Efeito de dexmedetomidina sobre lesão pulmonar aguda em modelo experimental de isquemia‐reperfusão

The Effects of Dexmedetomidine and Ketamine on Oxidative Injuries and Histological Changes Following Blunt Chest Trauma

BACKGROUND

The objective of this research was to evaluate the oxidative and histopathological effects of dexmedetomidine and ketamine on the pulmonary contusion model resulting from blunt chest trauma.

METHODS

Rats were randomly assigned to 5 equal groups (n=6): control group (Group C), pulmonary contusion group (Group PC), PC-dexmedetomidine group (Group PC-D), PC-ketamine group (Group PC-K), and PC-dexmedetomidine + ketamine (Group PC-D+K). The PC was performed by dropping a weight of 500 g (2.45 Joules) from a height of 50 cm. In Group PC-D, after chest trauma, dexmedetomidine (100 µg/kg) was administered intraperitoneally. In Group PC-K, after chest trauma, ketamine (100 mg/kg) was administered intraperitoneally. In Group PC-D+K, dexmedetomidine and ketamine were administered together. At the end of the 6th hour, rats were sacrificed. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activities, neutrophil infiltration/aggregation, and thickness of the alveolar wall were evaluated.

RESULTS

MDA levels were significantly higher in Group PC than Groups C, PC-D, and PC-D+K. SOD enzyme activity was significantly higher in Group PC than Groups C, PC-D, and PC-D+K. In addition, neutrophil infiltration/aggregation and total pulmonary injury scores were significantly higher in Group PC than in other groups, and the thickness of the alveolar wall was significantly higher in Group PC compared to Groups C, PC-D, and PC-D+K. MDA level, SOD enzyme activities, neutrophil infiltration/aggregation, and thickness of alveolar wall were similar in PC-D and PC-D+K groups.

CONCLUSION

Dexmedetomidine and dexmedetomidine+ketamine have protective effects on blunt chest trauma but no protective effect was observed when ketamine was administered alone. We concluded that the administration of dexmedetomidine and ketamine after contusion is beneficial against pulmonary injury in rats.

Pre-cardiopulmonary bypass administration of dexmedetomidine decreases cardiac troponin I level following cardiac surgery with sevoflurane postconditioning

Objective

This study was performed to determine the effect of dexmedetomidine (DEX) administration on myocardial damage in cardiac surgery with sevoflurane postconditioning.

Methods

We retrospectively examined all cardiac valve replacement surgeries from 1 April 2016 to 30 April 2017. Eligible patients were divided into two groups based on whether DEX was infused. DEX infusion was permitted only between intubation and the beginning of cardiopulmonary bypass (CPB). Sevoflurane was inhaled via the standard postconditioning procedure starting at aortic declamping. The cardiac troponin I (cTnI) level was measured at different time points. The postoperative outcomes and complications were also analyzed.

Results

One hundred patients were included in the study (DEX group, n = 53; non-DEX group, n = 47). Increased cTnI levels were significantly correlated with the New York Heart Association classification, CPB time, and DEX use. DEX use and the CPB time were potential independent factors contributing to changes in the cTnI level. The cTnI level at 6, 12, and 24 hours postoperatively was remarkably lower in the DEX than non-DEX group by 1.14, 7.83, and 5.86 ng/mL, respectively.

Conclusions

DEX decreased the cTnI level after CPB when sevoflurane postconditioning was used, especially at 6, 12, and 24 hours postoperatively.

miR‑223‑3p/TIAL1 interaction is involved in the mechanisms associated with the neuroprotective effects of dexmedetomidine on hippocampal neuronal cells in vitro

Dexmedetomidine (DEX), an α2 adrenoceptor agonist, is a commonly used anesthetic drug in surgical procedures. Previous studies have indicated that DEX exerts neuroprotective effects. However, the molecular mechanism underlying this process remains to be elucidated. The present study investigated a potential implication of microRNA (miR)-223-3p in the DEX-induced anti-oxidative effect on neuronal cells. The results indicated that following hydrogen peroxide (H₂O₂)-mediated induction of oxidative stress, the viability of human hippocampal neuronal cells was markedly decreased, as determined by an MTT assay. In addition, treatment with H₂O₂ induced cell apoptosis, the release of lactate dehydrogenase, accumulation of intracellular calcium, phosphorylation of calmodulin-2, and production of malondialdehyde and reactive oxygen species. Furthermore, treatment with H₂O₂ inhibited the expression of mir-223-3p and enhanced the expression of its target cytotoxic granule associated RNA binding protein like 1 (TIAL1), and these effects were reversed by treatment with DEX. Mechanistic studies demonstrated that the 3′-untranslated region of TIAL1 is a direct target of mir-223-3p. The results of the present study demonstrated that DEX may induce its neuroprotective effects by regulating the interaction between miR-223-3p and TIAL1. Therefore, the manipulation of miR-223-3p/TIAL1 interaction may be involved in the neuroprotective effects of DEX.

Effect of iloprost on contractile impairment and mitochondrial degeneration in ischemia-reperfusion of skeletal muscle

Purpose Acute lower extremity ischemia is still a main cause of mortality and morbidity in orthopedic traumatology and reconstructive surgery. In acute lower extremity ischemia, the skeletal muscles are the tissues that are the most vulnerable to ischemia. The aim of this study was to evaluate the effects of iloprost (IL) therapy on skeletal muscle contractile impairment and mitochondrial degeneration in an acute lower extremity ischemia-reperfusion rat model. Main Methods Forty Wistar albino rats were randomly divided into a control group and four experimental groups. Experimental groups were either subjected to 2 h of lower extremity ischemia followed by a 4-h reperfusion period or to 4 h of ischemia followed by an 8-h reperfusion period. Except for the animals in the control group, all animals received IL (1 ng/kg/min) or saline (1 ml/kg) by intraperitoneal infusion for 10 min immediately before reperfusion. At the end of the recording of skeletal muscle electrical activity and contractility, all rats were sacrificed by decapitation and muscle samples of lower extremity were immediately harvested for histopathologic analyses. Results After ischemia-reperfusion, a breakdown in the force-frequency curves of extensor digitorum longus muscle was observed, showing the diminished muscle contractility. However, IL significantly improved muscle contractility following injury induced by 2 h of ischemia followed by a 4-h reperfusion period. In addition, IL partially ameliorated mitochondrial degeneration in the muscle cells of ischemia groups. Conclusion This study indicates that immediate IL therapy repairs muscle damage especially after 2 h of ischemia and 4 h of reperfusion and therefore that IL improves contractile function.