ABSTRACT
<p><b>BACKGROUND</b>Opioid preconditioning (PC) reduces anoxia/reoxygenation (A/R) injury to various cells. However, it remains unclear whether opioid-induced delayed PC would show anti-apoptotic effects on pulmonary artery endothelial cells (PAECs) suffering from A/R injury. The present study was conducted to elucidate this issue and to investigate the potential mechanism of opioid-induced delayed PC.</p><p><b>METHODS</b>Cultured porcine PAECs underwent 16-hour anoxia followed by 1-hour reoxygenation 24 hours after pretreatment with saline (NaCl; 0.9%) or morphine (1 micromol/L). To determine the underlying mechanism, a non-selective K(ATP) channel inhibitor glibenclamide (Glib; 10 micromol/L), a nitric oxide (NO) synthase blocker NG-nitro-L-arginine methyl ester (L-NAME; 100 micromol/L), and an opioid receptor antagonist naloxone (Nal; 10 micromol/L) were given 30 minutes before the A/R load. The percentage of apoptotic cells was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. eNOS mRNA level was measured by real-time polymerase chain reaction (PCR). NO content of PAECs supernatants was measured with the Griess reagent.</p><p><b>RESULTS</b>Compared to the A/R PAECs, morphine-induced delayed PC significantly reduced PAECs apoptosis ((18.1 +/- 1.9)% vs (5.5 +/- 0.3)%; P < 0.05), increased NO release ((11.4 +/- 1.3) micromol/L vs (20.5 +/- 2.1) micromol/L, P < 0.05), and up-regulated eNOS gene expression nearly 9 times (P < 0.05). The anti-apoptosis effect of morphine was abolished by pretreatment with Glib, L-NAME and Nal, but the three agent-selves did not aggravate the A/R injury. Furthermore, L-NAME and Nal offset the enhanced release of NO caused by pretreatment with morphine.</p><p><b>CONCLUSIONS</b>Morphine-induced delayed PC prevents A/R injury of PAECs. This effect may be mediated by activation of K(ATP) channel via opioid receptor and NO signaling pathways.</p>
Subject(s)
Animals , Analgesics, Opioid , Pharmacology , Apoptosis , Cell Hypoxia , Cells, Cultured , Endothelial Cells , Cell Biology , Metabolism , Enzyme Inhibitors , Pharmacology , Glyburide , Pharmacology , In Situ Nick-End Labeling , Morphine , Pharmacology , NG-Nitroarginine Methyl Ester , Pharmacology , Naloxone , Pharmacology , Narcotic Antagonists , Pharmacology , Nitric Oxide , Metabolism , Nitric Oxide Synthase Type III , Genetics , Metabolism , Oxygen , Pharmacology , Pulmonary Artery , Cell Biology , RNA, Messenger , Genetics , Metabolism , Reverse Transcriptase Polymerase Chain Reaction , SwineABSTRACT
<p><b>BACKGROUND</b>Successful lung transplantation has been limited by the scarcity of donors. Brain death (BD) donors are major source of lung transplantation. Whereas BD process induces acute lung injury and aggravates lung ischemia reperfusion injury. Carbon monoxide (CO) inhalation at 50-500 parts per million (ppm) can ameliorate lung injury in several models. We examined in rats whether CO inhalation in BD donor would show favorable effects on lung grafts.</p><p><b>METHODS</b>Rats were randomly divided into 4 groups. In sham group, donor rats received insertion of a balloon catheter into the cranial cavity, but the balloon was not inflated. In BD-only group, donor rats were ventilated with 40% oxygen after BD confirmation. In BD+CO250 and BD+CO500 groups, donor rats inhaled, after BD confirmation, 250 ppm or 500 ppm CO for 120 minutes prior to lung procurement, and orthotopic lung transplantation was performed. The rats were sacrificed 120 minutes after the lung transplantation by exsanguination, and their blood and lung graft samples were obtained. A total of 8 rats fulfilling the criteria were included in each group.</p><p><b>RESULTS</b>The inhalation decreased the severity of lung injury in grafts from BD donors checked by histological examination. CO pretreatment reversed the aggravation of PaO2/FiO2 in recipients from BD donors. The CO inhalation down-regulated pro-inflammatory cytokines (TNF-alpha, IL-6) along with the increase of anti-inflammatory cytokine (IL-10) in recipient serum, and inhibited the activity of myeloperoxidase in grafts tissue. The inhalation significantly decreased cell apoptosis in lung grafts, inhibiting mRNA and protein expression of intercellular adhesion molecule-1 (ICAM-1) and caspase-3 in lung grafts. Further, the inhalation activated phosphorylation of p38 expression and inhibited phosphorylation of anti-extracellular signal-regulated kinase (ERK) expression in lung grafts. The effects of CO at 500 ppm were greater than those at 250 ppm.</p><p><b>CONCLUSIONS</b>CO exerts potent protective effects on lung grafts from BD donor, exhibiting anti-inflammatory and anti-apoptosis functions by modulating the mitogen-activated protein kinase (MAPK) signal transduction.</p>