Influence of microtubule depolymerization of myocardial cells on mitochondria distribution and energy metabolism in adult rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of microtubule depolymerization of myocardial cells on distribution and activity of mitochondria, and energy metabolism of cells in adult rats.</p><p><b>METHODS</b>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. (1) The expression of polymerized beta tubulin in myocardial cells of adult and suckling rats was detected with Western blot. (2) Myocardial cells of rats in AC and AMDA groups were collected. The expression of cytochrome c was detected with Western blot. Distribution of voltage-dependent anion channels (VDAC) and polymerized beta tubulin in myocardial cells were observed with immunofluorescent staining. Mitochondrial inner membrane potential was determined with immunocytochemical method. Activity of myocardial cells was detected with MTT method. Contents of ATP, adenosine diphosphate (ADP), and adenosine monophosphate (AMP) and energy charge of cells were determined with high performance liquid chromatography.</p><p><b>RESULTS</b>(1) The expression of polymerized beta tubulin:in AMDA group it was 0.52 + or - 0.07, which was obviously lower than that (1.25 + or - 0.12) in AC group (F = 31.002, P = 0.000); in SMDA group it was 0.76 + or - 0.12, which was significantly lower than that (1.11 + or - 0.24) in SC group (F = 31.002, P = 0.000), but was obviously higher than that in AMDA group (F = 31.002, P = 0.009). (2) The expression of cytochrome c in AC group was 0.26 + or - 0.03, which was obviously lower than that (1.55 + or - 0.13) in AMDA group (t = -24.056, P = 0.000). (3) Immunofluorescent staining result: in AC group, microtubules of myocardial cells were in linear tubiform, distributed in parallel with myocardial fiber; VDAC staining result showed that mitochondria were in granular form, distributed in the same direction as microtubules. In AMDA group, the normal distribution regularity of microtubules was destroyed, with weakened immune fluorescence intensity, microtubules structure indistinct, continuity lost, rough in appearance, and the distribution of mitochondria became disrupted. (4) Mitochondrial inner membrane potential in AC group fluorescent intensity was 1288 + or - 84, which was obviously higher than that (331 + or - 27) in AMDA group (t = 26.508, P = 0.000). (5) Cellular activity: in AC group absorbance value was 1.75 + or - 0.11, which was obviously lower than that (0.81 + or - 0.07) in AMDA group (t = 17.348, P = 0.000). (6) Energy metabolism: compared with those in AC group, content of ATP decreased, contents of ADP and AMP increased, and ATP/ADP value and energy charge decreased in AMDA group.</p><p><b>CONCLUSIONS</b>Microtubules and mitochondria distribute in the same direction in normal myocardial cells in adult rats. After microtubule depolymerization, mitochondria are arranged in disorder fashion; cytochrome c leaks from mitochondria; mitochondrial membrane potential, energy supply, and cellular activity decrease in the myocardial cells.</p>

The influence of microtubule intervention drugs on glycolytic key enzymes in myocardial cells after hypoxia / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of microtubule intervention drugs on glycolytic key enzymes in myocardial cells after hypoxia.</p><p><b>METHODS</b>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). The cell vitality was assayed by cell counting kit (CCK). The activities of hexokinase (HK), pyruvate kinase (PK), phosphofructokinase (PFK) and lactate dehydrogenase (LDH) were assayed with colorimetry.</p><p><b>RESULTS</b>In group B and E, the microtubule structure was damaged heavily, and the cell vitality was decreased significantly [The cell vitality was (89.99 +/- 3.47)% in B group and (84.56 +/- 6.61)% in E group, respectively, at 1.0 post hypoxia hour (PHH), and hoth values were obviously lower than that in A group (97.44 +/- 1.76)%, P < 0.01]. The HK, PK and PFK activities decreased obviously. The activities of HK, PK and PFK in group C were similar to those of the A group. Compared with that in other groups, the degree of damage of microtubule structure in D group was milden. The activities of HK, PK and PFK in D group during 0.5 - 6.0 PHH were significantly higher than those in A group. The activity of LDH in each group was increased after hypoxia.</p><p><b>CONCLUSION</b>Proper concentration of microtubule-stabilizing drugs can alleviate the damages to microtubule structure, and enhance the activity of glycolytic key enzymes of myocardial cells at early stage of hypoxia.</p>

Effects of glycine on apoptosis in murine cardiomyocyte suffering from ischemia and hypoxia / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effects of glycine on apoptosis in murine cardiomyocyte suffering from ischemia and hypoxia.</p><p><b>METHODS</b>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). Cardiomyocytes were cultured for 6 hours in vitro. Apoptosis, mitochondrial membrane potential and its distribution, the condition of mitochondria permeability transition pore (mPTP) were observed with expression of fluorescence intensity. The activity of caspase-3 was observed by Laser Scanning staining.</p><p><b>RESULTS</b>(1) Apoptosis: the fluorescence intensity in IH group was obviously higher than that in G and C groups (P < 0.01). (2) Mitochondrial membrane potential: the fluorescence intensity in IH group was 32 +/- 7, which was obviously lower than that in G and C groups (52 +/- 4, 73 +/- 4, respectively, P < 0.01). (3) The condition of mPTP: the intensity in IH group was 27 +/- 4, which was obviously lower than that in G and C groups (62 +/- 8, 90 +/- 7, respectively, P < 0.01). (4) The activity of caspase-3: the activity of caspase-3 in IH group was obviously higher than that in G and C groups (P < 0.01).</p><p><b>CONCLUSION</b>Glycine can inhibit apoptosis in cardiomyocytes subjected to ischemia and hypoxia,and the effect may be attributable to changes in mitochondrial membrane potential, lessening opening of mPTP, alleviation of calcium overload , and decrease in activity of caspase-3.</p>

Protective effects of enalaprilat on the myocardial kinetics in rats at early stage of severe scald / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the therapeutic effects of Enalaprilat on the myocardial kinetics in rats at early stage of severe scald.</p><p><b>METHODS</b>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. Other 6 healthy rats were enrolled into study as control (C group). The myocardial kinetic parameters including left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), +/- dp/dt max and the levels of A II in myocardium were observed at 1,3,6,12 and 24 post scald hour (PBH) in L and S groups,and at 6,12 PBH in M and H groups. The above indices in C group were also examined.</p><p><b>RESULTS</b>The levels of LVSP, LVEDP, +/- dp/dt max in C group were higher than those in other groups during 3-24 PBH (P < 0.05 or P < 0.01), while those in L,M,H groups were obviously higher than those in S group (P < 0.05 or P < 0.01). The level of +/- dp/dt max in H group at 6,12 PBH were obviously lower than those in L and M groups. The level of A II in S group at 1 PBH was (53.0 +/- 2.6) pg/200 mg, which was significantly higher than thatin C group [(14.8 +/- 0.7) pg/200 mg, P < 0.05 or P < 0.01]; it peaked at6 PBH and lowered afterwards, and they were significantly higher than that in C group at 24 PBH (P < 0.01). The levels of A II in L group during 3-24 PBH were obviously higher than those in C group (P < 0.01), which were also lower than those in S group. The level of A II in S group was significantly higher than in L,M,H groups at 6 PBH [(145.2 +/- 14.5) pg/200 mg. vs. (65.1 +/- 0.9) pg/200 mg, (53.6 +/- 1.1) pg/200 mg, (34.2 +/- 0.9) pg/200 mg, respectively, P < 0.01].</p><p><b>CONCLUSION</b>Myocardium can be obviously damaged at early stage after severe scald,cardiac function is impaired. Enalaprilat injection (especially at low dose) can significantly ameliorate the myocardial kinetics indices, and it seems to exert a protective effect on cardiac function.</p>

Role of p38 mitogen activated protein kinase in the regulation of membrane myocardiac phospholipids degradation in early stage of severe burn rat / 中华烧伤杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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. The rats in the latter 3 groups were inflicted with 40% TBSA full-thickness burns, and those in burn and SB203580, burn and isotonic saline groups were administered with SB203580 (p38 MAPK inhibitor) or isotonic saline, respectively. The levels of cPLA2 mRNA and membrane phospholipids in myocardium were detected with RT-PCR. In the same experiment, the effect of SB203580 on cPLA2 expression in rat myocardial cells was determined after hypoxia and burn serum treatment in vitro.</p><p><b>RESULTS</b>The level of myocardial cPLA2 mRNA in burn group at each time-point was obviously higher than those in normal group (0. 280 +/- 0. 020) , and it reached the peak value at 3 PBH. In contrast, the level of cardiac membrane phospholipids was lowered immediately after burns, and it reached the lowest level at 6 PBH [(0. 052 +/- 0. 017) mg phosphorus/mg protein]. Herein, a significant negative correlation was showed between the levels of cPLA2 mRNA and cardiac membrane phospholipids ( r = - 0. 53, P < 0. 05). Administration of SB203580, however, inhibited the increased activity of p38 MAP kinase, suppressed the upregulation of cPLA2(72% and 51% of those in burn and saline group, P <0. 01) , and markedly increased the levels of membrane phospholipids in myocardium at 6 and 12 PBH. In addition, treatment of cardiac myocytes with SB203580 also abolished the upregulation of cPLA2 mRNA elicited by hypoxia and burn serum challenge.</p><p><b>CONCLUSION</b>p38 MAP kinase play an important role in the burn-induced degradation of cardiac membrane phospholipids in rat through the upregulation of myocardial expression of cPLA2 mRNA in the myocardial cells.</p>

The influence of microtubule intervention drugs on the energy metabolism of myocardial cells after hypoxia / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of microtubule intervention drugs on the energy metabolism of myocardial cells after hypoxia.</p><p><b>METHODS</b>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 0.5, 1.0, 3.0, 6.0, 12.0, 24.0 post-hypoxia hours (PHH).</p><p><b>RESULTS</b>The mortality was obviously higher in B and E groups than those in A group( P < 0.05) at each time-points, but that in C and D groups were markedly lower than those in A group during 6.0 to 24.0 PHH (P < 0.01). The CK activity was significantly higher in B group than that in A group during 1.0 to 24.0 PHH, while that in E group was evidently higher, but it was lower in C and D groups than that in A group at each time-points (P < 0.05 or 0.01). The ATP contents in C group during 0.5 to 6.0 PHH were [(49.9 +/- 2.8), (40.7 +/- 2.0), (25.8 +/- 1.9), (19.1 +/- 1.2) microg/10(6) cells, respectively], which were obviously higher than those in A group [(42.9 +/- 5.8), (29.5 +/- 1.8), (18.2 +/- 0.9), (14.1 +/- 0.7) microg/10(6) cells, respectively, P < 0.05 or P < 0.01, and those in E group at each time-point were significantly lower than those in A and D groups (P < 0.01). The changes in the contents of ADP were on the contrary to the above.</p><p><b>CONCLUSION</b>Microtubule-destabilizing drugs and high concentration microtubule-stabilizing drugs can sharply decrease ATP content in myocardiocytes under hypoxic conditions, while suitable amount of microtubule-stabilizing drugs can protect myocardiocytes by promoting its energy production.</p>

Influence of human C-type natriuretic peptide on vascular endothelial cell proliferation / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of human C-type natriuretic peptide (hCNP) on proliferation of vascular endothelial cells (HUVECs).</p><p><b>METHODS</b>Reconstructed pcDNA3.1 (+)/hCNP was transfected into HUVECs with polyethylenimine and its plasmid expression was examined with RT-PCR, immunohistochemistry and Western blot. MTT method was used to determine the effect of expressed protein on proliferation of HUVECs. pcDNA3.1 (+)/hCNP transfection was used for control.</p><p><b>RESULTS</b>The proliferation of HUVEC 48 h after pcDNA3.1 (+)/hCNP transfection was (0.301 +/- 0.096), which was obviously higher than that with pcDNA3.1 (+) transfection (0.164 +/- 0.012). Reconstructed pcDNA3.1 (+)/hCNP might be expressed in HUVECs effectively and its protein expression was capable of promoting HUVECs proliferation markedly.</p><p><b>CONCLUSION</b>The successive expression of reconstructed pcDNA3.1 (+)/hCNP and the promoting activity of its expressed protein on HUVECs lay the foundation potential therapeutic value of C-type natriuretic peptide.</p>

Protective effects of administration of enalapril maleate on rat myocardial damage in early stage of burns / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the preventive and therapeutic effects of enalapril maleate (Enalaprilat) (E) on myocardial damage in early stage after burns.</p><p><b>METHODS</b>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. Plasma levels of cTnI and CK-MB were determined in all the groups at 1, 3, 6, 12, 24 post-scald hours (PSH) by enzyme linked immunosorbent assay. The pathological changes in myocardium were observed at the same time-points.</p><p><b>RESULTS</b>(1) The serum level of cTnI and CK-MB in scald group were significantly higher than that of normal controls at each time-point (P < 0.01). The serum level of cTnI and CK-MB in ENA group were (1.32 +/- 0.12 microg/L to 2.47 +/- 0.22 microg/L) and (438 +/- 68 U/L to 5569 +/- 322 U/L), respectively, which were obviously lower than those in B group (6.42 +/- 0.96 microg/L to 15.10 +/- 3.69 microg/L) and (2556 +/- 74 U/L to 8047 +/- 574 U/L, P < 0.05 or P < 0.01) at different time-points. (2) Compared with normal controls, cloudy swelling, stromal blood vessel dilatation and congestion inflammatory cell infiltration were observed in scald group, but these pathological changes were less marked in ENA group.</p><p><b>CONCLUSION</b>Severe myocardial damage in rat occurred early after burns. Enalaprilat injection can markedly alleviate myocardial damage.</p>

Study on the mechanism of alleviation of myocardial injury after early escharectomy en masse of several burns in rat / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the alleviation of myocardial injury of rats after early escharectomy en masse of severe burns, and to explore its molecular mechanism.</p><p><b>METHODS</b>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. The content of ATP in mitochondria, troponin I (Tn I) in serum and 4.8-kb deletion of myocardial mitochondrial DNA (mtDNA) of the rats in each group were determined at 1, 3, 6, 12 and 24 post-scald hours (PSH).</p><p><b>RESULTS</b>(1) The content of ATP in myocardial mitochondria was decreased in both E and NE groups, but it was obviously increased at 1 and 6 PSH (0.90 +/- 0.27 microg/mg 0.66 +/- 0.19 microg/mg) in E group when compared with those in NE group (0.74 +/- 0.18 microg/mg, 0.46 +/- 0.21 microg/mg, P < 0.05). (2) There was no obvious change in the serum content of Tn I in E group at 1 and 3 PSH, but the respective content in 1, 3 and 6 PSH was markedly lower than those in NE group (P < 0.05). (3) The 4.8 kb deletion of myocardial mtDNA was found at 1, 3, 24 PSH in NE group, while it was observed only at 1, 12 PSH in E group. The partial and whole deletion rate in E group was lower than that in NE group.</p><p><b>CONCLUSION</b>Early escharectomy en masse can significantly alleviate the myocardial injury after burns,which might be related to its effect in lowering the deletion rate of myocardial mtDNA at early postburn stage.</p>

Study on the influence of hypoxia induced microtubule damage on the opening of mitochondrial permeable transition pore of cardiac myocytes in rat / 中华烧伤杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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 0.5, 1, 3, 6 and 12 post-treatment hours (PTH), and the mitochondrial respiratory function was determined by MTT method. The changes in these indices were also determined in A group at the corresponding time-points.</p><p><b>RESULTS</b>Obvious damage of polymerized microtubule, opening of MPTP, mitochondrial inner membrane potential loss and decrease of myocardial respiratory activity were observed in both group B and C at 0.5 PTH, and they became more and more serious afterwards. However, the changes in the above indices in D group were much better than those in B group (P < 0.05 or 0.01), and no difference was found between D (92.8 +/- 4.0)% and C [(100.0 +/- 0.0) %, P > 0.05] groups.</p><p><b>CONCLUSION</b>Hypoxia played a role in the myocardial microtubule damage as well as in the opening of MPTP. Moreover, hypoxia could also impair the mitochondrial respiratory function. Microtubule destabilizing agent could reproduce well the process of hypoxia induced microtubule damage, while the stabilizing agent exerted protective effect by improving the transition of mitochondrial permeability and the mitochondria respiratory function.</p>

Clinical research of the effect of shengmai injection on the management of "shock heart " after burns / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the effect of Shengmai injection on the management of "shock heart" after burns.</p><p><b>METHODS</b>Twenty patients with severe burns were enrolled in the study and randomly divided into two groups according to the clinical research method, i.e. treatment group (n= 10, with intravenous infusion of 40 ml Shengmai injection together with 250ml 50 g/L glucose solution for 3 days, 1 time/ per day) and control group(n = 10, with intravenous infusion of 290 ml 50 g/L glucose injection liquid for 3 days, 1 time/per day). Beside the venous line used for routine fluid resuscitation for burn shock, another venous line was set up after hospitalization for the administration of the drug. Blood samples were obtained from the femoral vein in both groups at 12 post-burn hour( PBH) , and on 1, 2, 3, 4 and 5 post burn days (PBD) for the determination of serum contents of creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). The changes in hepatic and renal function, as well as coagulability were determined before drug infusion and on 1 , 2, 3, 5 and 7 PSDs.</p><p><b>RESULTS</b>The serum content of CK-MB, LDH and cTnI reached the peak at 12 PBH in both groups[ (52+/-20)U/L, (5.9+/-1.3) micromol x s(-1) L(-1), (0. 274+/-0. 231) microg/L in treatment group and [(9+/-31)U/L, (8.5+/-1l.8) micromol x s(-1) x L(-1) , (0. 584+/-0. 192) microg/L in control group]. All of them decreased with the passage of time, but in the treatment group they decreased more markedly within 2 or 3 PBD compared with those in control group ( P < 0.05).</p><p><b>CONCLUSION</b>Early administration of Shengmai intravenously is beneficial to the protection of myocardial cells and in the management of the "shock heart" damage.</p>

Protective effect of glycine on hypoxic rat myocardial cells / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the protective effect of glycine (Gly) on hypoxic rat myocardial cells and its mechanism.</p><p><b>METHODS</b>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. The expression of the alpha1 subunits of glycine receptor (GlyRalpha1) in the myocardial cells was detected by immunofluorescent histochemistry. The changes in the intracellular calcium content and the membrane potential of the myocardial cells were determined by laser confocal microscopy.</p><p><b>RESULTS</b>The release of CK and LDH in the culture supernatant increased significantly at 6 h after hypoxia [(393.8 +/- 5.3), (1564 +/- 41) U/L] compared with those before hypoxia, while their levels were obviously decreased after glycine treatment [(56.3 +/- 2.7), (716 +/- 18) U/L, (P <0.01)] compared with those before glycine treatment. There was positive expression of GlyRalpha1 in myocardial cells before and after hypoxia. The average fluorescent intensity of intracellular calcium at 6 hours after hypoxia (139 +/- 29) was significantly higher than that before hypoxia (27 +/- 8, P < 0.01), while it was obviously lower (51 +/- 11) after glycine treatment compared with that at 6 hours after hypoxia,but it was evidently higher than that before hypoxia (P <0.01). The membrane potential 6 hours after hypoxia (62 +/- 9) was obviously lower than that before hypoxia (177 +/- 20, P < 0.01), but it was obviously higher after glycine treatment (123 +/- 16) than that at 6 hours after hypoxia (P < 0.01).</p><p><b>CONCLUSION</b>Glycine might be beneficial in the protection of myocardial cells against hypoxia. The underlying mechanism may involve attenuation of membrane potential depolarization after hypoxia by conjugation of glycine with its receptor, depleting in turn voltage-dependent calcium channel on the cellular membrane, preventing calcium overload due to influx of calcium ions after hypoxia.</p>

An experimental study on the influence of hypoxia induction factor-1alpha on the glycolysis of the rat myocardial cell under hypoxic condition / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the influence of hypoxia induction factor-1alpha (HIF-1alpha) on glycosis of rat myocardial cell under hypoxic condition.</p><p><b>METHODS</b>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. The cells in H group were cultured in glucose-free medium with mixed low-oxygen gas [1% O2, 94% N2 and 5% CO2 (v/v)]. While the cells in I group were cultured with low-oxygen gas after the cell model of low expression of HIF-1alpha protein constructed by RNAi technique. The cells in both groups were all observed before hypoxia (routine culture) and at the time points of 1, 3, 6, 12 and 24 hours of hypoxia. The LA (lactate acid ) content in the supernatant of the culture and the activity of the key enzymes in glycolysis such as hexokinase (HK), phosphofructokinase (PFK) and lactate dehydrogenase (LDH) of both groups of cells were determined at all the time points.</p><p><b>RESULTS</b>(1) After hypoxia, the HK and PFK activities of the rat myocardial cells in H and I groups were obviously increased at the beginning and decreased thereafter when compared with that before hypoxia. While the activities of HK and PFK in H group at 1, 3 and 6 hours after hypoxia were evidently higher than those in I group (P <0.05 or 0.01), and the peak activity of them in H and I groups was 159 +/- 13 U/g vs 133 +/- 55 U/g, and 298 +/- 44 U/g vs 188 +/- 55 U/g, respectively. (2) Compared with normal control (92 +/- 12 U/g), the LDH activity of the cells in H group after hypoxia increased significantly, reaching the peak at 6 hours after hypoxia (2 568 +/- 125 U/g, P < 0. 01), and it decreased thereafter, while that in I group peaked at 3 hours after hypoxia (2125 +/- 126 U/g, P <0.01). The LA content in the culture supernatant in H group increased significantly after hypoxia with the passage of time, while that in I group increased in smaller magnitude (P <0.01).</p><p><b>CONCLUSION</b>High expression of HIF-1alpha in the rat myocardial cells after hypoxia could directly cause continuous enhancement of cell glycolysis, which was beneficial to the protection of myocardial cells under hypoxic condition.</p>

Inhibition of the expression of cardiomyocytic hypoxic induction factor-1alpha during hypoxic state by double chain siRNA / 中华烧伤杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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. U6 starter expression frame was constructed by PCR method. The cardiomyocytes were transfected simultaneously by sense and antisense sequence expression frame. Five plates of the cells were set at each time points in each group. The expression of HIF-1alpha mRNA was detected by RT-PCR at 6 hours of hypoxia. The change in the protein expression level at 1 hour of hypoxia was determined by Western blot, and the interference effects were monitored by immunohistochemistry.</p><p><b>RESULTS</b>The best inhibition fragment screened was group II sequence. After the transfection and hypoxic culture, it was found that the cardiomyocytic HIF1alpha mRNA and protein levels in RNAi effective inhibition group were evidently lower than those in normal control and RNAi control groups (P < 0.01). While the protein inhibition rate (60% - 80%) between the former group and normal and RNAi control groups was no difference (P > 0.05).</p><p><b>CONCLUSION</b>The expression of the HIF1alpha in hypoxic rat cardiomyocytes could be effectively inhibited by our constructed HIF1alpha siRNA expression cassette group II.</p>

Studies on the changes in expression of hypoxia induction factor-1alpha in myocardial tissue in severely scalded rats during early postburn stage / 中华烧伤杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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. The mRNA and protein expressions of HIF-1alpha in rat myocardial tissue were determined by RT-PCR and Western blot analysis respectively.</p><p><b>RESULTS</b>There was a difference of HIF-1alpha expression between left and right ventricles of the normal rats at both transcriptional and translational levels, and the mRNA and protein expressions of HIF-1alpha in the myocardial tissue of scalded rats were increased dramatically at early postburn stage.</p><p><b>CONCLUSION</b>The tolerance to ischemia and hypoxia of the rat left ventricle was higher than that of the right ventricle under normal condition. An increase in HIF1alpha expression in rat myocardial tissue could be induced in severely scalded rats.</p>