The Guiding Significance of Ocular Biometry in Evaluating the Refractive Status of Preschool Children.

INTRODUCTIONS: This study aimed to analyze the correlation between refractive status and ocular biological parameters in preschool-age children (3-6 years old), establish a regression curve, guide the clinical judgment of children's refractive status, and improve the accuracy of refractive screening for this age group. METHODS: A total of 508 children, aged 3-6 years, were admitted to the hospital, exhibiting symptoms of ametropia and a need for dilation optometry. Among these, 326 children were included in the statistics group, having been examined between August 2021 and October 2022, and 182 children were included in the validation group, having been examined between November 2022 and March 2023. Using IOL Master700, ocular biometry parameters were measured for all participants, including axial length (AL), keratometry readings (K1 and K2), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). One percent atropine sulfate eye gel was administered, and then the spherical equivalent (SE) was calculated by Bennett's formula. The correlation between SE and other ocular biometrics was analyzed, followed by the establishment of an SE prediction equation. The SE prediction equation was used to calculate the spherical equivalent (SE#) using ocular biometry data from the validation group, and the consistency between SE and SE# was evaluated. RESULTS: SE showed a negative correlation with AL/CR (r = -0.936), AL (r = -0.811), ACD (r = -0.500), age (r = -0.396), and Km (r = -0.213) (p < 0.001), and positive correlation with LT (r = 0.301), LP (r = 0.176) (p < 0.001). A multiple linear regression equation was established for SE using the stepwise selection method, SE = 49.232 - 23.583 × AL/CR + 1.703 × ACD + 0.589 × Km - 0.609 × LP + 1.103 × LT (R2 = 0.997). Based on the regression equation, the predicted SE# highly correlated with SE after cycloplegia in the validation group (r = 0.998, p < 0.001). CONCLUSION: The main ocular biological factors of ocular diopter in children aged 3-6 years are AL/CR, ACD, Km, LP, and LT, which are jointly influenced by multiple factors. Ocular biometry is a reliable predictor of real refraction among children aged 3-6.

Anti-reflection metallic anode-enhanced performance of organic solar cells via cross coupling between Fabry-Perot cavity modes and microcavity modes.

An effective anti-reflection metallic anode with the structure of glass/dielectric2 /Ag (D1D2M) is demonstrated both in small-molecule (SM) and conjugated polymer (CP) organic solar cells (OSCs). The anti-reflection mechanism is investigated by the finite-difference time-domain numerical calculation method and the experimental method. By tuning the refractive index and the thickness of the D2 layer, the reflection light is confined in the Fabry-Perot (F-P) cavity modes, which effectively enhances the transmittance of the D1D2M anode in the wavelength range of 420 nm-800 nm. Compared with the conventional glass/Ag (D1M) anode, the experimental transmittance of the D1D2M anode is enhanced by 33.24% at a wavelength of 550 nm. By replacing the D1M anode with the D1D2M anode in the OSCs, the F-P cavity modes cross couple with the microcavity modes in the active layers. As a result, the absorption intensity is obviously increasing in a wide angle range (0≤θ≤85∘) in the wavelength ranges of 475 nm-650 nm and 540 nm-720 nm for the SM and CP OSCs, respectively. The short circuit current density and power conversion efficiency of the SM OSC is increased by 25.07% and 27.23%, respectively.

Mettl3 deficiency leads to the upregulation of Cav1.2 and increases arrhythmia susceptibility in mice.

Methyltransferase-like 3 (Mettl3) is a component of methyltransferase complex that mediates mA modification of RNAs, and participates in multiple biological processes. However, the role of Mettl3 in cardiac electrophysiology remains unknown. This study aims to explore the ventricular arrhythmia susceptibility of Mettl3 mice and the underlying mechanisms. Mice were anesthetized with 2% avertin (0.1 mL/ body weight) for echocardiography and programmed electrical pacing. Whole-cell patch clamp technique was used to examine the electrophysiological property of cardiomyocytes. The expression of Cav1.2 was determined by qRT-PCR and western blot analysis. The mA medication of mRNA was examined by MeRIP-Seq and MeRIP-qPCR. No differences are found in the morphology and function of the hearts between Mettl3 mice and wild-type (WT) controls. The QT and QTc intervals of Mettl3 mice are significantly longer. High-frequency electrical stimulation showed that heterozygous knockout of Mettl3 increases ventricular arrhythmia susceptibility. The whole-cell patch-clamp recordings showed that the APD is prolonged in Mettl3 ventricular myocytes and more EADs were observed. The density of is substantially increased in ventricular myocytes of Mettl3 mice. The pore-forming subunit of L-type calcium channel Cav1.2 is upregulated in Mettl3 mice, while the mRNA of its coding gene does not change. MeRIP-Seq and MeRIP-qPCR showed that the mA methylation of mRNA is decreased in cultured Mettl3-knockdown cardiomyocytes and Mettl3 hearts. Collectively, deficiency of Mettl3 increases ventricular arrhythmia susceptibility due to the upregulation of Cav1.2 by reducing mA modification onmRNA in mice. This study highlights the role of mA modification in the regulation of cardiac electrophysiology.

Endothelial peroxynitrite causes disturbance of neuronal oscillations by targeting caspase-1 in the arcuate nucleus.

Severe anorexia limits the clinical application of cisplatin, and even leads to the discontinuation of treatment. However, the mechanisms underlying cisplatin-induced anorexia are unknown. Herein, we demonstrated that cisplatin could affect neuronal gamma oscillations and induce abnormal neuronal theta-gamma phase-amplitude coupling in the arcuate nucleus (Arc) of the hypothalamus, and these findings were associated with significantly decreased food intake and weight loss in mice. Chemogenetic activation of AgRP neurons in the Arc reversed the cisplatin-induced food intake reduction in mice. We further demonstrated that endothelial peroxynitrite (ONOO-) formation in the Arc induced nitrosative stress following cisplatin treatment via a previously uncharacterized pathway involving neuronal caspase-1 activation. Strikingly, treatment with the ONOO- scavenger uric acid (UA) reversed the reduced action potential (AP) frequency of AgRP neurons and increased the AP frequency of POMC neurons induced by SIN1, a donor of ONOO-, in the Arc, as determined by whole-cell patch-clamp electrophysiological recording. Consistent with these findings, UA treatment effectively alleviated cisplatin-induced dysfunction of neuronal oscillations and neuronal theta-gamma phase-amplitude coupling in the Arc of mice. Taken together, these results suggest, for the first time, that targeting the overproduction of endothelial ONOO- can regulate cisplatin-induced neurotoxicity through neuronal caspase-1, and thereby serve as a potential therapeutic approach to alleviate chemotherapy-induced anorexia and weight loss.

Deficiency of CXXC finger protein 1 leads to small changes in heart rate but moderate epigenetic alterations and significant protein downregulation of hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) ion channels in mice.

BACKGROUND: The normal cardiac rhythm is generated in the sinoatrial node (SAN). Changes in ionic currents of the SAN may cause sinus arrhythmia. CXXC finger protein 1 (Cfp1) is an epigenetic regulator that is involved in transcriptional regulation of multiple genes. OBJECTIVE: The purpose of this study was to explore whether Cfp1 controls SAN function through regulation of ion channel-related genes. METHODS: Electrophysiological study, patch clamp recording, reverse transcriptase polymerase chain reaction, optical mapping, chromatin immunoprecipitation, and immunofluorescence staining were performed to evaluate the function of SAN and underlying mechanism on Cfp1 heterozygous knockout (Cfp1+/-) mice. RESULTS: Heart rate was slower slightly and SAN recovery time was longer in Cfp1+/- mice than controls. Whole-cell patch-clamp recording showed that the firing rate of action potentials was reduced in Cfp1+/- mice. The density of If current was reduced by 66% in SAN cells of Cfp1+/- mice but the densities of ICa, ICa-L, and ICa-T were not changed. The hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) mRNA level in SAN tissue of Cfp1+/- mice was reduced. The HCN4 protein was significantly decreased in SAN cells and tissues after heterozygous deletion of Cfp1. Chromatin immunoprecipitation assay on cultured HL-1 cells demonstrated that Cfp1 was enriched in the promoter regions of HCN4. Knockdown of Cfp1 reduced H3K4 trimethylation, H3K9 acetylation, and H3K27 acetylation of HCN4 promoter region. CONCLUSION: Deficiency of Cfp1 leads to small changes in heart rate by moderate epigenetic modification alterations and significant protein downregulation of HCN4 ion channels in mice.

Endothelial Cdk5 deficit leads to the development of spontaneous epilepsy through CXCL1/CXCR2-mediated reactive astrogliosis.

Blood-brain barrier (BBB) dysfunction has been suggested to play an important role in epilepsy. However, the mechanism mediating the transition from cerebrovascular damage to epilepsy remains unknown. Here, we report that endothelial cyclin-dependent kinase 5 (CDK5) is a central regulator of neuronal excitability. Endothelial-specific Cdk5 knockout led to spontaneous seizures in mice. Knockout mice showed increased endothelial chemokine (C-X-C motif) ligand 1 (Cxcl1) expression, decreased astrocytic glutamate reuptake through the glutamate transporter 1 (GLT1), and increased glutamate synaptic function. Ceftriaxone restored astrocytic GLT1 function and inhibited seizures in endothelial Cdk5-deficient mice, and these effects were also reversed after silencing Cxcl1 in endothelial cells and its receptor chemokine (C-X-C motif) receptor 2 (Cxcr2) in astrocytes, respectively, in the CA1 by AAV transfection. These results reveal a previously unknown link between cerebrovascular factors and epileptogenesis and provide a rationale for targeting endothelial signaling as a potential treatment for epilepsy.

The glymphatic system delivery enhances the transduction efficiency of AAV1 to brain endothelial cells in adult mice.

BACKGROUND: Recombinant adeno-associated virus (rAAV) is increasingly applied in neuroscience research or gene therapy. However, there is no simple and efficient tool for specific transfection of rAAV into cerebrovascular tissues. It has been reported that fluorescent tracers or beta-amyloid protein can enter the brain through perivascular spaces, named as "glymphatic system". The purpose of this study was to explore whether rAAV could transduce the cerebral vasculature through the glymphatic pathway. NEW METHOD: An AAV1-GFP vector suspension (15 µL) was injected into the intracisternal space of anesthetized mice (n = 2) and 5 µl was injected into the bulbus medullae (n = 2). As controls, 15 µl of artificial cerebrospinal fluid (aCSF) was injected into the cisterna magna. The endothelial specific transduction was verified by Glut1 or PDGFRß immunofluorescent staining. Immunofluorescence images for all groups were captured with a laser microscope. RESULTS: It was observed that infection with rAAV1 vectors encoding green fluorescence protein resulted in a successful cerebrovascular transduction when injected into cisterna magna, compared to aCSF or intra-parenchymal injection at 30 days post-transduction in adult mice. In addition, GFP was co-localized with Glut1 based on immuno-fluorescence. These results indicate that glymphatic system delivery enhances the transduction efficiency of AAV1 to brain endothelial cells. COMPARISON WITH EXISTING METHODS: The AAV1 vector can simply and efficiently transduce the cerebral endothelial cells through the glymphatic pathway. CONCLUSION: The findings of this study reveal that rAAV1-based vectors have high application potential for endothelial-targeted neurologic disease research or gene-based therapies.

Functional coupling of Tmem74 and HCN1 channels regulates anxiety-like behavior in BLA neurons.

Anxiety disorders are the most prevalent psychiatric disorders, but their pathogenic mechanism remains poorly understood. Here, we report that transmembrane protein 74 (TMEM74), which contains two putative transmembrane domains and exhibits high levels of mRNA in the brain, is closely associated with the pathogenesis of anxiety disorders. TMEM74 was decreased in the serum of patients with anxiety and the basolateral amygdaloid nucleus (BLA) in chronic stress mice. Furthermore, genetic deletion of Tmem74 or selective knockdown of Tmem74 in BLA pyramidal neurons resulted in anxiety-like behaviors in mice. Whole-cell recordings in BLA pyramidal neurons revealed lower hyperpolarization-activated cation current (Ih) and greater input resistance and excitability in Tmem74-/- neurons than in wild-type neurons. Accordingly, surface expression of hyperpolarization-activated cyclic nucleotide-gated 1 (HCN1) channels was also lower in the BLA of Tmem74-/- mice. The Ih current blocker ZD7288 mimicked these effects in BLA pyramidal neurons in wild-type mice but not in Tmem74-/- mice. Consistent with the improvement in anxiety-like behaviors, Tmem74 overexpression restored HCN1 channel trafficking and pyramidal neuron excitability in the BLA of Tmem74-/- and chronic stress mice. Mechanistically, we demonstrate that interactions between Tmem74 and HCN1 are physiologically relevant and that transmembrane domain 1 (TM1) is essential for the cellular membrane localization of Tmem74 to enhance Ih. Together, our findings suggest that Tmem74 coupling with HCN1 acts as a critical component in the pathophysiology of anxiety and is a potential target for new treatments of anxiety disorders.

Cathepsin B inhibition ameliorates leukocyte-endothelial adhesion in the BTBR mouse model of autism.

AIMS: Autism spectrum disorder (ASD) is a wide range of neurodevelopmental disorders involving deficits in social interaction and communication. Unfortunately, autism remains a scientific and clinical challenge owing to the lack of understanding the cellular and molecular mechanisms underlying it. This study aimed to investigate the pathophysiological mechanism underlying leukocyte-endothelial adhesion in autism-related neurovascular inflammation. METHODS: Male BTBR T+tf/J mice were used as an autism model. The dynamic pattern of leukocyte-endothelial adhesion in mouse cerebral vessels was detected by two-photon laser scanning microscopy (TPLSM). Using FACS, RT-PCR, and Western blotting, we explored the expression of cell adhesion molecules, the mRNA expression of endothelial chemokine, the protein levels of cathepsin B, and inflammatory mediators. RESULTS: We found a significant increase in leukocyte-endothelial adhesion in BTBR mice, accompanied by elevated expression of the adhesion molecule neutrophils CD11b and endothelial ICAM-1. Our data further indicate that elevated neutrophil cathepsin B levels contribute to elevated endothelial chemokine CXCL7 levels in BTBR mice. The pharmacological inhibition of cathepsin B reverses the enhanced leukocyte-endothelial adhesion in the cerebral vessels of autistic mice. CONCLUSION: Our results revealed the prominent role of cathepsin B in modulating leukocyte-endothelial adhesion during autism-related neurovascular inflammation and identified a promising novel approach for autism treatment.

Endothelial GPR124 Exaggerates the Pathogenesis of Atherosclerosis by Activating Inflammation.

BACKGROUND/AIMS: Endothelial cell dysfunction is the principal pathological process underlying atherosclerotic cardiovascular disease. G protein-coupled receptor 124 (GPR124), an orphan receptor in the adhesion GPCR subfamily, promotes angiogenesis in the brain. In the present study, we explored the role of endothelial GPR124 in the development and progression of atherosclerosis in adult mice. METHODS: Using tetracycline-inducible transgenic systems, we generated mice expressing GPR124 specifically under control of the Tie-2 promoter. The animal model of atherosclerosis was constructed by intravenously injecting AAV-PCSK9DY into tetracycline-regulated mice and feeding the mice a high-fat diet for 16 consecutive weeks. Biochemical analysis and immunohistochemistry methods were used to address the role and mechanism of GPR124 in the pathological process of atherosclerosis. RESULTS: Higher TC (total cholesterol) and LDL-C (low density lipoprotein cholesterol) levels in serum and greater lipid deposition in the aortic sinus were found in atherosclerotic mice with GPR124 overexpression, coincident with the elevated proliferation of smooth muscle cells. We observed an elevation of ONOO- in the aortic sinus in this model by using immunofluorescence, and the experiments showed that the specific overexpression of GPR124 in the endothelium induced the up-regulation of CD68, NLRP3 and caspase-1 levels in the aortic sinus. CONCLUSION: The above results indicate that manipulating GPR124 in the endothelium may contribute to delayed pathological progression of atherosclerosis.

HIV Tat protein inhibits hERG K+ channels: a potential mechanism of HIV infection induced LQTs.

HIV-infected patients have a high prevalence of long QT syndrome (LQTs). hERG K(+) channel encoded by human ether-a-go-go related gene contributes to IKr K(+) currents responsible for the repolarization of cardiomyocytes. Inhibition of hERG K(+) channels leads to LQTs. HIV Tat protein, the virus transactivator protein, plays a pivotal role in AIDS. The aim of the present study is to examine the effects of HIV Tat protein on hERG K(+) channels stably expressed in HEK293 cells. The hERG K(+) currents were recorded by whole-cell patch-clamp technique and the hERG channel expression was measured by real-time PCR and Western blot techniques. HIV Tat protein at 200 ng/ml concentration showed no acute effect on hERG currents, but HIV Tat protein (200 ng/ml) incubation for 24 h significantly inhibited hERG currents. In HIV Tat incubated cells, the inactivation and the recovery time from inactivation of hERG channels were significantly changed. HIV Tat protein incubation (200 ng/ml) for 24h had no effect on the hERG mRNA expression, but dose-dependently inhibited hERG protein expression. The MTT assay showed that HIV Tat protein at 50 ng/ml and 200 ng/ml had no effect on the cell viability. HIV Tat protein increased reactive oxygen species (ROS) generation and the inhibition of hERG channel protein expression by HIV Tat protein was prevented by antioxidant tempol. HIV Tat protein in vivo treatment reduced IKr currents and prolonged action potential duration of guinea pig cardiomyocytes. We conclude that HIV Tat protein inhibits hERG K(+) currents through the inhibition of hERG protein expression, which might be the potential mechanism of HIV infection induced LQTs.

Difference of sodium currents between pediatric and adult human atrial myocytes: evidence for developmental changes of sodium channels.

Voltage-gated calcium currents and potassium currents were shown to undergo developmental changes in postnatal human and animal cardiomocytes. However, so far, there is no evidence whether sodium currents also presented the developmental changes in postnatal human atrial cells. The aim of this study was to observe age-related changes of sodium currents between pediatric and adult atrial myocytes. Human atrial myocytes were acutely isolated and the whole-cell patch clamp technique was used to record sodium currents isolated from pediatric and adult atrial cardiomocytes. The peak amplitude of sodium currents recorded in adult atrial cells was significantly larger than that in pediatric atrial myocytes. However, there was no significant difference of the activation voltage for peak sodium currents between two kinds of atrial myocytes. The time constants for the activation and inactivation of sodium currents were smaller in adult atria than pediatric atria. The further study revealed that the voltage-dependent inactivation of sodium currents were more slow in adult atrial cardiomyocytes than pediatric atrial cells. A significant difference was also observed in the recovery process of sodium channel from inactivation. In summary, a few significant differences were demonstrated in sodium currents characteristics between pediatric and adult atrial myocytes, which indicates that sodium currents in human atria also undergo developmental changes.

Heme oxygenase-1 transgenic overexpression did not prevent artery injury induced by electric stimulation and pressure overload in mice.

Heme oxygenase-1 (HO-1) shows multiple beneficial effects on cardiovascular diseases. However, the effect of HO-1 on the injury of artery has never been identified. In the present study, we established systemic HO-1 overexpression transgenic mice and investigated the effect of HO-1 on the injury of artery induced by electric stimulation and pressure-overload in transgenic mice. Artery injury was induced by electric stimulation and pressure overload. The contractive function, endothelium-dependent and -independent relaxation of arteries were measured through an isometric force transducer connected to a multichannel acquisition and analysis system. Western blot results showed that HO-1 protein level in transgenic mice arteries was significantly higher than that in wild type mice arteries, while no difference of HO-2 protein level in the arteries of transgenic and wild type mice. Arterial reendothelialization after electric injury was accelerated in transgenic mice. No significant difference in contractive function, endothelium-dependent and -independent relaxation of arteries was observed between wild type and transgenic mice at day 7 after electric injury and 4 weeks after pressure overload. We concluded that HO-1 overexpression accelerated the reendothelialization, but did not prevent the functional impairment of injured artery in mice.

Homocysteine modulates sodium channel currents in human atrial myocytes.

Hyperhomocysteinemia has been proposed as an important risk factor for cardiac arrhythmias and ischemia worldwide. However, the cellular mechanism underlying toxic effects of homocysteine on hearts remains conjectural. It is well known that aberrant sodium channels can promote the development of cardiac arrhythmias and ischemic injury. So the present study was to investigate toxic effects of homocysteine on sodium currents recorded in human atrial cells. Human atrial myocytes were acutely enzymatically isolated and the whole-cell patch clamp technique was employed to record sodium currents and membrane potential in human atrial cells in the absence and presence of homocysteine. We found that in human atrial myocytes, sodium currents were significantly increased by pathological concentration of homocysteine with the maximum activation potential shifted toward the positive potential. However, physiological concentration of homocysteine did not have any effects on sodium currents. The time constants for time-dependent activation (tau(act)) and inactivation (tau(inact)) of sodium currents were both markedly shortened by elevated homocysteine levels. The further channel kinetic data showed that elevated homocysteine levels shifted the inactivation curve towards positive potential and accelerated the recovery from inactivation of sodium channel, but did not affect the activation of sodium channel. Additionally, the resting membrane potential of human atrial myocytes was obviously depolarized by elevated homocysteine levels in the current clamp model. Taken together, the data presented in this study first revealed that increased homocysteine levels caused the abnormality of sodium currents in human atrial cells by slowing the inactivation and promote the recovery of sodium channels, which provides a better understanding of hyperhomocysteinemia associated cardiac arrhythmias and ischemia.

Characterization and comparison of Na+, K+ and Ca2+ currents between myocytes from human atrial right appendage and atrial septum.

Atrial pacing to reduce paroxysmal atrial fibrillation recurrences is performed in right atrial appendage (RAA) traditionally. However, recent studies indicate that atrial septal (AS) pacing produces better outcomes than the RAA pacing. The underlying mechanisms for this difference remained unclear. One possible explanation for the superiority of AS pacing over RAA pacing is that the two different regions have distinct electrophysiological properties. The study was to explore whether there indeed exist regional differences of electrical activities between RAA and AS, using whole-cell patch clamp techniques. The results showed that RAA cells had longer action potential duration, more negative resting potential and greater amplitude of action potential, whereas AS cells had more rapid depolarizing velocity. The sodium current was significantly smaller in RAA cells, whereas the calcium current was markedly smaller in AS cells. The transient outward K(+) current was similar in both regions. The ultrarapid delayed rectifier K(+) current was greater in RAA than that in AS cells. The inward rectifier K(+) current was similar at potentials more negative to -60 mV in both regions. The results indicate that RAA and AS of patients with rheumatic heart disease possess distinct electrophysiological properties. These differences provided a rational explanation for the different efficacies in treating atrial fibrillation by atrial pacing in RAA and AS regions.

Homocysteine inhibits potassium channels in human atrial myocytes.

1. A large body of evidence indicates that elevated homocysteine (Hcy) levels portend an increased risk for atrial fibrillation. However, little is known about the electrophysiological effects of Hcy on atrial myocytes. The present study was conducted to investigate the direct effects of Hcy on ion channels in human atria. 2. Whole-cell patch-clamp techniques were used to record potassium currents in human atrial cells. 3. In human atrial myocytes, transient outward potassium currents were significantly decreased by 24.8 +/- 5.9 and 38.4 +/- 10.4% in the presence of 50 and 500 micromol/L Hcy, respectively. The ultrarapid delayed rectifier potassium currents were decreased by approximately 30% when exposed to 500 micromol/L Hcy. The inward rectifier potassium currents were increased by approximately 40% in the presence of 500 micromol/L Hcy. 4. The results of the present study indicate that Hcy, an important risk factor for atrial fibrillation, could cause electrophysiological disturbances of potassium currents in human atrial myocytes.

Large-conductance Ca2+-activated K+ currents blocked and impaired by homocysteine in human and rat mesenteric artery smooth muscle cells.

Plenty of evidence suggests that increased blood levels of homocysteine (Hcy) are an independent risk factor for the development of vascular diseases, but the underlying mechanisms are not well understood. It is well known that the larger conductance Ca(2+)-activated K(+) channels (BK(Ca)) play an essential role in vascular function, so the present study was conducted to determine direct effects of Hcy on BK(Ca) channel properties of smooth muscle cells. Whole-cell patch-clamp recordings were made in mesenteric artery smooth muscle cells isolated from normal rat and patients to investigate effects of 5, 50 and 500 microM Hcy on BK(Ca), the main current mediating vascular responses in these cells. In human artery smooth muscle cells, maximum BK(Ca) density (measured at +60 mV) was inhibited by about 24% (n=6, P<0.05). In rat artery smooth muscle cells, maximum BK(Ca) density was decreased by approximately 27% in the presence of 50 microM Hcy (n=8, P<0.05). In addition, when rat artery smooth muscle cells was treated with 50 microM Hcy for 24 h, maximum BK(Ca) density decreased by 58% (n=5, P<0.05). These data suggest that Hcy significantly inhibited BK(Ca) currents in isolated human and rat artery smooth muscle cells. BK(Ca) reduced and impaired by elevated Hcy levels might contribute to abnormal vascular diseases.

Involvement of calcium-sensing receptor in ischemia/reperfusion-induced apoptosis in rat cardiomyocytes.

The calcium-sensing receptor (CaR) is a seven-transmembrane G-protein coupled receptor, which activates intracellular effectors, for example, it causes inositol phosphate (IP) accumulation to increase the release of intracellular calcium. Although intracellular calcium overload has been implicated in the cardiac ischemia/reperfusion (I/R)-induced apoptosis, the role of CaR in the induction of apoptosis has not been fully understood. This study tested the hypothesis that CaR is involved in I/R cardiomyocyte apoptosis by increasing [Ca2+]i. The isolated rat hearts were subjected to 40-min ischemia followed by 2 h of reperfusion, meanwhile GdCl3 was added to reperfusion solution. The expression of CaR increased at the exposure to GdCl3 during I/R. By laser confocal microscopy, it was observed that the intracellular calcium was significantly increased and exhibited a Deltapsim, as monitored by 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolcarbocyanine iodide (JC-1) during reperfusion with GdCl3. Furthermore, the number of apoptotic cells was significantly increased as shown by TUNEL assay. Typical apoptotic cells were observed with transmission electron microscopy in I/R with GdCl3 but not in the control group. The expression of cytosolic cytochrome c and activated caspase-9 and caspase-3 was significantly increased whereas the expression of mitochondrial cytochrome c significantly decreased in I/R with GdCl3 in comparison to the control. In conclusion, these results suggest that CaR is involved in the induction of cardiomyocyte apoptosis during ischemia/reperfusion through activation of cytochrome c-caspase-3 signaling pathway.

[Comparison of the anti-arrhythmic effects of matrine and berbamine with amiodarone and RP58866].

AIM: To clarify mechanisms that the antiarrhythmic effects of matrine and berbamine are weaker than those of amiodarone and RP58866. METHODS: Experimental arrhythmic models were induced by aconitine, coronary artery ligation and electric stimulation in rats and rabbits. Whole-cell patch-clamp techniques were used to record IK1, IKr, IKs and Ito. RESULTS: Matrine and berbamine significantly increased the dose of aconitine for induction of ventricular premature and ventricular tachycardia in rats, decreased the number of arrhythmias induced by coronary artery ligation in rats and increased ventricular fibrillation threshold (VFT) induced by electric stimulation in rabbits, but the anti-arrhythmic potency of matrine and berbamine was lower than that of amiodarone and RP58866. The inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866. The IC50 of matrine for IK1, IKr, IKs, Ito were (46 +/- 3), (32.9 +/- 1.2), (37 +/- 8) and (7.6 +/- 0.5) mol x L(-1), respectively. The IC50 of amiodarone for IK1, IKr, IKs, Ito were (21 +/- 5) , (3.7 +/- 0.7), (5.9 +/- 0.9) and (5.9 +/- 0.6) mol x L(-1), respectively. CONCLUSION: The inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866, which might be the reason that the antiarrhythmic effects of matrine and berbamine were weaker than those of amiodarone and RP58866.