Central cholinergic regulation of respiration： nicotinic receptors

Nicotinic acetylcholine receptors （nAChRs） are expressed in brainstem and spinal cord regions involved in the control of breathing. These receptors mediate central cholinergic regulation of respiration and effects of the exogenous ligand nicotine on respiratory pattern. Activation of α4＊ nAChRs in the preBotzinger Complex （preBotC）, an essential site for normal respiratory rhythm generation in mammals, modulates excitatory glutamatergic neurotransmission and depolarizes preBotC inspiratory neurons, leading to increases in respiratory frequency, nAChRs are also present in motor nuclei innervating respiratory muscles. Activation of post- and/or extra-synaptic α4＊ nAChRs on hypoglossal （XII） motoneurons depolarizes these neurons, potentiating tonic and respiratory-related rhythmic activity. As perinatal nicotine exposure may contribute to the pathogenesis of sudden infant death syndrome （SIDS）, we discuss the effects of perinatal nicotine exposure on development of the cholinergic and other neurotransmitter systems involved in control of breathing. Advances in understanding of the mechanisms underlying central cholinergic/nicotinic modulation of respiration provide a pharmacological basis for exploiting nAChRs as therapeutic targets for neurological disorders related to neural control of breathing such as sleep apnea and SIDS.     

Allosteric activation mechanism of the cys-loop receptors

Binding of a neurotransmitter to its ionotropic receptor opens a distantly located ion channel, a process termed allosteric activation. Here we review recent advances in the molecular mechanism by which the cys-loop receptors are activated with emphasis on the best studied nicotinic acetylcholine receptors （nAChRs）. With a combination of affinity labeling, mutagenesis, electrophysiology, kinetic modeling, electron microscopy （EM）, and crystal structure analysis, the allosteric activation mechanism is emerging. Specifically, the binding domain and gating domain are interconnected by an allosteric activation network. Agonist binding induces conformational changes, resulting in the rotation of a β sheet of aminoterminal domain and outward movement of loop 2, loop F, and cys-loop, which are coupled to the M2-M3 linker to pull the channel to open. However, there are still some controversies about the movement of the channel-lining domain M2. Nine angstrom resolution EM structure of a nAChR imaged in the open state suggests that channel opening is the result of rotation of the M2 domain. In contrast, recent crystal structures of bacterial homologues of the cys-loop receptor family in apparently open state have implied an M2 tilting model with pore dilation and quaternary twist of the whole pentameric receptor. An elegant study of the nAChR using protonation scanning of M2 domain supports a similar pore dilation activation mechanism with minimal rotation of M2. This remains to be validated with other approaches including high resolution structure determination of the mammalian cys-loop receptors in the open state.     

Addictive evaluation of cholic acid-verticinone ester,a potential cough therapeutic agent with agonist action of opioid receptor

Aim： The purpose of this work was to search for potential drugs with potent antitussive and expectorant activities as well as a low toxicity, but without addictive properties. Cholic acid-verticinone ester （CA-Ver） was synthesized based on the clearly elucidated antitussive and expectorant activities of verticinone in bulbs of Fritillaria and different bile acids in Snake Bile. In our previous study, CA-Ver showed a much more potent activity than codeine phosphate. This study was carried out to investigate the central antitussive mechanism and the addictive evaluation of CA-Ver. Methods： Testing on a capsaicin-induced cough model of mice pretreated with naloxone, a non-selective opioid receptor antagonist, was performed for the observation of CA-Ver＇s central antitussive mechanism. We then took naloxone-induced withdrawal tests of mice for the judgment of CA-Ver＇s addiction. Lastly, we determined the opioid dependence of CA-Ver in the guinea pig ileum. Results： The test on the capsaicin-induced cough model showed that naloxone could block the antitussive effect of CA-Ver, suggesting the antitussive mechanism of CA-Ver was related to the central opioid receptors. The naloxone-urged withdrawal tests of the mice showed that CA-Ver was not addictive, and the test of the opioid dependence in the guinea pig ileum showed that CA-Ver had no withdrawal response. Conclusion： These findings suggested that CA-Ver deserved attention for its potent antitussive effects related to the central opioid receptors, but without addiction, and had a good development perspective.     

Pivotal effects of phosphodiesterase inhibitors on myocyte contractility and viability in normal and ischemic hearts

Phosphodiesterases （PDEs） are enzymes that degrade cellular cAMP and cGMP and are thus essential for regulating the cyclic nucleotides. At least 11 families of PDEs have been identified, each with a distinctive structure, activity, expression, and tissue distribution. The PDE type-3, -4, and -5 （PDE3, PDE4, PDE5） are localized to specific regions of the cardiomyocyte, such as the sarcoplasmic reticulum and Z-disc, where they are likely to influence cAMP/cGMP signaling to the end effectors of contractility. Several PDE inhibitors exhibit remarkable hemodynamic and inotropic properties that may be valuable to clinical practice. In particular, PDE3 inhibitors have potent cardiotonic effects that can be used for short-term inotropic support, especially in situations where adrenergic stimulation is insufficient. Most relevant to this review, PDE inhibitors have also been found to have cytoprotective effects in the heart. For example, PDE3 inhibitors have been shown to be cardioprotective when given before ischemic attack, whereas PDE5 inhibitors, which include three widely used erectile dysfunction drugs （sildenafil, vardenafil and tadalafil）, can induce remarkable cardioprotection when administered either prior to ischemia or upon reperfusion. This article provides an overview of the current laboratory and clinical evidence, as well as the cellular mechanisms by which the inhibitors of PDE3, PDE4 and PDE5 exert their beneficial effects on normal and ischemic hearts. It seems that PDE inhibitors hold great promise as clinically applicable agents that can improve cardiac performance and cell survival under critical situations, such as ischemic heart attack, cardiopulmonary bypass surgery, and heart failure.     

Response of mesenchymal stem cells to shear stress in tissueengineered vascular grafts

Aim： Recent studies have demonstrated that mesenchymal stem cells （MSCs） can differentiate into endothelial cells. The effect of shear stress on MSC differentiation is incompletely understood, and most studies have been based on two-dimensional systems. We used a model of tissue-engineered vascular MSC differentiation. grafts （TEVGs） to investigate the effects of shear stress on Methods： MSCs were isolated from canine bone marrow. The TEVG was constructed by seeding MSCs onto poly-ε- caprolactone and lactic acid （PCLA） scaffolds and subjecting them to shear stress provided by a pulsatile bioreactor for four days （two days at 1 dyne/cm^2 to 15 dyne/cm^2 and two days at 15 dyne/cm^2）. Results： Shear stress significantly increased the expression of endothelial cell markers, such as platelet-endothelial cell adhesion molecule-1 （PECAM-1）, VE-cadherin, and CD34, at both the mRNA and protein levels as compared with static control cells. Protein levels of alpha-smooth muscle actin （α-SMA） and calponin were substantially reduced in shear stresscultured cells. There was no significant change in the expression of α-SMA, smooth muscle myosin heavy chain （SMMHC） or calponin at the mRNA level. Conclusion： Shear stress upregulated the expression of endothelial cell-related markers and downregulated smooth muscle-related markers in canine MSCs. This study may serve as a basis for further investigation of the effects of shear stress on MSC differentiation in TEVGs.     

Nicotinic acetylcholine receptor α7 subunits with a C2 cytoplasmic loop yellow fluorescent protein insertion form functional receptors

Aim： Several nicotinic acetylcholine receptor （nAChR） subunits have been engineered as fluorescent protein （FP） fusions and exploited to illuminate features of nAChRs. The aim of this work was to create a FP fusion in the nAChR α7 subunit without compromising formation of functional receptors, Methods： A gene construct was generated to introduce yellow fluorescent protein （YFP）, in frame, into the otherwise unaltered, large, second cytoplamsic loop between the third and fourth transmembrane domains of the mouse nAChR α7 subunit （α7Y）. SH-EP1 cells were transfected with mouse nAChR wild type α7 subunits （α7） or with α7Y subunits, alone or with the chaperone protein, hRIC-3. Receptor function was assessed using whole-cell current recording. Receptor expression was measured with 125I-labeled α-bungarotoxin （I-Bgt） binding, laser scanning confocal microscopy, and total internal reflectance fluorescence （TIRF） microscopy. Results： Whole-cell currents revealed that α7Y nAChRs and α7 nAChRs were functional with comparable EC50 values for the α7 nAChR-selective agonist, choline, and IC50 values for the α7 nAChR-selective antagonist, methyllycaconitine. I-Bgt binding was detected only after co-expression with hRIC-3. Confocal microscopy revealed that α7Y had primarily intracellular rather than surface expression. TIRF microscopy confirmed that little α7Y localized to the plasma membrane, typical of α7 nAChRs. Conclusion： nAChRs composed as homooligomers of α7Y subunits containing cytoplasmic loop YFP have functional, ligand binding, and trafficking characteristics similar to those of α7 nAChRs, α7Y nAChRs may be used to elucidate properties of α7 nAChRs and to identify and develop novel probes for these receptors, perhaps in high-throughput fashion.     

The impact of extracellular and intracellular Ca2＋ on ethanol-induced smooth muscle contraction

Aim： To evaluate the impact of extracellular and intracellular Ca2＋ on contractions induced by ethanol in smooth muscle. Methods： Longitudinal smooth muscle strips were prepared from the gastric fundi of mice. The contractions of smooth muscle strips were recorded with an isometric force displacement transducer. Results： Ethanol （164 mmol/L） produced reproducible contractions in isolated gastric fundal strips of mice. Although lidocaine （50 and 100 μmol/L）, a local anesthetic agent, and hexamethonium （100 and 500 μmol/L）, a ganglionic blocking agent, failed to affect these contractions, verapamil （1-50 μmol/L） and nifedipine （1-50 pmol/L）, selective blockers of L-type Ca2＋ channels, significantly inhibited the contractile responses of ethanol. Using a Ca2＋-free medium nearly eliminated these contractions in the same tissue. Ryanodine （1-50 μmol/L） and ruthenium red （10-100 pmol/L）, selective blockers of intracellular Ca2＋ channels/ryanodine receptors; cyclopiazonic acid （CPA; 1-10 μmol/L）, a selective inhibitor of sarcoplasmic reticulum （SR） Ca2＋-ATPase; and caffeine （0.5-5 mmol/L）, a depleting agent of intracellular Ca2＋ stores, significantly inhibited the contractile responses induced by ethanol. In addition, the com- bination of caffeine （5 mmol/L） plus CPA （10 μmol/L）, and ryanodine （10 μmol/L） plus CPA （10 μmol/L）, caused further inhibition of contractions in response to ethanol. This inhibition was significantly different from those associated with caffeine, ryanodine or CPA. Furthermore the combination of caffeine （5 mmol/L）, ryanodine （10 μmol/L） and CPA（IO pmol/L） eliminated the contractions induced by ethanol in isolated gastric fundal strips of mice. Conclusion： Both extracellular and intracellular Ca2＋ may have important roles in regulating contractions induced by ethanol in the mouse gastric fundus.     

The peroxisome proliferator-activated receptor-α （PPAR-α） agonist,AVE8134, attenuates the progression of heart failure and increases survival in rats

Aim： To investigate the efficacy of the peroxisome proliferator-activated receptor-α （PPARa） agonist, AVE8134, in cellular and experimental models of cardiac dysfunction and heart failure.
Methods： In Sprague Dawley rats with permanent ligation of the left coronary artery （post-MI）, AVE8134 was compared to the PPARy agonist rosiglitazone and in a second study to the ACE inhibitor ramipril. In DOCA-salt sensitive rats, efficacy of AVE8134 on cardiac hypertrophy and fibrosis was investigated. Finally, AVE8134 was administered to old spontaneously hypertensive rats （SHR） at a nonblood pressure lowering dose with survival as endpoint. In cellular models, we studied AVE8134 on hypertrophy in rat cardiomyocytes nitric oxide signaling in human endothelial cells （HUVEC） and LDL-uptake in human MonoMac-6 cells.
Results： In post-MI rats, AVE8134 dose-dependently improved cardiac output, myocardial contractility and relaxation and reduced lung and left ventricular weight and fibrosis. In contrast, rosiglitazone exacerbated cardiac dysfunction. Treatment at AVE8134 decreased plasma proBNP and arginine and increased plasma citrulline and urinary NOx/creatinine ratio. In DOCA rats, AVE8134 prevented development of high blood pressure, myocardial hypertrophy and cardiac fibrosis, and ameliorated endothelial dysfunction. Compound treatment increased cardiac protein expression and phosphorylation of eNOS. In old SHR, treatment with a low dose of AVE8134 improved cardiac and vascular function and increased life expectancy without lowering blood pressure. AVE8134 reduced phenylephrine-induced hypertrophy in adult rat cardiomyocytes. In HUVEC, Ser-1177-eNOS phosphorylation but not eNOS expression was increased. In monocytes, AVE8134 increased the expression of CD36 and the macrophage scavenger receptor 1, resulting in enhanced uptake of oxidized LDL.
Conclusion： The PPARa agonist AVE8134 prevents post-MI myocardial hypertrophy, fibrosis and cardiac dysfunction. AVE8134 has beneficial effects against hy     

Glutamate receptors in the dorsal hippocampus mediate the acquisition,but not the expression,of conditioned place aversion induced by acute morphine withdrawal in rats

Aim： To evaluate the role of glutamate receptors in the dorsal hippocampus （DH） in the motivational component of morphine withdrawal. Methods： NMDA receptor antagonist D-AP5 （5 pg/0.5 pL per side） or AMPA receptor antagonist NBQX （2 pg/0.5 pL per side） was micro- injected into DH of rats. Conditioned place aversion （CPA） induced by naloxone-precipitated morphine withdrawal were assessed. Results： Preconditioning microinjection of D-AP5 or NBQX into the DH impaired the acquisition of CPA in acute morphine-dependent rats. However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expres- sion of CPA. Conclusion： Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.     

Increase in sphingolipid catabolic enzyme activity during aging

Aim： To understand the contribution of sphingolipid metabolism and its metabolites to development and aging. Methods： A systemic analysis on the changes in activity of sphingolipid metabolic enzymes in kidney, liver and brain tissues during development and aging was conducted. The study was conducted using tissues from 1-day-old to 720-day-old rats. Results： Catabolic enzyme activities as well as the level of sphingomyelinase （SMase） and ceramidase （CDase） were higher than that of anabolic enzyme activities, sphingomyelin synthase and ceramide synthase. This suggested an accumulation of ceramide and sphingosine during development and aging. The liver showed the highest neutral-SMase activity among the tested enzymes while the kidney and brain exhibited higher neutral-SMase and ceramidase activities, indicating a high production of ceramide in liver and ceramide/sphingosine in the kidney and brain. The activities of sphingolipid metabolic enzymes were significantly elevated in all tested tissues during development and aging, although the onset of significant increase in activity varied on the tissue and enzyme type. During aging, 18 out of 21 enzyme activities were further increased on day 720 compared to day 180. Conclusion： Differential increases in sphingolipid metabolic enzyme activities suggest that sphingolipids including ceramide and sphingosine might play important and dynamic roles in proliferation, differentiation and apoptosis during development and aging.     

Functional study of the effect of phosphatase inhibitors on KCNQ4 channels expressed in Xenopus oocytes

Aim： KCNQ4 channels play an important part in adjusting the function of cochlear outer hair cells. The aim of this study was to investigate the effects of ser/thr phosphatase inhibitors on human KCNQ4 channels expressed in Xenopus laevis oocytes. Methods： Synthetic cRNA encoding human KCNQ4 channels was injected into Xenopus oocytes. We used a two-electrode voltage clamp to measure the ion currents in the oocytes. Results： Wild-type KCNQ4 expressed in Xenopus oocytes showed the typical properties of slow activation kinetics and low threshold activation. The outward K~ current was almost completely blocked by a KCNQ4 blocker, linopirdine （0.25 mmol/L）. BIMI （a PKC inhibitor） prevented the effects of PMA （a PKC activator） on the KCNQ4 current, indicating that PKC may be involved in the regulation of KCNQ4 expressed in the Xenopus oocyte system. Treatment with the ser/thr phosphatase inhibitors, cyclosporine （2 pmol/L）, calyculin A （2 pmol/L） or okadaic acid （1 pmol/L）, caused a significant positive shift in V1/2 and a decrease in the conductance of KCNQ4 channels. The V1/2 was shifted from -14.6±0.5 to -6.4±0.4 mV by cyclosporine, -18.8±0.5 to -9.2_＋0.4 mV by calyculin A, and -14.1±0.5 to -0.7＋0.6 mV by okadaic acid. Moreover, the effects of these phosphatase inhibitors （okadaic acid or calyculin A） on the induction of a positive shift of V1/2 were augmented by further addition of PMA. Conclusion： These results indicate that ser/thr phosphatase inhibitors can induce a shift to more positive potentials of the activation curve of the KCNQ4 current. It is highly likely that the phosphatase functions to balance the phosphorylated state of substrate protein and thus has an important role in the regulation of human KCNQ4 channels expressed in Xenopus oocytes.     

Natural products as promising drug candidates for the treatment of hepatitis B and C

Hepatitis B virus （HBV） or hepatitis C virus （HCV） infections are a major threat worldwide. Combination therapy of interferon-α and ribavirin is currently the treatment of choice for HCV-infected patients. However, this regimen is only effective in approximately 50% of patients and provokes severe side-effects. Numerous natural alternatives for treating HCV have been suggested. Deoxynojirimycin and its derivatives are iminosugars which exert anti-HCV activity by inhibiting α-glucosidases. A non-immunosuppressive derivate of cyclosporine A, NIM811, exerts anti-HCV activity by binding to cyclophilin. Other natural products with promising anti-HCV activity are 2-arylbenzofuran derivatives, Mellein, and pseudoguaianolides. For HBV treatment, several drugs are available, specifically targeting the virus polymerase （lamivudine, entecavir, telbivudine, and adefovir dipivoxil）. The efficacy of these drugs is hampered by the development of resistance due to point mutations in the HBV polymerase. Due to drug resistance and adverse side-effects, the search for novel drugs is mandatory. Wogonin, ellagic acid, artemisinin and artesunate, chrysophanol 8-O-β-D-glucoside, saikosaponin C, and protostane triterpenes are active against HBV. Natural products need to be investigated in more detail to explore their potential as novel adjuncts to established HBV or HCV therapy.     

Expression pattern of neural synaptic plasticity marker-Arc in different brain regions induced by conditioned drug withdrawal from acute morphine-dependent rats

Aim： The immediate early gene Arc （activity-regulated cytoskeletal-associated protein） mRNA and protein are induced by strong synaptic activation and rapidly transported into dendrites, where they localize at active synaptic sites. Thus, the Arc mRNA and protein are proposed as a marker of neuronal reactivity to map the neural substrates that are recruited by various stimuli. In the present study, we examined the expression of Arc protein induced by conditioned naloxone-precipitated drug withdrawal in different brain regions of acute morphine-dependent rats. The objective of the present study was to address the specific neural circuits involved in conditioned place aversion （CPA） that has not yet been well characterized. Methods： Place aversion was elicited by conditioned naloxone-precipitated drug withdrawal following exposure to a single dose of morphine. An immunohistochemical method was employed to detect the expression of Arc, which was used as a plasticity marker to trace the brain areas that contribute to the formation of the place aversion. Results： Marked increases in Arc protein levels were found in the medial and lateral prefrontal cortex, the sensory cortex, the lateral striatum and the amygdala. This effect was more pronounced in the basolateral amygdala （BLA）, the central nucleus of the amygdala （CeA）, and the bed nucleus of the striatal terminals （BNST） when compared with the control group. Conclusion： Our results suggest that these brain regions may play key roles in mediating the negative motivational component of opiate withdrawal.     

An improved LC-MS/MS method for quantitative determination of ilaprazole and its metabolites in human plasma and its application to a pharmacokinetic study

Aim： To improve and validate an analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry （LC-ESI-MS/MS） for the quantitative measurement of ilaprazole and its two metablites in human plasma. Methods： Separation of analytes and the internal standard （IS）, omeprazole, was performed on a Thermo HyPURITY C18 column （150×2.1 mm, 5 um） with a mobile phase consisting of 10 mmol/L ammonium formate water-acetonitrile solution （50：50, v/v） at a flow rate of 0.25 mL/min. The API4000 triple quadruple mass spectrometer was operated in multiple reactions monitoring mode via positive electrospray ionization interface using the transition m/z 367.2 → m/z 184.0 for ilaprazole, m/z 383.3 → m/z 184.1 for ilaprazole sulfone, m/z 351.2 → m/z 168.1 for ilaprazole thiol ether and m/z 346.2 → m/z 198.0 for omeprazole. Results： The method was linear over the concentration range of 0.23-2400.00 ng/mL for ilaprazole, 0.05-105.00 ng/mL for ilaprazole thiol ether and 0.06-45.00 ng/mL for ilaprazole sulfone. The intra- and inter-day precisions were all less than 15% in terms of relative standard deviation （RSD）, and the accuracy was within 15% in terms of relative error （RE） for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether. The lower limit of quantification （LLOQ） was identifiable and reproducible at 0.23, 0.05 and 0.06 ng/mL with acceptable precision and accuracy for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether, respectively. Conclusion： The validated method offered sensitivity and a wide linear concentration range. This method was successfully applied for the evaluation of the pharmacokinetics of ilaprazole and its two metabolites after single oral doses of 5 mg ilaprazole to 12 healthy Chinese volunteers.     

Alpha-conotoxins as pharmacological probes of nicotinic acetylcholine receptors

Cysteine-rich peptides from the venom of cone snails （Conus） target a wide variety of different ion channels. One family of conopeptides, the α-conotoxins, specifically target different isoforms of nicotinic acetylcholine receptors （nAChRs） found both in the neuromuscular junction and central nervous system. This family is further divided into subfamilies based on the number of amino acids between cysteine residues. The exquisite subtype selectivity of certain α-conotoxins has been key to the characterization of native nAChR isoforms involved in modulation of neurotransmitter release, the pathophysiology of Parkinson＇s disease and nociception. Structure/function characterization of α-conotoxins has led to the development of analogs with improved potency and/or subtype selectivity. Cyclization of the backbone structure and addition of lipophilic moieties has led to improved stability and bioavailability of α-conotoxins, thus paving the way for orally available therapeutics. The recent advances in phylogeny, exogenomics and molecular modeling promises the discovery of an even greater number of α-conotoxins and analogs with improved selectivity for specific subtypes of nAChRs.     

Cerebral cortex modulation of pain

Pain is a complex experience encompassing sensory-discriminative, affective-motivational and cognitiv e-emotional components mediated by different mechanisms. Contrary to the traditional view that the cerebral cortex is not involved in pain perception, an extensive cortical network associated with pain processing has been revealed using multiple methods over the past decades. This network consistently includes, at least, the anterior cingulate cortex, the agranular insular cortex, the primary （SⅠ） and secondary somatosensory （SⅡ） cortices, the ventrolateral orbital cortex and the motor cortex. These cortical structures constitute the medial and lateral pain systems, the nucleus submedius-ventrolateral orbital cortex-periaqueductal gray system and motor cortex system, respectively. Multiple neurotransmitters, including opioid, glutamate, GABA and dopamine, are involved in the modulation of pain by these cortical structures. In addition, glial cells may also be involved in cortical modulation of pain and serve as one target for pain management research. This review discusses recent studies of pain modulation by these cerebral cortical structures in animals and human.     

Atorvastatin attenuates homocysteine-induced apop- tosis in human umbilical vein endothelial cells via inhibiting NADPH oxidase-related oxidative stress- triggered p38MAPK signaling

Aim： To examine the effect of atorvastatin on homocysteine （Hcy）-induced reactive oxygen species （ROS） production and apoptosis in human umbilical vein endothelial cells （HUVECs）. Methods： HUVECs were cultured with Hcy （0.1-5 retool/L） in the presence or absence of atorvastatin （1-100 pmol/L） or various stress signaling inhibitors, including the nicotinamide adenine dinucleotide phosphate （NADPH） oxidase inhibitor diphenylene iodonium （DPI, 10 μmol/L）, the p38 mitogen-activated protein kinase （p38 MAPK） inhibitor SB203580 （10 μmol/L） and antioxidants N-acetyl cysteine （NAC, I mmol/L）. Cell apoptosis was evaluated by Annexin V/propidium iodide staining and flow cytometry. ROS were detected by 2＇,7＇-dichlorodihydrofluorescein diacetate （H2DCFH-DA）. NADPH oxidases were evaluated with lucigenin-enhanced chemilu- minescence. Hcy-induced expression of p38MAPK protein was measured by Western blotting analysis. Results： Atorvastatin inhibited endothelial cell apoptosis induced by 1 mmol/L Hcy in a dose-dependent manner and the maximal inhibitory effect was reached at 100 pmol/L. Atorvastatin （10 pmol/L） significantly suppressed Hcy （1 mmol/L for 30 min） induced ROS accumulation （3.17±0.33 vs 4.34±0.31, P〈O.05）. Atorvastatin （10 pmol/L） also antagonized Hcy （1 mmol/L for 30 min） induced activation of NADPH oxidase （2.57±0.49 vs 3.33±0.6, P〈O.05）. Furthermore, atorvastatin inhibited Hcy-induced phosphorylation of p38 MAPK （1.7±0.1 vs 2.22±0.25, P〈O.05）, similar effects occurred with DPI, NAC and SB203580. Conclusion： Atorvastatin may inhibit Hcy-induced ROS accumulation and endothelium cell apoptosis through an NADPH oxidase and/or p38MAPK-dependent mechanisms, all of which may contribute to atorvastatin-induced beneficial effect on endothelial function.     

Beta-receptor activation increases sodium current in guinea pig heart

Aim： To study the influence of β-receptor activation on sodium channel current and the physiological significance of increased sodium current with regard to the increased cardiac output caused by sympathetic excitation. Methods： Multiple experimental approaches, including ECG, action potential recording with conventional microelectrodes, whole-cell current measurements, single-channel recordings, and pumping-force measurements, were applied to guinea pig hearts and isolated ventricular myocytes. Results： lsoprenaline was found to dose-dependently shorten QRS waves, increase the amplitude and the Vmax of action potentials, augment the fast sodium current, and increase the occurrence frequencies and open time constants of the long-open and burst modes of the sodium channel. Increased levels of membrane-permeable cAMP have similar effects. In the presence of a calcium channel blocker, TTX reversed the increased pumping force produced by isoprenaline. Conclusion： Beta-adrenergic modulation increases the inward sodium current and accelerates the conduction velocity within the ventricles by changing the sodium channel modes, which might both be conducive to the synchronous contraction of the heart and enhance its pumping function.