Search

Cardiac alternans closely linked to calcium dysregulation is a crucial risk factor for fatal arrhythmia causing especially sudden death. Calcium overload is well-known to activate Ca

Hepatoprotective agents could prevent tissue damage and reduce morbidity and mortality rates; such agents may include folkloric or alternative treatments. The present study evaluated the protective effects of the flavonoid-rich fraction from rhizomes of Smilax glabra Roxb. (SGF) on carbon tetrachloride (CCl₄)-induced hepatotoxicity in rats. Sprague-Dawley male rats were orally treated with SGF daily and received CCl₄ intraperitoneally twice a week for 4 weeks. Our results showed that SGF at doses of 100, 300 and 500 mg/kg significantly reduced the elevated activities of serum aminotransferases (ALT and AST), alkaline phosphatase and lactate dehydrogenase and the level of hepatic thiobarbituric acid-reactive substances compared to the CCl₄-treated group. Moreover, SGF treatment was also found to significantly increase the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and glutathione compared with CCl₄-induced intoxicated liver. Histopathologic examination revealed that CCl₄-induced hepatic damage was markedly reversed by SGF. The results suggest that SGF has hepatoprotective and antioxidant properties in CCl₄-induced liver injury in rats.

The article evaluated the inhibitory action of procaine on wild-type and mutated HERG potassium channel current (IHERG) to determine whether mutations in the S6 region are important for the inhibition of IHERG by procaine. HERG channels (WT, Y652A, and F656A) were expressed in Xenopus laevis oocytes and studied using the standard two-microelectrode voltage-clamp technique. The results revealed that WT HERG is blocked in a concentration-, voltage-, and state-dependent manner by procaine ([IC50] = 34.79 μM). The steady state activation curves slightly move to the negative, while inactivation parameters move to the positive in the presence of procaine. Time-dependent test reveals that voltage-dependent IHERG blockade occurs extremely rapidly. Furthermore, the mutation to Ala of Y652 and F656 produce about 11-fold and 18-fold increases in IC50 for IHERG blockade, respectively. Simultaneously, for Y652A, the steady state activation and inactivation parameters are shifted to more positive values after perfusion of procaine. Conclusively, procaine state-dependently inhibits HERG channels (WT, Y652A, and F656A). The helix residues Y652 and F656 in the S6 transmembrane domain might play a role in interaction of the drug with the channel. Keywords:: procaine, inhibition, HERG channel, mutation, voltage clamp

Autografts have been extensively studied to facilitate optic nerve (ON) regeneration in animal experiments, but the clinical application of this approach to aid autoregeneration has not yet been attempted. This study aims to explore the guided regeneration by an artificial polyglycolic acid-chitosan conduit coated with recombinant L1-Fc. Consistent with previous studies; in vitro assay showed that both chitosan, a natural biomaterial, and the neural cell adhesion molecule L1-Fc enhanced neurite outgrowth. Rat optic nerve transection was used as an in vivo model. The implanted PGA-chitosan conduit was progressively degraded and absorbed, accompanied by significant axonal regeneration as revealed by immunohistochemistry, anterograde and retrograde tracing. The polyglycolic acid-chitosan conduit coated with L1-Fc showed more effective to promote axonal regeneration and remyelination. Taken together, our observations demonstrated that the L1-Fc coated PGA-chitosan conduits provided a compatible and supportive canal to guild the injured nerve regeneration and remyelination.

Ranolazine (RAN), a novel antianginal agent, inhibits the increased late sodium current (INa.L) under many pathological conditions. In this study, the whole-cell patch-clamp technique was used to explore the effects of RAN on INa.L and reverse Na(+)/Ca(2+) exchange current (INCX) in rabbit ventricular myocytes during hypoxia.Tetrodotoxin (TTX) at 2 μM or RAN at 9 μM decreased significantly INa.L and reverse INCX under normoxia and RAN had no further effects on both currents in the presence of TTX. RAN (3, 6, and 9 μM) attenuated hypoxia-increased INa.L and reverse INCX in a concentration-dependent manner. Hypoxia-increased INa.L and reverse INCX were inhibited by 2 μM TTX, whereas 9 μM RAN applied sequentially did not further decrease both currents. In another group, after both currents were decreased by 9 μM RAN, 2 μM TTX had no further effects in the presence of Ran. In monophasic action potential (MAP) recording, early after-depolarizations (EADs) were suppressed by RAN (9 μM) during hypoxia. In conclusion, RAN decreased reverse INCX by inhibiting INa.L in normoxia, concentration-dependently attenuated the increase of INa.L, which thereby decreased the reverse INCX, and obviously relieved EADs during hypoxia.

The protective effects of puerarin on liver damage were evaluated by carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. Male rats were orally treated with puerarin daily, and received CCl4 intraperitoneally twice a week for 4 weeks. Our results showed that puerarin at doses of 50, 100, and 200 mg/kg b.w. significantly reduced the elevated activities of serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase at least 15%, 17%, 14% and 18%, respectively. In addition, puerarin at different doses significantly decreased (p < 0.05) the level of hepatic thiobarbituric acid reactive substances compared to the CCl4-treated group. Furthermore, the treatment of puerarin was also found to significantly increase the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and glutathione content at least 40%, 12%, 25%, 52%, 17% and 44% in the liver of CCl4-treated rats, respectively. Liver histopathology also showed that puerarin reduced the incidence of liver lesions induced by CCl4. The results suggest that puerarin exhibits potent hepatoprotective effects on CCl4-induced liver damages in rats, and that the hepatoprotective effects of puerarin may be due to both the inhibition of lipid peroxidation and to increase of antioxidant enzymes activity.

To investigate the effect of hypoxia/early reoxygenation on persistent sodium current (I(Na.P)) in single ventricular myocytes of guinea pig and discuss its role and significance during this pathological condition.The whole cell patch clamp technology was used to record this current and study its change under the condition of hypoxia/reoxygenation model.(1) With 0.5 Hz, 1 Hz and 2 Hz pulse frequency, the current density gap between the first and the eighth pulse of I(Na.P) was (0.021 +/- 0.014) pA/ pF, (0.097 +/- 0.014) pA/pF and (0.133 +/- 0.024) pA/pF (P0.01) respectively. (2) Depolarization with membrane holding potential of -150 - -80 mV respectively, I(Na.P) density attenuated gradually. (3) The amplitude of I(Na.P) was increased consistently with the prolongation of hypoxia time during hypoxia. (4) I(Na.P) was (0.500 +/- 0.125) pA/pF, (1.294 +/- 0.321) pA/pF and (0.988 +/- 0.189) pA/pF (P0.01, vs normoxia, respectively) during normoxia, hypoxia after 15 min and reoxygenation after 5 min, respectively.These results indicate that I(Na.P) has great significance in arrhythmogenesis and calcium-overload, which causes the following postischemia and post hypoxia myocardial damage.

A variety of nerve conduits incorporated with chemical and biological factors have been developed to further stimulate nerve regeneration. Although most of the nerve guides in studies are basically limited to bridge a short gap of nerve defect in rat models, it is vital to evaluate effects of conduits on nerve regeneration over distance greater than 20 mm, or more clinically relevant nerve gap lengths in higher mammals. In this study, a poly(lactide-co-glycolide) (PLGA) nerve conduit, treated with pulsed plasma and coated with ciliary neurotrophic factor (CNTF) as well as chitosan, was used to repair 25-mm-long canine tibial nerve defects in eighteen cross-bred dogs. The canines were randomly divided into three groups (n = 6), a 25-mm segment of the tibial nerve was removed and replaced by a PLGA/chitosan-CNTF nerve conduit, PLGA/chitoson conduit and autologous nerve grafts were performed as the control. The results were evaluated by general observation, eletromyogram testing, S-100 histological immunostaining, and image analysis at 3 months after operation. The histological results demonstrated that the PLGA/chitosan-CNTF conduits and PLGA/chitosan conduits were capable of leading the damaged axons through the lesioned area. Through the comparation of the three groups, the results in PLGA/chitosan-CNTF conduits group were better than that of PLGA/chitosan conduits group, while they were similar to autologous nerve grafts group. Therefore, CNTF-coated PLGA/chitosan nerve conduits could be an alternative artificial nerve conduit for nerve regeneration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.

Whole-cell and cell-attached patch-clamp techniques were used to record the changes of persistent sodium current (I(Na.P)) in ventricular myocytes of guinea pig to investigate the effect of low extracellular pH on I(Na.P) and its mechanism. The results showed that low extracellular pH (7.0, 6.8 and 6.5) obviously increased the amplitude of whole-cell I(Na.P) in a [H(+)] concentration-dependent manner. Under the condition of extracellular pH 6.5, I(Na.P) was markedly augmented from control (pH 7.4) value of (0.347+/-0.067) pA/pF to (0.817+/- 0.137) pA/pF (P0.01, n=6), whereas the reducing agent dithiothreitiol (DTT, 1 mmol/L) reversed the increased IN(Na.P) from (0.817+/-0.137) pA/pF to (0.233+/-0.078) pA/pF (P0.01 vs pH 6.5, n=6). Decreasing extracellular pH to 6.5 also increased the persistent sodium channel activity in cell-attached patches. The mean open probability and mean open time were increased from control value of 0.021+/-0.007 and (0.899+/-0.074) ms to 0.205+/-0.023 and (1.593+/-0.158) ms, respectively (both P0.01, n=6), and such enhancement was reversed by application of 1 mmol/L DTT [to 0.019+/-0.005 and (0.868+/-0.190) ms, both P0.01 vs pH 6.5, n=6]. Furthermore, protein kinase C (PKC) inhibitor bisindolylmaleimide (BIM, 5 micromol/L) reduced the enhanced mean open probability and mean open time at pH 6.5 from 0.214+/-0.024 and (1.634+/-0.137) ms to 0.025+/-0.006 and (0.914+/-0.070) ms, respectively (both P0.01 vs pH 6.5, n=6). The results demonstrate that low extracellular pH markedly increases I(Na.P) in guinea pig ventricular myocytes, in which activation of PKC may be involved.

Laurencia terpenoid extract (LET) had been extracted from the red alga Laurencia tristicha. The study is to investigate the effects of LET supplementation on DNA oxidation and alkylation damages in mice. Forty healthy Kunming mice weighing between 18g and 25g were randomly assigned into 4 groups, each consisting of ten animals. The mice were orally intubated respectively for 60 days with the designed concentrations of LET (25, 50,100mg/ kg b.w.) for three exposed groups and salad oil (0.2 ml) for the blank group. Food and water were free for the animals. Mice in the blank and exposed groups were sacrificed after the last treatment and the blood of each animal was quickly taken for further experiments. The spontaneous and oxidized DNA damages of peripheral lymphocytes induced by H2O2 were analysed by SCGE. O6-Methy-guanine (O6-MeG) was measured by high performance capillary zone electrophoresis. There was no significantly difference in DNA spontaneous damage on peripheral lymphocytes of all the mice. The oxidative DNA damage in the 50 mg/Kg body weight supplement group are 286AU with the oxidation of 10 micromol/L H2O2, significantly lower than the blank group 332AU (p0.05). The contents of O6-MeG in plasma in the 50 mg/kg b.w. and 100mg/kg b.w. supplement group were 1.50 micromol/L and 1.88 micromol/L, significantly lower than that of the blank group, which was 2.89 micromol/L(p0.05). The results from the present study indicated that the LET were rich in terpenoids and safety to be taken orally and it could improve antioxidative and decrease DNA damage effectively.

In this paper, membrane current properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using two-microelectrode voltage clamp technique. Axion of adult female toad was destroyed, and then ovarian lobes containing oocytes in stage I to VI were removed and incubated in Ca(2+)-free ND96 solution with collagenase (1.5 mg/ml) for 1 h. Subsequently, the oocytes were washed in Ca(2+)-free ND96 solution for 10 min to completely remove the follicular layer. For the experiments only the oocytes in stage V and VI were selected and used during 1 to 5 d. The membrane was depolarized from a holding potential of -80 mV to +60 mV in 10 mV step. It was found that a sustained outward current was elicited by depolarization. Potassium channel blockers (tetraethylammonium chloride, TEA, 10 mmol/L and 4-aminopyridine, 4-AP, 10 mmol/L) reduced the outward current to (23.4+/-0.72)% of the maximum. However, further addition of chloride channel blocker (5-nitro-2, 3-phenypropylamino benzoate, NPPB, 30 micromol/L) could almost completely block the outward current to (2.1+/-0.08)% of the maximum. In the presence of TEA and 4-AP, removal of extracellular Ca(2+) or adding verapamil (40 micromol/L), could also reduce the outward current to (2.2+/-0.04) % and (3.1+/-0.15) % of the maximum, respectively. It is concluded that calcium-dependent chloride channels exist in plasma membrane of Bufo bufo gargarizans oocytes, besides potassium channels.

To study the clinical efficacy of three kinds of hybrid bioartificial liver support systems (HBLSS) in treating chronic severe hepatitis.A bioartificial liver support system (BAL), comprising porcine hepatocytes and fiber tube style bioreactor, was constructed. Then three kinds of HBLSS were constructed: Molecular absorbent recirculating system (MARS) plus BAL; slow plasma exchange (SPE) plus continuous hemodiafiltration (CHDF) and BAL; and SPE plus hemoperfusion (HP) and BAL. One hundred-twenty patients in middle or late stages of chronic severe hepatitis were enrolled in this study. They were randomly divided into 6 groups: H1 group was treated with BAL+MARS, H2 with BAL+SPE+CHDF and H3 with BAL+SPE+HP (as treatment groups); C1 group was treated with MARS, C2 with SPE+CHDF and C3 with SPE+HP (as control groups). The changes in the clinical symptoms, in the hepatic encephalopathy stages, and in the serum total bilirubin (TBIL), the serum albumin (ALB), the prothrombin activities (PTA), endotoxin, ammonia, creatinine and a-fetal protein (AFP) were all observed before the treatment, right after it and 72 hours later. The improving and curing rates and the rates of side effect occurrences in each group were observed.In all 6 groups, the patients' clinical symptoms ameliorated; their TBIL, endotoxin and ammonia levels decreased (P0.05), and their PTA and AFP levels lowered significantly (P0.05). But in the H1, H2 and H3 groups they were more distinctive than in the control groups. In H1 and H2 groups creatinine and ammonia levels were decreased more significantly than in the H3 group (P0.05). The improving and curing rates of each group were 65 % (13/20), 60% (12/20), 45% (9/20), 45% (9/20), 40% (8/20) and 20% (4/20) respectively. No serious side effects were observed during the treatment.In treating middle and late stage chronic severe hepatitis, the measures used in H1, H2 and H3 are better than those in C1, C2 and C3. Furthermore, H1 and H2 treatments can ameliorate hepatic and renal functions, prevent the development of multiple organ dysfunction syndrome, and are better than those used in H3.

To study the effect of hydrogen peroxide (H2O2) on persistent sodium current (I(Na.P)) in guinea pig ventricular myocytes.The whole-cell, cell-attached, and inside-out patch-clamp techniques were applied on isolated ventricular myocytes from guinea pig.H2O2 (0.1 mmol/L, 0.5 mmol/L and 1.0 mmol/L) increased the amplitude of whole-cell I(Na.P) in a concentration-dependent manner, and glutathione (GSH 1 mmol/L) reversed the increased I(Na.P). H2O2 (1 mmol/L) increased persistent sodium channel activity in cell-attached and inside-out patches. The mean open probability was increased from control values of 0.015+/-0.004 and 0.012+/-0.003 to 0.106+/-0.011 and 0.136+/-0.010, respectively (P0.01 vs control). They were then decreased to 0.039+/-0.024 and 0.027+/-0.006, respectively, after the addition of 1 mmol/L GSH (P0.01 vs H2O2). The time when open probability began to increase and reached a maximum was shorter in inside-out patches than that in cell-attached patches (4.8+/-1.0 min vs 11.5+/-3.9 min, P0.01; 9.6+/-1.6 min vs 18.7+/-4.7 min, P0.01).H2O2 increased the I(Na.P) of guinea pig ventricular myocytes in a concentration-dependent manner, possibly by directly oxidating the cell membrane.

Whole cell patch-clamp technique was used to record the changes of persistent sodium current (I(Na.P)) and the effect of administered agents in ventricular myocytes of guinea pig to investigate the essence of I(Na.P) and mechanism of increased I(Na.P) of ventricular myocytes during hypoxia. The results showed: (1) Pro-NO L-arginine(L-Arg) and donor sodium nitroprusside (SNP) increased I(Na.P) in a concentration-dependent manner in normoxia. (2) I(Na.P) increased gradually with the prolongation of hypoxia time. After 15 min of hypoxia, administration of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, could not significantly recover the increased I(Na.P) [(1.344+/-0.320) vs (1.301+/-0.317) pA/pF, P0.05, n=5]; (3) During hypoxia the perfusion solution with L-NAME decreased the increased I(Na.P), and the difference was significant compared with pure hypoxia [(0.914+/-0.263), n=5 vs (1.344+/-0.320) pA/pF, P0.05, n=6], whereas the amplitude of I(Na.P) was still larger than that in normoxia [(0.914+/-0.263) vs (0.497+/-0.149) pA/pF, P0.05, n=5]; (4) Reducing agent dithiothreitiol (DTT) not only recovered the increased I(Na.P) by L-Arg and administered SNP after hypoxia [(1.449+/-0.522) vs (0.414+/-0.067) pA/pF, P0.01, n=6, and (1.786+/-0.636) vs (0.436+/-0.141) pA/pF, P0.01, n=5, respectively], but also decreased the I(Na.P) in normoxia [(0.442+/-0.056) vs (0.396+/-0.057) pA/pF, P0.01, n=6]. Our results suggest that hypoxia increases I(Na.P) of ventricular myocytes, which is induced by raised NO oxidating sodium channel protein in myocardial membrane during hypoxia. The activity of I(Na.P) in normoxia is related to the oxidation state of the channel protein.