PI3K-AKT Pathway Protects Cardiomyocytes Against Hypoxia-Induced Apoptosis by MitoKATP-Mediated Mitochondrial Translocation of pAKT.

Background/aims: The phosphatidylinositol-3-kinase -AKT (PI3K-AKT) is an important intracellular signal pathway in regulating cell proliferation, differentiation and apoptosis. In previous studies, we've demonstrated that PI3K-AKT pathway protects cardiomyocytes from ischemic and hypoxic apoptosis through mitochondrial function. However, the molecular mechanisms underlying hypoxia-induced cardiomyocyte apoptosis via PI3K-AKT pathway remain ill-defined.

Early application of continuous high-volume haemofiltration can reduce sepsis and improve the prognosis of patients with severe burns.

Background: In the early stage of severe burn, patients often exhibit a high level of inflammatory mediators in blood and are likely to develop sepsis. High-volume haemofiltration (HVHF) can eliminate these inflammatory mediators. We hypothesised that early application of HVHF may be beneficial in reducing sepsis and improving the prognosis of patients with severe burns.

Protective effects of enalapril, an angiotensin-converting enzyme inhibitor, on multiple organ damage following scald injury in rats.

The aim of this study is to investigate the effects of enalapril, an angiotensin-converting enzyme inhibitor, on multiple organ damage after scald injury. Healthy adult rats (half male and half female; 8-12 weeks old) were randomly assigned to the following treatments: sham operation, scald injury, and intraperitoneal enalapril (1, 2, and 4 mg/kg body weight) treatment after scalding. At 1, 12, and 24 H postscald, left ventricular and aortic hemodynamics were measured using a multichannel physiological recorder.

MAP4 mechanism that stabilizes mitochondrial permeability transition in hypoxia: microtubule enhancement and DYNLT1 interaction with VDAC1.

Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption.

Prompt myocardial damage contributes to hepatic, renal, and intestinal injuries soon after a severe burn in rats.

Background: Ischemic/hypoxic myocardial damage and functional impairment of the myocardium occurs immediately after major burns. This experimental study investigated whether the prompt cardiac dysfunction initiates hepatic, renal, and intestinal injuries soon after a severe burn.

Methods: Wistar rats were randomized to a sham burn group, a burn group (subjected to 30% total body surface area third-degree burn) that was subdivided into two groups: a simple burn group, observed at 0.

[Influence of microtubule depolymerization of myocardial cells on mitochondria distribution and energy metabolism in adult rats].

Objective: To investigate the influence of microtubule depolymerization of myocardial cells on distribution and activity of mitochondria, and energy metabolism of cells in adult rats.

Methods: Myocardial cells of SD adult rats and SD suckling rats were isolated and cultured. They were divided into adult and suckling rats control groups (AC and SC, normally cultured without any stimulating factor), adult and suckling rats microtubule depolymerization agent groups (AMDA and SMDA, cultured with 8 micromol/L colchicine containing nutrient solution for 30 minutes) according to the random number table.

Microtubular stability affects cardiomyocyte glycolysis by HIF-1alpha expression and endonuclear aggregation during early stages of hypoxia.

Hypoxia-inducible factor (HIF)-1alpha is a key regulator of anaerobic energy metabolism. We asked the following question: Does the breakdown of microtubular structures influence glycolysis in hypoxic cardiomyocytes by regulating HIF-1alpha? Neonatal rat cardiomyocytes were cultured under hypoxic conditions, while microtubule-stabilizing (paclitaxel) and -depolymerizing (colchicine) agents were used to change microtubular structure. Models of high microtubule-associated protein 4 (MAP4) expression and RNA interference of microtubulin expression were established.

The phosphatidylinositol 3-kinase-Akt pathway protects cardiomyocytes from ischaemic and hypoxic apoptosis via mitochondrial function.

1. After a severe burn, a marked decrease in myocardial blood flow results in ischaemic and hypoxic injury, which subsequently leads to apoptosis or necrosis. Phosphatidylinositol 3-kinase (PI3-K)/Akt is an important intracellular signal transduction molecule that regulates cell proliferation, differentiation, glucose metabolism and migration.

The p38/MAPK pathway regulates microtubule polymerization through phosphorylation of MAP4 and Op18 in hypoxic cells.

In both cardiomyocytes and HeLa cells, hypoxia (1% O(2)) quickly leads to microtubule disruption, but little is known about how microtubule dynamics change during the early stages of hypoxia. We demonstrate that microtubule associated protein 4 (MAP4) phosphorylation increases while oncoprotein 18/stathmin (Op18) phosphorylation decreases after hypoxia, but their protein levels do not change. p38/MAPK activity increases quickly after hypoxia concomitant with MAP4 phosphorylation, and the activated p38/MAPK signaling leads to MAP4 phosphorylation and to Op18 dephosphorylation, both of which induce microtubule disruption.

[Protective effects of enalaprilat on the myocardial kinetics in rats at early stage of severe scald].

Objective: To investigate the therapeutic effects of Enalaprilat on the myocardial kinetics in rats at early stage of severe scald.

Methods: Eighty-four SD rats were inflicted with 30% TBSA full-thickness scald, and randomly divided into scald (S, with intraperitoneal injection of isotonic saline according to Parkland formula, n=30), L (n=30), M (n=12) and H (n=12) groups. The rats in L,M,H groups were intraperitoneally injected with 1,2,4 mg/kg Enalaprilat.

[Effects of glycine on apoptosis in murine cardiomyocyte suffering from ischemia and hypoxia].

Objective: To investigate the effects of glycine on apoptosis in murine cardiomyocyte suffering from ischemia and hypoxia.

Methods: The primary passage of cultured cardiomyocytes from neonatal rats were subjected to ischemia and hypoxia, and the cells were divided into IH (without other treatment), and G (with treatment of 5 mmol/L glycine) groups. Normal murine cardiomyocytes served as control (C group).

[The influence of microtubule intervention drugs on glycolytic key enzymes in myocardial cells after hypoxia].

Objective: To investigate the influence of microtubule intervention drugs on glycolytic key enzymes in myocardial cells after hypoxia.

Methods: The primary passage of cultured myocardial cells from neonatal rats were divided into A group (with hypoxia), B group (with hypoxia and administration of l0 micromol/L colchicine), C group (with hypoxia and administration of 5 micromol/L taxol), D group (with hypoxia and administration of 10 micromol/L taxol), E group (with hypoxia and administration of 15 micromol/L taxol). The morphology of microtubule was observed with laser scanning microscope (LSM).

[Protective effects of administration of enalapril maleate on rat myocardial damage in early stage of burns].

Objective: To investigate the preventive and therapeutic effects of enalapril maleate (Enalaprilat) (E) on myocardial damage in early stage after burns.

Methods: A total of 60 SD rats were subjected to 30% TBSA III degree scald injury, and randomly divided into scald group (with conventional fluid transfusion after scald) and ENA group (with intraperitoneal injection of 1 mg/kg Enalaprilat after scald). Normal control consisted of 6 rats.

[The influence of microtubule intervention drugs on the energy metabolism of myocardial cells after hypoxia].

Objective: To investigate the influence of microtubule intervention drugs on the energy metabolism of myocardial cells after hypoxia.

Methods: The primary passage of cultured myocardial cells from neonatal rats were divided into A (with hypoxia), B (with hypoxia and administration of 10 micromol/ml colchicine), C (with hypoxia and administration of 5 micromol/ml taxol), D (with hypoxia and administration of 10 micromol/ml taxol) and E (with hypoxia and administration of 15 micromol/ml taxol) groups. The creatine kinase (CK) activity and contents of ATP and ADP were assayed with colorimetry and HPLC, respectively, and the vitality of myocardial cells were determined by trypan blue method at 0.

[Role of p38 mitogen activated protein kinase in the regulation of membrane myocardiac phospholipids degradation in early stage of severe burn rat].

Objective: To investigate the role of p38 mitogen activated protein kinase ( p38 MAPK) in the regulation of cytosolic phospholipase A2 ( cPLA2 ) expression and degradation of membrane phospholipids in myocardium in early stage of burn rats.

Methods: Wistar rats were randomized into normal group (n = 8), burn(n =40) , burn and SB203580(n = 16), burn and isotonic saline( n = 16) groups, with 8 rats at each time-points. There were 5 time-points in burn group, and 2 time-points in other groups.

[Clinical research of the effect of shengmai injection on the management of "shock heart " after burns].

Objective: To investigate the effect of Shengmai injection on the management of "shock heart" after burns.

Methods: Twenty patients with severe burns were enrolled in the study and randomly divided into two groups according to the clinical research method, i.e.

[Study on the influence of hypoxia induced microtubule damage on the opening of mitochondrial permeable transition pore of cardiac myocytes in rat].

Objective: To investigate the influence of hypoxia induced microtubule damage on the opening of mitochondrial permeable transition pore (MPTP)of cardiac myocytes and on the decrease of respiratory function in rat.

Methods: Primary cultured myocardial cells from 30 neonatal rats were randomized as normoxic group (A), hypoxia group (B), normoxia with microtubule destabilizing agent group (C, with treatment of 8 micromol/L colchicines for 30 minutes before normoxia), and hypoxia with microtubule stabilizing agent group (D, with treatment of 10 micromol/L taxol for 30 minutes before hypoxia). beta-tubulin immunofluorescence ,the opening of mitochondria permeability transition pore, and the mitochondrial inner membrane potential were detected at 0.

[Study on the mechanism of alleviation of myocardial injury after early escharectomy en masse of several burns in rat].

Objective: To investigate the alleviation of myocardial injury of rats after early escharectomy en masse of severe burns, and to explore its molecular mechanism.

Methods: Totally 66 SD rats were randomly divided into normal control (n=6), non-escharectomy (NE, n=30) and escharectomy (E, n=30, with total escharectomy 20 minutes after burns ) groups. The rats in the NE and E groups were inflicted with 30% TBSA full-thickness scald.

[An experimental study on the influence of hypoxia induction factor-1alpha on the glycolysis of the rat myocardial cell under hypoxic condition].

Objective: To investigate the influence of hypoxia induction factor-1alpha (HIF-1alpha) on glycosis of rat myocardial cell under hypoxic condition.

Methods: The myocardial cells of the rats were routinely isolated and cultured. The cells were divided into single hypoxia (H) and HIF-1alpha inhibiting (I) groups.

[Protective effect of glycine on hypoxic rat myocardial cells].

Objective: To investigate the protective effect of glycine (Gly) on hypoxic rat myocardial cells and its mechanism.

Methods: Sdfetal rat myocardial cells were isolated and cultured in vitro. The released amounts of creatine kinase (CK) and lactate dehydrogenase (LDH) from the myocardial cells in the culture supernatant at 6 hour after hypoxia and after glycine treatment were determined with ultraviolet spectrophotometer.

[Inhibition of the expression of cardiomyocytic hypoxic induction factor-1alpha during hypoxic state by double chain siRNA].

Objective: To construct hypoxic induction factor-1alpha (HIF-1alpha) siRNA expression cassette containing U6 promoter, alpha HIF-1alpha sense or antisense target sequence, and to observe its influence on the expression of cardiomyocytic HIF-1alpha during hypoxic state.

Methods: Neonatal murine cardiomyocytes cultured in the mixed gas were employed as the hypoxic model and were divided into normal control (cultured in normal oxygen), RNAi control (invalidated transfection interference sequence IV) and RNAi effective inhibition (effective transfection interference sequence, which was further divided into I, II and III groups according to the difference of downstream primer) groups. Three pairs (I, II and III) of PCR downstream primer containing HIF-1alpha encoded gene fragments (sense and antisense) and one pair of randomize sequence (IV) PCR downstream primer were designed and synthesized.

[Studies on the changes in expression of hypoxia induction factor-1alpha in myocardial tissue in severely scalded rats during early postburn stage].

Objective: To investigate the changes in the expression of hypoxia induction factor-1alpha (HIF1-alpha) in myocardial tissues in severely scalded rats during early postburn stage.

Methods: Male Wistar rats inflicted with 40% TBSA III degree scald were employed as the model. The myocardial tissue samples were harvested from the left and right ventricles at different postburn time points, and samples were also obtained from normal rats as control.