Post-ischemic infusion of atrial natriuretic peptide attenuates warm ischemia-reperfusion injury in rat lung

Real-time lung weight measurement during clinical ex vivo lung perfusion

BACKGROUND

Real-time lung weight (LW) measurement is a simple and noninvasive technique for detecting extravascular lung water during ex vivo lung perfusion (EVLP). We investigated the feasibility of real-time LW measurement in clinical EVLP as a predictor of transplant suitability and post-transplant outcomes.

METHODS

In our clinical acellular EVLP protocol, real-time LW was measured in 117 EVLP cases from June 2019 to June 2022. The estimated LW gain at each time point was calculated using a scale placed under the organ chamber. The lungs were classified into 4 categories based on LW adjusted for height and compared between suitable and unsuitable cases. The relationship between estimated LW gain and primary graft dysfunction was also investigated.

RESULTS

The estimated LW gain during the EVLP significantly correlated with the LW gain (post-EVLP LW and pre-EVLP LW) measured on the back table (R2 = 0.61, p < 0.01). In the adjusted LW categories 2 to 4, the estimated LW gain at 0-1 hour after EVLP was significantly higher in unsuitable cases than in suitable cases. The area under the curve for the estimated LW gain was ≥0.80. Primary graft dysfunction grades 0 to 1 had a significantly lower estimated LW gain at 60 minutes than grades 2 to 3 (-43 vs 1 g, p < 0.01).

CONCLUSIONS

Real-time lung measurements can predict transplant suitability and post-transplant outcomes by the early detection of extravascular lung water during the initial 1 hour of EVLP.

Therapeutic role of atrial natriuretic peptide in early treatment of traumatic hemorrhagic shock

The biological effect of atrial natriuretic peptide (ANP) in traumatic hemorrhagic shock (THS) is unknown. This study was to evaluate whether ANP therapy can show organ protection in THS. Thirty male Sprague-Dawley rats were divided into three groups: ANP group, sham group, and control group. Pressure-controlled THS was induced in rats in ANP group and control group. ANP at a rate of 0.025 μg/kg/min was infused in ANP group during near-80 min of shock. After that, animals were resuscitated for 60 min and observed until 24 h. Hemodynamic parameters during shock and resuscitation were measured. Serum levels of ANP and lactate dehydrogenase, tissue oxidative stress and inflammatory factors, as well as liver and kidney function were determined. Tissue apoptosis was also assessed. There was no statistically significant difference between ANP group and control group in arterial pressure throughout the 150 min monitoring period. Blood urea nitrogen at 90 min and 24 h in ANP group was significantly lower than control group. Alanine transaminase and aspartate aminotransferase activity at 90 min in control group were significantly higher than that in sham group. However, hepatic enzyme activity at 90 min in ANP group was not significantly different compared with sham or control group. After 24 h, myocardial expression of caspase 3 protein in ANP group was significantly reduced compared with control group. Jejunal and hepatic Malondialdehyde was increased following ANP treatment. ANP therapy during early THS has no significant adverse effect on hemodynamics but can exert oxidative stress and certain protective effect on multiple organs. Our study may shed light on the novel therapy of THS with regard to organ protection. The mechanisms underlying the organ protection require further study.

Human Atrial Natriuretic Peptide in Cold Storage of Donation After Circulatory Death Rat Livers: An Old but New Agent for Protecting Vascular Endothelia?

BACKGROUND

Current critical shortage of donor organs has increased the use of donation after circulatory death (DCD) livers for transplantation, despite higher risk for primary nonfunction or ischemic cholangiopathy. Human atrial natriuretic peptide (hANP) is a cardiovascular hormone that possesses protective action to vascular endothelia. We aimed to clarify the therapeutic potential of hANP in cold storage of DCD livers.

METHODS

Male Wistar rats were exposed to 30-minute warm ischemia in situ. Livers were then retrieved and cold-preserved for 6 hours with or without hANP supplementation. Functional and morphological integrity of the livers was evaluated by oxygenated ex vivo reperfusion at 37°C.

RESULTS

hANP supplementation resulted in significant reduction of portal venous pressure (12.2 ± 0.5 versus 22.5 ± 3.5 mm Hg, P < 0.001). As underlying mechanisms, hANP supplementation significantly increased tissue adenosine concentration (P = 0.008), resulting in significant upregulation of endothelial nitric oxide synthase and significant downregulation of endothelin-1 (P = 0.01 and P = 0.004 vs. the controls, respectively). Consequently, hANP significantly decreased transaminase release (P < 0.001) and increased bile production (96.2 ± 18.2 versus 36.2 ± 15.2 μL/g-liver/h, P < 0.001). Morphologically, hepatocytes and sinusoidal endothelia were both better maintained by hANP (P = 0.021). Electron microscopy also revealed that sinusoidal ultrastructures and microvilli formation in bile canaliculi were both better preserved by hANP supplementation. Silver staining also demonstrated that hANP significantly preserved reticulin fibers in Disse space (P = 0.017), representing significant protection of sinusoidal frameworks/architectures.

CONCLUSIONS

Supplementation of hANP during cold storage significantly attenuated cold ischemia/warm reperfusion injury of DCD livers.

The effect of atrial natriuretic peptide infusion on intestinal injury in septic shock

BACKGROUND AND AIMS

The aim of this study is to assess the effect of atrial natriuretic peptide (ANP) on intestinal ischemia-reperfusion injury in septic shock.

MATERIAL AND METHODS

A prospective randomized controlled, observer-blinded study was carried out in surgical Intensive Care Unit (ICU), University Hospital. Forty adult patients in septic shock were randomly divided into two groups, control group (Group C) received normal saline and ANP group (Group A) patients received ANP in the form of 1.5 mg vial added to 250 ml solvent in plastic bag (1 ml = 6 micg) given at 2 mcg/kg intravenous bolus over 1 min followed by 0.01 mcg/kg/min for 24 h. The primary outcome measurements were blood marker of intestinal hypoperfusion in form of intestinal fatty acid binding protein (I-FABP), malondialdehyde (MDA), myloperoxidase enzyme activity (MPO), protein carbonyl (PC), and glutathione peroxidase activity (GPA) measured before start of ANP infusion, 6 h, 12 h, and 24 h after start of infusion. The secondary outcome measurements were the duration of noradrenaline infusion, duration of ICU stay, hospital mortality rate, and complications related to ANP.

RESULTS

In comparison with Group C, Group A showed a significant decrease (P < 0.05) in serum level of MPO, MDA, PC, and I-FABP, with a significant increase (P < 0.05) in serum level of GPA, 6 h, 12 h, and 24 h after the start of ANP infusion. There was significant decrease (P < 0.05) in mean duration of noradrenaline infusion, the length of ICU stay and mortality rate in Group A in comparison with Group C. In Group A, seven patients had mean arterial blood pressure < 65 mmHg but respond to volume resuscitation, three patients serum sodium was 125-130 mmol/L.

CONCLUSION

In cases of septic shock, concomitant administration of ANP with noradrenaline may have a protective effect against intestinal injury through a decrease in the level of intestinal hypoperfusion owing to its anti-inflammatory and antioxidant effect.

Therapeutic effect of surfactant inhalation during warm ischemia in an isolated rat lung perfusion model

Warm ischemia-reperfusion injury related to donation after cardiac death donors is a crucial and inevitable issue. As surfactant function is known to deteriorate during warm ischemia, we hypothesized that surfactant inhalation during warm ischemia would mitigate warm ischemia-reperfusion injury. We used an isolated rat lung perfusion model. The rats were divided into three groups: sham, control, and surfactant. In the control and surfactant groups, cardiac arrest was induced by ventricular fibrillation. Ventilation was restarted 110 min later; subsequently, the lungs were flushed, and heart and lung block was recovered. In the surfactant group, a natural bovine surfactant Surfacten(®) was inhaled for 3 min at the end of warm ischemia. Then, the lungs were reperfused for 80 min. Surfactant inhalation significantly improved graft functions, effectively increased lung tissue ATP levels, and significantly decreased mRNA levels of IL-6 and IL-6/IL-10 ratio at the end of reperfusion. Histologically, lungs in the surfactant group showed fewer signs of interstitial edema and hemorrhage, and significantly less neutrophilic infiltration than those in the control group. Our results indicated that surfactant inhalation in the last phase of warm ischemia maintained lung tissue energy levels and prevented cytokine production, resulting in the alleviation of warm ischemia-reperfusion injury.

Hypothermic machine perfusion ameliorates ischemia-reperfusion injury in rat lungs from non-heart-beating donors

BACKGROUND

The use of non-heart-beating donors (NHBD) has come into practice to resolve the shortage of donor lungs. This study investigated whether hypothermic machine perfusion (HMP) can improve the quality of NHBD lungs.

METHODS

An uncontrolled NHBD model was achieved in male Lewis rats. Ninety minutes after cardiac arrest, HMP was performed for 60 min at 6°C to 10°C. The first study investigated the physiological lung functions during HMP and the lung tissue energy levels before and after HMP. The second study divided the rats into three groups (n=6 each): no ischemia group; 90-min warm ischemia+60-min HMP+120-min static cold storage (SCS) (HMP group); and 90-min warm ischemia+180-min SCS group. All lungs were reperfused for 60 min at 37°C. Lung functions were evaluated at given timings throughout the experiments. Oxidative damage during reperfusion was evaluated immunohistochemically with a monoclonal antibody against 8-hydroxy-2'-deoxyguanosine.

RESULTS

The first study revealed that lung functions were stable during HMP. Lung tissue energy levels decreased during warm ischemia but were significantly increased by HMP (P<0.05). The second study confirmed that HMP significantly decreased pulmonary vascular resistance, increased pulmonary compliance, and improved pulmonary oxygenation. The ratio of 8-hydroxy-2'-deoxyguanosine positive cells to total cells significantly increased in the SCS group (P<0.01).

CONCLUSIONS

Short-term HMP improved lung tissue energy levels that decreased during warm ischemia and ameliorated ischemia-reperfusion injury with decreased production of reactive oxygen species.

Modelo experimental de perfusão pulmonar isolada em ratos: técnica e aplicações em estudos de preservação pulmonar

Estudos de preservação pulmonar em modelos experimentais realizados em animais de pequeno porte são de realização mais simples e barata. Esta comunicação tem o enfoque de descrever tecnicamente um modelo de perfusão pulmonar ex vivo em ratos, com o uso de um equipamento disponível comercialmente que foi o primeiro a ser instalado em um laboratório de pesquisa em cirurgia torácica no Brasil. Descrevemos detalhadamente o modelo e sua preparação, assim como suas aplicações para estudos de preservação pulmonar. Os detalhes técnicos da preparação podem ser observados também em um vídeo postado no site do Jornal Brasileiro de Pneumologia.

Endocrine heart after lung transplantation: increased brain natriuretic peptide is related to right ventricular function

Brain natriuretic peptide (BNP) increases in proportion to the extent of right ventricular dysfunction in pulmonary hypertension and after heart transplantation. No data are available after lung transplantation. Clinical, biological, respiratory, echocardiographic characteristics and circulating BNP and its second messenger cyclic guanosine monophosphate (cGMP) were determined in thirty matched subjects (10 lung-, 10 heart-transplant recipients (Ltx, Htx) and 10 healthy controls). Eventual correlations between these parameters were investigated. Heart rate and pulmonary arterial blood pressure were slightly increased after transplantation. Creatinine clearance was decreased. Mean of forced expiratory volume in 1 s was 76.6 +/- 5.3% and vital capacity was 85.3 +/- 6.4% of the predicted values in Ltx. BNP was similarly increased in Ltx and Htx, as compared with control values (54.1 +/- 14.2 and 45.6 +/- 9.2 vs. 6.2 +/- 1.8 pg/ml, respectively). Significant relationships were observed between plasma BNP and cGMP values (r = 0.62; P < 0.05 and r = 0.75; P < 0.01, in Ltx and Htx) and between BNP and right ventricular fractional shortening and tricuspid E/Ea ratio in Ltx (r = -0.75 and r = 0.93; P < 0.01, respectively). BNP is increased after lung transplantation, like after heart transplantation. The relationships observed suggest that the cardiac hormone might counterbalance possible deleterious effects of lung-transplantation on right functioning of patient's heart.