC was induced by four cycles of 5 minutes of limb ischemia followed by 5 minutes of reperfusion in the LIpostC and LIpostC+TH groups. After successful resuscitation, TH was implemented by surface cooling to reach a temperature of 32-34℃ until 4 hours post-resuscitation, followed by a re-warming rate of 1 ℃/h for 4 hours in the LIpostC+TH group. Normal temperature was maintained in the control and LIpostC groups. The resuscitation outcomes in each group were recorded during CPR. At 15 minutes prior to CA (baseline) and during 4 hours post-resuscitation, the level of arterial lactate was measured and PaO2/FiO2 was calculated, and extra-vascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were measured meanwhile by a PiCCO monitor. At 15 minutes prior to CA (baseline) and during 24 hours post-resuscitation, the levels of serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured by enzyme linked immunosorbent assay (ELISA). Results Six animals in each group were successfully resuscitated. Coronary perfusion pressure (CPP), duration of resuscitation, number of shocks and epinephrine dosage during CPR were not statistically significant among the three groups. The baseline of arterial lactate, PaO2/FiO2, EVLWI, PVPI and cytokines prior to CA were also not statistically significant among the three groups. The levels of serum TNF-α and IL-6 after resuscitation were gradually increased in all the three groups; however, the values of TNF-αand IL-6 were significantly lower in the LIpostC and LIpostC+TH groups than that in the control group, and they were further decreased in the LIpostC+TH group when compared to the LIpostC group [TNF-α (ng/L): 305±22 vs. 343±26 at 4 hours, 350±29 vs. 389±18 at 24 hours; IL-6 (ng/L): 239±14 vs. 263±19 at 24 hours, all P < 0.05]. The levels of lactate reached the peak at 2 hours post-resuscitation and then gradually decreased in all the three groups; it finally returned to the baseline in the LIpostC and LIpostC+TH groups, which was markedly lower than that in the control group (mmol/L: 1.4±0.7, 1.2±0.3 vs. 3.1±1.7, both P < 0.05). During 4 hours post-resuscitation, PaO2/FiO2 was significantly higher and EVLWI and PVPI were markedly lower in the LIpostC and LIpostC+TH groups than that in the control group; additionally, PaO2/FiO2 and EVLWI were further improved in the LIpostC+TH group than the LIpostC group [4-hour PaO2/FiO2 (mmHg, 1 mmHg = 0.133 kPa): 391±26 vs. 361±20; 4-hour EVLWI (mL/kg): 10.1±1.5 vs. 12.1±1.2, both P < 0.05]. Conclusion LIpostC can be used to alleviate systemic inflammatory response and lung injury after porcine CA and CPR, and its combination with TH further enhanced its protective effects.
ABSTRACT
Objective To investigate the protective effect of Limb ischemic postconditioning ( LIPostC) on blood brain barrier (BBB) and explore the influence on the the expression of tight junction protein claudin-5,occludin in cerebral ischemia-reperfusion injury of mice.Methods Ninety male CD1 mice were divided into three groups randomly:Sham-operated group(sham group), ischemia-reperfusion group(I/R group) and LIPostC group.Mouse middle cerebral artery cerebral ischemia-reperfusion model was established by modified-occlusion method. Neurological deficit scores, brain water content, infarct volume, BBB dysfunction were measured at 24 h after reperfusion.Western blot and RT-qPCR were used to analyze the expressions of claudin-5, occludin.Results Compared with I/R group, neurological deficits scores were significantly decreased, brain edema was relieved, infarct volume was reduced, and the expression of claudin-5, occludin up-regulated, the differences were statistically significant(all P<0.05).Conclusion LIPostC can protect the BBB of cerebral ischemia-reperfusion injury mice by increasing the expression of claudin-5,occludin, and that will provide a theoretical basis for its clinical application.
ABSTRACT
Limb remote ischemic postconditioning (LRIP) can reduce ischemia-reperfusion injury (IRI), but its mechanisms are still unclear. We hypothesize that LRIP reduces IRI by reversing eNOS uncoupling. Focal ischemia was induced in Sprague-Dawley rats by middle cerebral artery occlusion for 2 h followed by a 24 h reperfusion. Before this surgery, folic acid (FA) was administered to the drug treatment group by gavage for 11 days. After a 24 h reperfusion, behavioural testing, vascular function, NO concentration and superoxide dismutase activity in the serum were determined. In addition, the infarct size of the brain was also detected. The mRNA of eNOS, nNOS, GTP cyclohydrolase I (GTPCH), P22phox and xanthine oxidase (XO) in the ischemic region were detected by RT-PCR, and nitrotyrosine (Tyr-NO2) was detected using Western blot analysis. The results showed that LRIP, FA and FA+LRIP all could improve behavioural score, and increase NO–mediated endothelium-dependent vasomotor responses, reduce infarction of rats subjected to IRI. Western blot and RT-PCR analyses showed that the Tyr-NO2 levels and the mRNA expression of NADPH oxidase catalytic subunit P22phox and XO were up-regulated in the ischemic brain, which was significantly inhibited by LRIP, FA and FA+LRIP. The mRNA expression of the rate-limiting enzyme in BH4 synthesis, GTPCH, was down-regulated in the ischemic brain, which could be significantly augmented by LRIP and FA+LRIP. It can be concluded that IRI induces eNOS uncoupling in the cerebral ischemic region and LRIP partially reverses the eNOS uncoupling induced by IRI.