Microarray analysis of gene expression profiles in the rat kidney demonstrates a local inflammatory response induced by cardiopulmonary bypass

A Rat Model of Clinically Relevant Extracorporeal Circulation Develops Early Organ Dysfunctions

In clinical practice, extracorporeal circulation (ECC) is associated with coagulopathy and inflammation, eventually leading to organ injuries without preventive systemic pharmacological treatment. Relevant models are needed to reproduce the pathophysiology observed in humans and preclinical tests. Rodent models are less expensive than large models but require adaptations and validated comparisons to clinics. This study aimed to develop a rat ECC model and to establish its clinical relevance. One hour of veno-arterial ECC or a sham procedure were achieved on mechanically ventilated rats after cannulations with a mean arterial pressure objective > 60 mmHg. Five hours post-surgery, the rats' behavior, plasmatic/blood biomarkers, and hemodynamics were measured. Blood biomarkers and transcriptomic changes were compared in 41 patients undergoing on-pump cardiac surgery. Five hours post-ECC, the rats presented hypotension, hyperlactatemia, and behavioral alterations. The same patterns of marker measurements (Lactate dehydrogenase, Creatinine kinase, ASAT, ALAT, and Troponin T) were observed in both rats and human patients. Transcriptome analyses showed similarity in both humans and rats in the biological processes involved in the ECC response. This new ECC rat model seems to resemble both ECC clinical procedures and the associated pathophysiology, but with early organ injury corresponding to a severe phenotype. Although the mechanisms at stake in the post-ECC pathophysiology of rats or humans need to be described, this new rat model appears to be a relevant and costless preclinical model of human ECC.

Renal and Cerebral Hypoxia and Inflammation During Cardiopulmonary Bypass

Cardiac surgery-associated acute kidney injury and brain injury remain common despite ongoing efforts to improve both the equipment and procedures deployed during cardiopulmonary bypass (CPB). The pathophysiology of injury of the kidney and brain during CPB is not completely understood. Nevertheless, renal (particularly in the medulla) and cerebral hypoxia and inflammation likely play critical roles. Multiple practical factors, including depth and mode of anesthesia, hemodilution, pump flow, and arterial pressure can influence oxygenation of the brain and kidney during CPB. Critically, these factors may have differential effects on these two vital organs. Systemic inflammatory pathways are activated during CPB through activation of the complement system, coagulation pathways, leukocytes, and the release of inflammatory cytokines. Local inflammation in the brain and kidney may be aggravated by ischemia (and thus hypoxia) and reperfusion (and thus oxidative stress) and activation of resident and infiltrating inflammatory cells. Various strategies, including manipulating perfusion conditions and administration of pharmacotherapies, could potentially be deployed to avoid or attenuate hypoxia and inflammation during CPB. Regarding manipulating perfusion conditions, based on experimental and clinical data, increasing standard pump flow and arterial pressure during CPB appears to offer the best hope to avoid hypoxia and injury, at least in the kidney. Pharmacological approaches, including use of anti-inflammatory agents such as dexmedetomidine and erythropoietin, have shown promise in preclinical models but have not been adequately tested in human trials. However, evidence for beneficial effects of corticosteroids on renal and neurological outcomes is lacking. © 2021 American Physiological Society. Compr Physiol 11:1-36, 2021.

The Effect of Dexmedetomidine on Cognitive Function and Protein Expression of Aβ, p-Tau, and PSD95 after Extracorporeal Circulation Operation in Aged Rats

Postoperative cognitive dysfunction (POCD) is a kind of serious neurologic complications and dexmedetomidine has a certain effect on POCD. However, functional mechanism of dexmedetomidine on POCD still remains unclear, so the research mainly studied the effect of dexmedetomidine on cognitive function and protein expression in hippocampus and prefrontal cortex cerebrospinal fluid after extracorporeal circulation operation in aged rats. We Found that, compared with POCD group, the cognitive function was improved in POCD + Dex group. We speculate that dexmedetomidine could improve the cognitive function after extracorporeal circulation operation in aged rats and Aβ, p-Tau, and PSD95 protein might have contributed to this favorable outcome.

S1P1 receptor modulation preserves vascular function in mesenteric and coronary arteries after CPB in the rat independent of depletion of lymphocytes

Background

Cardiopulmonary bypass (CPB) may induce systemic inflammation and vascular dysfunction. Sphingosine 1-phosphate (S1P) modulates various vascular and immune responses. Here we explored whether agonists of the S1P receptors, FTY720 and SEW2871 improve vascular reactivity after CPB in the rat.

Methods

Experiments were done in male Wistar rats (total n = 127). Anesthesia was induced by isoflurane (2.5–3%) and maintained by fentanyl and midazolam during CPB. After catheterization of the left femoral artery, carotid artery and the right atrium, normothermic extracorporeal circulation was instituted for 60 minutes. In the first part of the study animals were euthanized after either 1 hour, 1 day, 2 or 5 days of the recovery period. In second part of the study animals were euthanized after 1 day of postoperative period. We evaluated the contractile response to phenylephrine (mesenteric arteries) or to serotonin (coronary artery) and vasodilatory response to acethylcholine (both arteries).

Results

Contractile responses to phenylephrine were reduced at 1 day recovery after CPB and Sham as compared to healthy control animals (Emax, mN: 7.9±1.9, 6.5±1.5, and 11.3±1.3, respectively). Mainly FTY720, but not SEW2871, caused lymphopenia in both Sham and CPB groups. In coronary and mesenteric arteries, both FTY720 and SEW2871 normalized serotonin and phenylephrine-mediated vascular reactivity after CPB (p<0.05) and FTY720 increased relaxation to acetylcholine as compared with untreated rats that underwent CPB.

Conclusion

Pretreatment with FTY720 or SEW2871 preserves vascular function in mesenteric and coronary artery after CPB. Therefore, pharmacological activation of S1P₁ receptors may provide a promising therapeutic intervention to prevent CPB-related vascular dysfunction in patients.