The Effects of Lung Ischaemia/Reperfusion on TRPM Gene Expression

ABSTRACT Objective: Transient receptor potential melastatin (TRPM) are integral membrane proteins that have broad range of cellular functions. Roles of TRPM2, TRPM3, TRPM4 and TRPM7 among these channels are very important, and their roles in lung ischaemia/reperfusion injury have not been evaluated yet. The aim of this study is to investigate the contribution of these genes in lung ischaemia/reperfusion injury and evaluate histopathology of tissues. Methods: A total of 40 Wistar albino rats were enrolled for the study. Ischaemia was performed by the application of an atramvatic clamp to pulmonary artery. Gene expressions were determined by the semi-quantitative reverse transcription-polymerase chain reaction method. Histopatholical evaluations were held by a standard haematoxyline-eosin staining. Results: The major histopathological tissue damage was observed in ischaemia performed groups, and expression of TRPM channels was found to be obviously downregulated. Substantial changes were determined between TRPM2, TRPM3, TRPM4 and TRPM7 and lung ischaemia/reperfusion injury. In particular, expression of TRPM2 and TRPM7 was reversibly downregulated in ischaemia. Yet, the expression of TRPM3 and TRPM4 was irreversibly down-regulated after ischaemia. Conclusion: Consequently, these results indicate that TRPM family of cation channels may have significant roles in the lung ischaemia/reperfusion injury.

N-(p-amylcinnamoyl) anthranilic acid attenuates remedial effects of memantine on memory deficits following intracerebroventricular streptozotocin administration in rats.

N-(p-amylcinnamoyl) anthranilic acid (ACA) is a blocker of transient receptor potential melastatin-2 (TRPM2) which is a non-selective, Ca2+-permeable and oxidative stress sensor cation channel. Intracerebroventricular (ICV) streptozotocin (STZ) induction successfully generates spatial memory deficits in rats. The purpose of this study was to investigate effects of ACA on a rat model of STZ-induced learning and memory deficits. A total of 60 Wistar rats randomly divided into six groups; (1) control, (2) sham-operated, (3) ICV-STZ administered, (4) ICV-STZ + memantine (5 mg/kg i.p.), (5) ICV-STZ + ACA (25 mg/kg i.p.) and (6) a combination therapy group, ICV-STZ + ACA (25 mg/kg) + memantine (5 mg/kg). Effects of the drugs on spatial memory deficits were appraised in Morris water maze (MWM) apparatus. Anxiety-like behavior of the rats were also assessed by using both the elevated plus maze (EPM) and open field maze (OFM) apparatuses. Western blot analysis of hippocampal tissues revealed TRPM2-L channel protein expression levels. Serum levels of tumor necrosis factor alpha (TNF-α) and malondialdehyde (MDA) were detected by enzyme-linked immunosorbent assay (ELISA) kits. Memantine treatment ameliorated the spatial memory deficits induced, as evidenced by the MWM tests. However, ACA treatment did not provide any improvement, instead positive effects of memantine were attenuated by ACA treatment. Western blot analysis in hippocampal tissues showed that TRPM2-L protein expression was markedly suppressed in ICV-STZ administered group. The ACA treatment reversed that suppression. Surprisingly, the memantine treatment resulted in overexpression of TRPM2-L, to a certain extent. Examination of the rats in EPM and OFM apparatuses, as a display of anxiety-like behavior, did not reveal any marked difference among groups. Serum levels of TNF-α and MDA also did not vary significantly among groups, as well. Conclusively, our findings showed for the first time that TRPM2-L protein expression was significantly suppressed in the ICV-STZ induced memory deficit model. Even though ACA reversed this suppression, no improvement in spatial memory was observed following ACA treatment.

Is there any association between childhood cardiac septal defects and ROCK2 gene polymorphism?

Rho/Rho-kinase pathway plays a critical role in the regulation of cellular functions such as proliferation and migration. One of the possible theories of the development of ventricular septal defects is cell migration disorder. The aim of this study was to analyze the genotype distributions and allele frequencies for the ROCK2 gene Thr431Asn polymorphisms in the development of cardiac septal defects in a Turkish population. In this case-control study, 300 patients with cardiac defects (150 patients with ventricular and 150 patients with atrial septal defects) and control group (150 healthy control subjects) were investigated. A single-nucleotide polymorphism in ROCK2 gene Thr431Asn was analyzed by real-time PCR using a Light-Cycler. Neither genotype distributions nor the allele frequencies for the Thr431Asn polymorphism showed a significant difference between the groups. These results suggest that there is no association of the ROCK2 gene Thr431Asn polymorphism with the development of cardiac septal defects in pediatric patients.

Effect of verapamil and lidocaine on TRPM and NaV1.9 gene expressions in renal ischemia-reperfusion.

BACKGROUND: To determine effects on calcium and sodium channels of Ca(2+) and Na(+) channel blockers in the present study, expression levels of TRPM1, TRPM2, TRPM3, TRPM4, TRPM5, TRPM6, TRPM7, TRPM8, and NaV1.9 genes were evaluated in kidney tissues after induced ischemia-reperfusion. MATERIAL AND METHODS: Forty albino Wistar male rats were equally divided into 4 groups as follows: group I: control group (n = 10), group II: ischemia group (60 minutes of ischemia + 48 hours of reperfusion; n = 10), group III: ischemia (60 minutes of ischemia + 48 hours of reperfusion) + calcium channel blocker (n = 8), group IV: ischemia (60 minutes of ischemia + 48 hours of reperfusion) + sodium channel blocker (n = 8). RESULTS: When compared to ischemia group expression levels of TRPM2, TRPM4, TRPM6, and NaV1.9 in Ca(2+) and Na(+) channel blocker groups were increased, whereas that of TRPM7 was decreased. However, expression levels of TRPM1, TRPM3, TRPM5, and TRPM8 were not determined in kidney tissue. Histologically, the Ca(2+) channel blocker verapamil and the Na(+) channel blocker lidocaine inhibited the cell death in kidney tissue compared to control. CONCLUSION: Our study suggested that verapamil and lidocaine significantly reduce the degree of ischemia-reperfusion injury due to effects to TRPM and Nav1.9 genes.

Effects of a selective Rho-kinase inhibitor Y-27632 on oxidative stress parameters in acute dichlorvos poisoning in rats.

This study examined the effects of Y-27632, a selective Rho-kinase inhibitor, on organophosphate-induced acute toxicity in rats. Rats were randomly divided into four groups as control (corn oil), dichlorvos (30 mg kg(-1) i.p.), 1 and 10 mg kg(-1) Y-27632 + dichlorvos groups. Cholinergic signs (fatigue, tremor, cyanosis, hyper-secretion, fasciculations) were observed in all the rats in the dichlorvos group and the mortality rate was 50%. No cholinergic findings and deaths were observed in the control and Y-27632 groups. Plasma cholinesterase activities were suppressed with dichlorvos and these reductions were attenuated with Y-27632 pretreatment. There was a marked increase in plasma malondialdehyde level in the dichlorvos group, but Y-27632 pretreatment abolished this elevation. Dichlorvos markedly depressed cardiac paraoxonase activity, but these changes were not markedly modified with Y-27632. Total antioxidant capacities, total oxidant status, oxidative stress index, total free sulfhydryl groups and catalase activities in plasma and cardiac tissues were not markedly different between the groups. No significant changes were observed with cardiac myeloperoxidase activities or plasma arylesterase and ceruloplasmin activities. In conclusion, our results suggest that Rho-kinase pathway is involved in organophosphate intoxication, and a decrease in cardiac paraoxonase activities may play a role in the pathogenesis of acute organophosphate poisoning in rats.

Effects of dexmedetomidine infusion in patients undergoing functional endoscopic sinus surgery under local anaesthesia.

BACKGROUND AND OBJECTIVES: Functional endoscopic sinus surgery can be performed under either local or general anaesthesia. The objective of this study was to investigate the haemodynamic effects of perioperatively administered dexmedetomidine, a new generation alpha-2-agonist, in patients for functional endoscopic sinus surgery. METHODS: Sixty-two patients who were planned to undergo functional endoscopic sinus surgery under local anaesthesia were included in the study. Following meperidine premedication, both groups were monitored in a standard manner with electrocardiogram, non-invasive blood pressure and percentages of peripheral saturation of oxygen. Saline intravenous infusion was started in the placebo group, and dexmedetomidine bolus intravenous infusion (an initial loading dose of 1 microg kg-1 given for a 10-min period followed by 0.7 microg kg-1 h-1) was administered to the treatment group. Maintenance dose infusion was stopped 15 min before the end of the surgical procedure. RESULTS: Systolic, diastolic and mean arterial pressures, and heart rate markedly decreased in the dexmedetomidine group. However, dexmedetomidine had no effect on serum nitric oxide levels, measured by a nitric oxide/ozone chemiluminescence method. No significant difference was found in oxygen saturation levels of the two groups. Postoperative nausea and vomiting rates were significantly lower in the dexmedetomidine group. No adverse effects were observed with this alpha-2-agonist. Dexmedetomidine provided appropriate levels of sedation. CONCLUSION: These results suggest that dexmedetomidine provides analgesia, adequate sedation and surgical comfort without adverse effects for patients undergoing functional endoscopic sinus surgery under local anaesthesia.

Cardiotoxicity of digitalis glycosides: roles of autonomic pathways, autacoids and ion channels.

1 Cardiac glycosides have been used for centuries as therapeutic agents for the treatment of heart diseases. In patients with heart failure, digoxin and the other glycosides exert their positive inotropic effect by inhibiting Na(+)-K(+)-ATPase, thereby increasing intracellular sodium, which, in turn, inhibits the Na(+)/Ca(2+) exchanger and increases intracellular calcium levels. As the therapeutic index of digitalis is narrow, arrhythmias are common problems in clinical practice. The mechanisms and mediators of these arrhythmias, however, are not completely understood. 2 The involvement of the sympathetic and parasympathetic nervous system in digitalis cardiac toxicity is reviewed. 3 Receptors, channels, exchange systems or other cellular components involved in digitalis-induced cardiotoxicity are also reviewed. 4 Possible mediators of digitalis-induced cardiac toxicity are discussed. 5 Management of digitalis toxicity in patients is summarized. 6 The determination of the possible mediators of digitalis-induced cardiac toxicity will enhance our knowledge and lead to the development of new therapeutic strategies to treat these lethal arrhythmias.