Iridium(III) complex induces apoptosis in HeLa cells by regulating mitochondrial and PI3K/AKT signaling pathways: In vitro and in vivo experiments.

Cyclometalated iridium complexes with mitochondrial targeting show great potential as substitutes for platinum-based complexes because of their strong anti-cancer properties. Three novel cyclometalated iridium(III) compounds were synthesized and evaluated in five different cell lines as part of the ongoing systematic investigations of these compounds. The complexes were prepared using 4,7-dichloro-1,10-phenanthroline ligands. The cytotoxicity of complexes Ir1-Ir3 towards HeLa cells was shown to be high, with IC50 values of 0.83±0.06, 4.73±0.11, and 4.95±0.62 µM, respectively. Complex Ir1 could be ingested by HeLa cells in 3 h and has shown high selectivity toward mitochondria. Subsequent investigations demonstrated that Ir1 triggered apoptosis in HeLa cells by augmenting the generation of reactive oxygen species (ROS), reducing the mitochondrial membrane potential, and depleting ATP levels. Furthermore, the movement of cells was significantly suppressed and the progression of the cell cycle was arrested in the G0/G1 phase following the administration of Ir1. The Western blot analysis demonstrated that the induction of apoptosis in HeLa cells by Ir1 involves the activation of the mitochondria-dependent channel and the PI3K/AKT signaling pathway. No significant cytotoxicity was observed in zebrafish embryos at concentrations less than or equal to 16 µM, e.g., survival rate and developmental abnormalities. In vivo, antitumor assay demonstrated that Ir1 suppressed tumor growth in mice. Therefore, our work shows that complex Ir1 could be a promising candidate for developing novel antitumor drugs.

Dendrobium officinale polysaccharide-based carrier to enhance photodynamic immunotherapy.

Photodynamic therapy (PDT) eradicates tumors via the generation of toxic reactive oxygen species (ROS) by activation of a photosensitizer (PS) with appropriate light. Local PDT toward tumors can trigger the immune response to inhibit distant tumors, but the immune response is usually insufficient. Herein, we used a biocompatible herb polysaccharide with immunomodulatory activity as the carrier of PS to enhance the immune inhibition of tumors after PDT. The Dendrobium officinale polysaccharide (DOP) is modified with hydrophobic cholesterol to serve as an amphiphilic carrier. The DOP itself can promote dendritic cell (DC) maturation. Meanwhile, TPA-3BCP are designed to be cationic aggregation-induced emission PS. The structure of one electron-donor linking to three electron-acceptors endows TPA-3BCP with high efficiency to produce ROS upon light irradiation. And the nanoparticles are designed with positively charged surfaces to capture antigens released after PDT, which can protect the antigens from degradation and improve the antigen-uptake efficiency by DCs. The combination of DOP-induced DC maturation and antigen capture-increased antigen-uptake efficiency by DCs significantly improves the immune response after DOP-based carrier-mediated PDT. Since DOP is extracted from the medicinal and edible Dendrobium officinale, the DOP-based carrier we designed is promising to be developed for enhanced photodynamic immunotherapy in clinic.

Anti-colon Cancer Effects of Dendrobium officinale Kimura & Migo Revealed by Network Pharmacology Integrated With Molecular Docking and Metabolomics Studies.

Objective: The present study aimed to investigate the potential mechanism of Dendrobium officinale (D. officinale) on colorectal cancer and the relevant targets in the pathway using a network pharmacological approach. Methods: (1) We identified the major bioactive components of D. officinale by UPLC-ESI-MS/MS and established the in-house library by using the literature mining method. (2) Target prediction was performed by SwissADME and SwissTargetPrediction. (3) A protein-protein interaction (PPI) network and component-target-pathway network (C-T-P network) were constructed. (4) The GO pathways and the KEGG pathway enrichment analysis were carried out by the Metascape database. (5) Molecular docking was performed by AutoDock software. (6) A series of experimental assays including cell proliferation, cell invasion and migration, and TUNEL staining in CRC were performed in CRC cell lines (HT-29, Lovo, SW-620, and HCT-116) to confirm the inhibitory effects of D. officinale. Results: (1) In total, 396 candidate active components of D. officinale were identified by UPLC-ESI-MS/MS and selected from the database. (2) From OMIM, GeneCards, DrugBank, and TTD databases, 1,666 gene symbols related to CRC were gathered, and (3) 34 overlapping gene symbols related to CRC and drugs were obtained. (4) These results suggested that the anti-CRC components of D. officinale were mainly apigenin, naringenin, caffeic acid, γ-linolenic acid, α-linolenic acid, cis-10-heptadecenoic acid, etc., and the core targets of action were mainly ESR1, EGFR, PTGS2, MMP9, MMP2, PPARG, etc. (5) The proliferation of muscle cells, the regulation of inflammatory response, the response of cells to organic cyclic compounds, and the apoptotic signaling pathway might serve as principal pathways for CRC treatment. (6) The reliability of some important active components and targets was further validated by molecular docking. The molecular docking analysis suggested an important role of apigenin, naringenin, PTGS2, and MMP9 in delivering the pharmacological activity of D. officinale against CRC. (7) These results of the evaluation experiment in vitro suggested that D. officinale had a strong inhibitory effect on CRC cell lines, and it exerted anti-CRC activity by activating CRC cell apoptosis and inhibiting CRC cell migration and invasion. Conclusion: This study may provide valuable insights into exploring the mechanism of action of D. officinale against CRC.

Epimedin C Alleviates Glucocorticoid-Induced Suppression of Osteogenic Differentiation by Modulating PI3K/AKT/RUNX2 Signaling Pathway.

Secondary osteoporosis is triggered mostly by glucocorticoid (GC) therapy. Dexamethasone (DEX) was reported to inhibit osteogenic differentiation in zebrafish larvae and MC3T3-E1 cells in prior research. In this research, we primarily examined the protective impacts of epimedin C on the osteogenic inhibition impact of MC3T3-E1 cells and zebrafish larvae mediated by DEX. The findings illustrated no apparent toxicity for MC3T3-E1 cells after administering epimedin C at increasing dosages from 1 to 60 µM and no remarkable proliferation in MC3T3-E1 cells treated using DEX. In MC3T3-E1 cells that had been treated using DEX, we discovered that epimedin C enhanced alkaline phosphatase activities and mineralization. Epimedin C could substantially enhance the protein expression of osterix (OSX), Runt-related transcription factor 2 (RUNX2), and alkaline phosphatase (ALPL) in MC3T3-E1 cells subjected to DEX treatment. Additionally, epimedin C stimulated PI3K and AKT signaling pathways in MC3T3-E1 cells that had been treated using DEX. Furthermore, in a zebrafish larvae model, epimedin C was shown to enhance bone mineralization in DEX-mediated bone impairment. We also found that epimedin C enhanced ALPL activity and mineralization in MC3T3-E1 cells treated using DEX, which may be reversed by PI3K inhibitor (LY294002). LY294002 can also reverse the protective impact of epimedin C on DEX-mediated bone impairment in zebrafish larval. These findings suggested that epimedin C alleviated the suppressive impact of DEX on the osteogenesis of zebrafish larval and MC3T3-E1 cells via triggering the PI3K and AKT signaling pathways. Epimedin C has significant potential in the development of innovative drugs for the treatment of glucocorticoid-mediated osteoporosis.

Characteristics of Anti-Contactin1 Antibody-Associated Autoimmune Nodopathies With Concomitant Membranous Nephropathy.

Background: The concurrence of anti-contactin 1 (CNTN1) antibody-associated chronic inflammatory demyelinating polyneuropathy (CIDP) and membranous nephropathy (MN) has previously been reported in the literature. CIDP with autoantibodies against paranodal proteins are defined as autoimmune nodopathies (AN) in the latest research. In view of the unclear relationship between CIDP and MN, we performed a case study and literature review to investigate the clinical characteristics of anti-CNTN antibody-associated AN with MN. Methods: We detected antibodies against NF155, NF186, CNTN1, CNTN2, CASPR1 and PLA2R in blood samples of a patient with clinically manifested MN and concomitant peripheral neuropathy via double immunofluorescence staining and conducted a quantitative measurement of anti-PLA2R IgG antibodies via enzyme-linked immunosorbent assay (ELISA). Case reports of anti-CNTN1 antibody-associated AN, anti-CNTN1 antibody-associated AN with MN, and CIDP with MN were retrieved through a literature search for a comparative analysis of clinical characteristics. The cases were grouped according to the chronological order of CIDP and MN onset for the comparison of clinical characteristics. Results: A 57-year-old man with anti-PLA2R positive MN was admitted to the hospital due to limb numbness, weakness, and proprioceptive sensory disorder. He was diagnosed with anti-CNTN1 antibody-associated AN and recovered well after immunotherapy. Our literature search returned 22 cases of CIDP with MN that occurred before, after, or concurrently with CIDP. Good responses were achieved with early single-agent or combination immunotherapy, but eight out of the 22 patients with CIDP and concomitant MN ultimately developed different motor sequelae. Five patients had anti-CNTN1 antibody-associated AN with MN. Among these patients, males accounted for the majority of cases (male:female=4:1), the mean age at onset was late (60.2 ± 15.7 years, range 43-78 years), and 40% had acute to subacute onset. Clinical manifestations included sensory-motor neuropathy, sensory ataxia caused by proprioceptive impairment, and elevated cerebrospinal fluid protein levels. Conclusion: The age at onset of CIDP with MN was earlier than that of anti-CNTN1 antibody-associated AN. MN may occur before, after or concurrently with CIDP. The early detection and isotyping of anti-CNTN1 and anti-PLA2R antibodies and the monitoring of isotype switching may be essential for suspected CIDP patients.

Clinical Efficacy and Safety of Human Mesenchymal Stem Cell Therapy for Degenerative Disc Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Degenerative disc disease (DDD) can cause severe low back pain, which will have a serious negative impact on the ability to perform daily tasks or activities. For the past few years, mesenchymal stem cell (MSC) transplantation has emerged as a promising strategy for the treatment of DDD. However, the clinical efficacy of MSC in the treatment of DDD still lacks clinical evidence and is controversial. We conducted a meta-analysis with randomized controlled trials (RCTs) to evaluate the clinical efficacy and safety of MSC transplantation in patients with DDD. We searched major databases using terms from the database's inception through March 2021. The Cochrane bias risk assessment tool was used to assess quality. The analysis showed that MSC therapy could decrease visual analog scale (VAS) scores (SMD = -0.50, 95%CI = -0.68 ~ -0.33, P < 0.00001) and Oswestry Disability Index (ODI) scores (SMD = -0.27, 95%CI = -0.44 ~ -0.09, P = 0.003). The outcomes with subgroup analysis showed that MSC therapy could decrease VAS scores in 3 months (P = 0.001), 6 months (P = 0.01), 12 months (P = 0.02), and ≥24 months (P = 0.002) and ODI scores in ≥24 months (P = 0.006). Pooled analysis showed that MSC therapy has a higher ratio of patients at most thresholds but particularly at the MIC (minimally important change) (P = 0.0002) and CSC (clinically significant change) (P = 0.0002) in VAS and MIC (P = 0.0005) and CSC (P = 0.001) pain responders in ODI. Adverse events (AE) of treatment-emergent adverse events (TEAE), back pain, arthralgia, and muscle spasms were not statistically significant between the two groups. However, our further statistical analysis showed that MSC therapy may induce AE of TEAE related to study treatment (OR = 3.05, 95%CI = 1.11 ~ 8.40, P = 0.03). In conclusion, this study pooled the main outcomes and showed that MSC therapy could significantly decrease VAS and ODI scores in patients with DDD. Distinctly, the findings of this meta-analysis suggest a novel therapeutic strategy for patients with chronic low back pain (LBP) and lumbar dysfunction by DDD.

Effect of P2Y12 inhibitor monotherapy versus dual antiplatelet therapy on cardiovascular events in patients undergoing percutaneous coronary intervention: systematic review and meta-analysis.

INTRODUCTION: Clinical data on short mandatory dual antiplatelet therapy (DAPT) followed by P2Y12 inhibitor monotherapy, compared with prolonged DAPT in patients undergoing percutaneous coronary intervention (PCI) are insufficient. We aim to evaluate the effectiveness and safety of P2Y12 inhibitor monotherapy and prolonged DAPT after short mandatory DAPT on cardiovascular events in patients undergoing PCI. EVIDENCE ACQUISITION: A systematic literature search was performed in seven medical databases from building the database until July 2019. Three studies with randomized controlled trial (RCTs), totaling 21,970 patients, were included in this meta-analysis. The included studies were assessed by the Cochrane risk of bias and analyzed by Review Manager v. 5.3 software. EVIDENCE SYNTHESIS: Our result of pooled analysis showed that there was noninferior rates of in major adverse cardiac and cerebrovascular events (MACCE), stroke, myocardial infarction and cardiac death between short mandatory DAPT followed by P2Y12 inhibitor monotherapy and prolonged DAPT in patients undergoing PCI. Pooled analysis showed that short mandatory DAPT followed by P2Y12 inhibitor monotherapy could significantly reduce the risk of bleeding BARC type 2-5 (OR=0.47, 95% CI: 0.31-0.70, P=0.002), compared with prolonged DAPT in patients undergoing PCI. However, Pooled analysis showed that short mandatory DAPT followed by P2Y12 inhibitor monotherapy was not associated with BARC type 3-5, compared with prolonged DAPT. CONCLUSIONS: This meta-analysis demonstrated that short mandatory DAPT followed by P2Y12 inhibitor monotherapy compared with prolonged DAPT resulted in noninferior rates of MACCE, all-cause mortality, cardiac death, stroke, myocardial infarction and stent thrombosis. Furthermore, short mandatory DAPT followed by P2Y12 inhibitor monotherapy could significantly reduce the risk of bleeding BARC type 2-5.

Network Pharmacology-Based Study on the Molecular Biological Mechanism of Action for Compound Kushen Injection in Anti-Cancer Effect.

BACKGROUND Compound Kushen injection (CKI) is a traditional Chinese medicine preparation for clinical treatment of cancer pain or treatment of various types of solid tumors. The purpose of this study was to identify the main active compounds from CKI and to investigate its anti-cancer mechanisms via drug target biological network pharmacology construction and prediction. MATERIAL AND METHODS Constituents of CKI were retrieved from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. Disease targets were collected in the Human Gene (Gene Cards) and Human Mendelian Inheritance (OMIM) databases. "Ingredients-protein targets-pathway" networks were constructed using Cytoscape. STRING database platform to construct enrichment of protein-protein interactions (PPI), related diseases and pathways network. Gene Ontology (GO) biological functions and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of were performed to investigate by using Bioconductor tool for analysis. RESULTS The results indicated that 60 constituents of absorption, distribution, metabolism, and excretion (ADME) filtration resulted in 33 constituents exhibiting significant correlations with anti-cancer and CKI may target 113 proteins, including IL6, EGFR, CASP3, VEGFA, MYC, and ESR1. GO and KEGG enrichment analysis results show that 129 biological processes and 93 signal pathways associated with cancer. It mainly involves cancers such as prostate cancer, bladder cancer, hepatocellular carcinoma, colorectal cancer, breast cancer, etc. Active ingredients might also induce apoptosis in cancer cells via the p53 and PI3K-Akt signaling pathway mechanism. CONCLUSIONS This study was based on pharmacological networks results for the prediction of the multi-constituent, multi-target, and multi-pathway mechanisms of CKI, which might be a promising potential therapeutic and prevention candidate for anti-cancer. However, based on computer data mining and analysis, this study still needs to be further verified by in vivo/in vitro experiments, and the safety of CKI needs to be evaluated.

[Genotypes of adenoviruses in infants and young children with diarrhea].

OBJECTIVE: To investigate the prevalence of adenoviruses (AdV) and their genotypes in infants and young children with diarrhea. METHODS: A total of 380 children with diarrhea aged less than 3 years were enrolled. The genomic DNA was extracted from stool and PCR was used to detect AdV. Clone sequencing and genotyping were performed for DNA in AdV-positive specimens. RESULTS: AdV was detected in 24 out of 380 specimens, and the detection rate was 6.3% (24/380). A majority of children with positive AdV were aged 2-3 years. The viral sequence analysis of positive specimens showed that the detection rates of enteric AdV41 and non-enteric AdV were 4.2% (16/380) and 2.1% (8/380), respectively, and among the children with non-enteric AdV, there were 2 with AdV1, 2 with AdV2, 1 with AdV7, 2 with AdV12, and 1 with AdV31. CONCLUSIONS: Diarrhea caused by AdV is commonly seen in children aged 2-3 years, and AdV41 is the major predominant strain.

Hydrogen sulfide in the rostral ventrolateral medulla inhibits sympathetic vasomotor tone through ATP-sensitive K+ channels.

Hydrogen sulfide (H(2)S) acts as an endogenous gaseous transmitter in the central nervous system and plays important roles in regulating cardiovascular function. The rostral ventrolateral medulla (RVLM) is a putative critical central region in the control of sympathetic vasomotor tone and plays an important role in the baroreflex by integrating the inputs from a variety of visceral and somatic stimuli. In this study, we tested the hypothesis that H(2)S decreases sympathetic vasomotor tone through ATP-sensitive potassium channels (K(ATP)) in the RVLM. The arterial blood pressure (ABP), heart rate (HR), and renal sympathetic nerve activity (RSNA) of anesthetized rats were recorded. Bilateral microinjections of sodium hydrosulfide (NaHS; 4, 8, and 16 mM, 50 nl), an H(2)S donor, into the RVLM decreased ABP, HR, and RSNA in a dose-dependent manner. Preinjection of glibenclamide (40 µM, 50 nl), a K(ATP) channel blocker, abolished the sympathoinhibitory effects of NaHS (8 mM, 50 nl). Preinjection of a nitric-oxide synthase inhibitor, N(ω)-nitro-l-arginine methyl ester (200 µM, 50 nl) partially inhibited the sympathoinhibitory effects of NaHS. Prior microinjection of 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-[trifluoromethyl]phenyl)pyridine-3-carboxylic acid methyl ester (Bay K8644) (1 µM, 50 nl), an agonist of Ca(2+) channels, did not alter the effects of NaHS. Infusion of hydroxylamine (30 mM, 50 nl), a cystathionine ß-synthase inhibitor, increased ABP, HR, and RSNA. Taken together, these findings suggest that exogenous H(2)S in the RVLM inhibits sympathetic vasomotor tone by opening K(ATP) channels. Nitric-oxide signaling may partially be involved in the sympathoinhibitory effect of H(2)S in the RVLM.

Electrophysiological effects of hydrogen sulfide on human atrial fibers.

BACKGROUND: It has been reported that endogenous or exogenous hydrogen sulfide (H(2)S) exerts physiological effects in the vertebrate cardiovascular system. We have also demonstrated that H(2)S acts as an important regulator of electrophysiological properties in guinea pig papillary muscles and on pacemaker cells in sinoatrial nodes of rabbits. This study was to observe the electrophysiological effects of H(2)S on human atrial fibers. METHODS: Human atrial samples were collected during cardiac surgery. Parameters of action potential in human atrial specialized fibers were recorded using a standard intracellular microelectrode technique. RESULTS: NaHS (H(2)S donor) (50, 100 and 200 µmol/L) decreased the amplitude of action potential (APA), maximal rate of depolarization (V(max)), velocity of diastolic (phase 4) depolarization (VDD) and rate of pacemaker firing (RPF), and shortened the duration of 90% repolarization (APD(90)) in a concentration-dependent manner. ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide (Gli, 20 µmol/L) partially blocked the effects of NaHS (100 µmol/L) on human atrial fiber cells. The L-type Ca(2+) channel agonist Bay K8644 (0.5 µmol/L) also partially blocked the effects of NaHS (100 µmol/L). An inhibitor of cystathionine γ-lyase (CSE), DL-propargylglycine (PPG, 200 µmol/L), increased APA, V(max), VDD and RPF, and prolonged APD(90). CONCLUSIONS: H(2)S exerts a negative chronotropic action and accelerates the repolarization of human atrial specialized fibers, possibly as a result of increases in potassium efflux through the opening of K(ATP) channels and a concomitant decrease in calcium influx. Endogenous H(2)S may be generated by CSE and act as an important regulator of electrophysiological properties in human atrial fibers.

[Influences of Panax notoginsenosid on spontaneous contraction of small intestine smooth muscle of rabbits in vitro].

OBJECTIVE: To observe the influences of Panax notoginsenosid(a compound of Chinese Traditional Medicine) on the spontaneous contraction of small intestine smooth muscle of rabbits in vitro and explore the mechanism. METHODS: The influences of Panax notoginsenosid on the spontaneous contraction of small intestine in intacted rabbits(male or female) after the isothermal perfuse of small intestine in vitro were observed. Bay K8644 and nitro-L-arginine methylester (L-NAME) were added to the normal Tyrode's solution respectively before Panax notoginsenosid. In the Ca2+ free Tyrode's solution, rynodine was added before Panax notoginsenosid. The mechanism of Panax notoginsenosid was studied. RESULTS: Panax notoginsenosid reduced the amplitude of contraction of small intestine smooth muscle in rabbits in a does-depended manner. Bay K8644 and L-NAME could completely block the inhibition of Panax notoginsenosid on the contraction of small intestine smooth muscle. Panax notoginsenosid inhibited significantly the intracellular calcium-depended contraction induced by rynodine in the Ca2+ free Tyrode's solution. CONCLUSION: Panax notoginsenosid inhibits significantly the contraction of small intestine smooth muscle of rabbits in vitro. The mechanism may be related to increase NO concentration in small intestine smooth muscle so that inhibit extracellular Ca2+ inflowing via cell membrane and intracellular Ca2+ releasing via sarcoplasmic reticulum.

[Mechanisms underlying blood pressure control of cardiovascular centers].

This review systematically introduces the functional connections among cardiovascular centers from spinal cord to cortex, and the mechanisms underlying pressor or depressor response of these cardiovascular centers, including the pathways, transmitters and receptors involved. The pressor or depressor response of these cardiovascular centers is mainly mediated by RVLM-sympathetic vasoconstrictor nerve system.

Effects of ginkgolide B on neuronal discharges in paraventricular nucleus of rat hypothalamic slices.

OBJECTIVE: To study the central role of ginkgolide B (BN52021) in regulating cardiovascular function of nerve center by examining the effects of ginkgolide B on the electrical activity of rat paraventricular nucleus (PVN) neurons in hypothalamic slice preparation and to elucidate the mechanism involved. METHODS: Extracellular single-unit discharge recording technique. RESULTS: (1) In response to the application of ginkgolide B (0.1, 1, 10 micromol/L; n = 27) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 26 (26/27, 96.30%) neurons were significantly decreased in a dose-dependent manner. (2) Pretreatment with L-glutamate (L-Glu, 0.2 mmol/L) led to a marked increase in the SDR of all 8 (100%) neurons in an epileptiform pattern. The increased discharges were suppressed significantly after ginkgolide B (1 micromol/L) was applied into the perfusate for 2 min. (3) In 8 neurons, perfusion of the selective L-type calcium channel agonist, Bay K 8644 (0.1 micromol/L), induced a significant increase in the discharge rates of 8 (8/8, 100%) neurons, while ginkgolide B (1 micromol/L) applied into the perfusate, could inhibit the discharges of 8 (100%) neurons. (4) In 8 neurons, the broad potassium channels blocker, tetraethylammonium (TEA, 1 mmol/L) completely blocked the inhibitory effect of ginkgolide B (1 micromol/L). CONCLUSION: These results suggest that ginkgolide B can inhibit the electrical activity of paraventricular neurons. The inhibitory effect may be related to the blockade of L-type voltage-activated calcium channel and potentially concerned with delayed rectifier potassium channel (K(DR)).

Electrophysiological effects of hydrogen sulfide on pacemaker cells in sinoatrial nodes of rabbits.

The cardiac electrophysiological effects of hydrogen sulfide (H(2)S) on pacemaker cells in sinoatrial (SA) nodes of rabbits were examined using intracellular microelectrode technique. The results obtained were as follows: (1) The velocity of diastolic (phase 4) depolarization (VDD) and rate of pacemaker firing (RPF) in normal pacemaker cells in SA nodes were decreased by NaHS (H(2)S donor) (50, 100, 200 µmol/L) in a concentration-dependent manner; (2) ATP-sensitive K(+) (K(ATP)) channel blocker glybenclamide (Gli, 20 µmol/L) blocked the effect of NaHS (100 µmol/L) on pacemaker cells; (3) Pretreatment with CsCl (2 mmol/L), a blocker of pacemaker current (I(f)), did not affect the effect of NaHS (100 µmol/L) on SA node pacemaker cells; (4) DL-propargylglycine (PPG, 200 µmol/L), an inhibitor of cystathionine γ-lyase (CSE), did not affect the parameters of action potentials in pacemaker cells in SA nodes. All these results suggest that H(2)S exerts a negative chronotropic action on pacemaker cells in SA nodes of rabbits. These effects are likely due to an increase in potassium efflux through opening K(ATP) channels; I(f)is unlikely to play a major role in these effects. In our study, there was no evidence for the generation of endogenous H(2)S by CSE in SA node pacemaker cells.

Resveratrol inhibits electrical activity of paraventricular nucleus neurons in rat hypothalamic slices.

To study the role of resveratrol in the discharges of neurons in paraventricular nucleus (PVN) in hypothalamic slices, extracellular single-unit discharge recording technique was used. The effects of resveratrol were examined with glass microelectrodes in the rat PVN neurons at resting potential level. The results were as follows: (1) In response to the application of resveratrol (0.05, 0.5, 5.0 µmol/L, n=29) to the superfusate for 2 min, the spontaneous discharge rate (SDR) of neurons in 28/29 (96.6%) hypothalamic slices significantly decreased in a dose-dependent manner; (2) Pretreatment with L-glutamate (0.2 mmol/L) led to a marked increase in the SDR in all 8/8 (100%) slices in an epileptiform pattern. The increased discharges were suppressed by the application of resveratrol (5.0 mmol/L) in all 8 slices; (3) In 8 slices, perfusion of the selective L-type calcium channel agonist, Bay K8644 (0.1 µmol/L), induced a significant increase in the discharge rate in 8/8 (100%) slices. Resveratrol (5.0 µmol/L) significantly attenuated the increased SDR in all 8 slices; (4) Pretreatment with the nitric oxide synthase (NOS) inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME, 50 µmol/L) increased SDR in 7/8 (87.5%) slices, but did not affect the inhibitory effect of resveratrol (5.0 µmol/L). These results suggest that resveratrol inhibits the electrical activity of PVN neurons and exerts neuroprotective actions on central neurons. The inhibitory effect of resveratrol is possibly related to the blockade of L-type calcium channel, but not due to NO release.

Ginkgolide B inhibits carotid sinus baroreflex in anesthetized male rats.

The effects of ginkgolide B on the carotid sinus baroreflex (CSB) were studied in the perfused isolated carotid sinus of 30 anesthetized Sprague-Dawley male rats. The results were as follows. (1) By perfusing with ginkgolide B (0.1, 1, 10 µmol/L), the functional curve of the baroreflex was shifted to the right and upward. There was a marked decrease in peak slope (PS) and reflex decrease (RD) in mean arterial pressure (P<0.01), while the threshold pressure (TP), equilibrium pressure (EP) and saturation pressure (SP) were significantly increased (P<0.05, P<0.01). Among the functional parameters of CSB, the changes in PS, RD, TP, EP and SP were dose-dependent. (2) Pretreatment with Bay K8644 (500 nmol/L), an agonist of L-type calcium channel, completely eliminated the effects of ginkgolide B (1 µmol/L) on the CSB. (3) Pretreatment with tetraethylammonium (TEA, 1 mmol/L), an inhibitor of potassium channel, completely abolished the above effects of ginkgolide B (1 µmol/L) on the CSB. These results suggest that ginkgolide B inhibits the CSB in anesthetized rats, which is mediated by decreased calcium influx and increased potassium efflux in baroreceptor nerve endings.

Effect of resveratrol on baroreceptor activity of carotid sinus in anesthetized male rats.

This study is to evaluate the effect of resveratrol on carotid baroreceptor activity (CBA). The functional curve of carotid baroreceptor (FCCB) was constructed and the functional parameters of carotid baroreceptor were measured by recording sinus nerve afferent discharge in anesthetized male rats with perfused isolated carotid sinus. Resveratrol (30, 60 and 120 micromol x L(-1)) inhibited CBA, which shifted FCCB to the right and downward. There was a marked decrease in peak slope (PS) and peak integral value (PIV) of carotid sinus nerve charge in a concentration-dependent manner. Pretreatment with N(omega)-nitro-L-arginine methyl ester (L-NAME, 100 micromol x L(-1)), an inhibitor of nitric oxide synthase (NOS), eliminated the inhibitory effect of resveratrol. Pretreatment with Bay K8644 (an agonist of L-type calcium channel, 500 nmol x L(-1)) abolished the effect of resveratrol on CBA. A potent inhibitor of tyrosine phosphatase (sodium orthovanadate, 1 mmol x L(-1)) did not influence the effect of resveratrol on CBA. Resveratrol inhibits carotid baroreceptor activity, which may be mediated by the locally released NO and decreased calcium influx. Several studies have showed a cardioprotective effect of resveratrol, with the penetrating study of resveratrol, it may show a potential value in the clinical treatment of cardiovascular disease as an alternative medicine.

Hydrogen sulfide facilitates carotid sinus baroreceptor activity in anesthetized male rats.

BACKGROUND: It has been reported that hydrogen sulfide (H(2)S) could relax vascular smooth muscle by direct activation of K(ATP) channels and hyperpolarization of the membrane potential. Recently, our study has shown that H(2)S facilitated carotid baroreflex. This study was conducted to investigate the effect of H(2)S on carotid baroreceptor activity (CBA). METHODS: The functional curve of carotid baroreceptor (FCCB) was constructed and the functional parameters of carotid baroreceptor were measured by recording sinus nerve afferent discharge in anesthetized male rats with perfused isolated carotid sinus. RESULTS: H(2)S (derived from NaHS) 25, 50 and 100 micromol/L facilitated CBA, which shifted FCCB to the left and upward. There was a marked increase in peak slope (PS) and peak integral value of carotid sinus nerve charge (PIV) in a concentration-dependent manner. Pretreatment with glibenclamide (20 micromol/L), a K(ATP) channel blocker, the above effects of H(2)S on CBA were abolished. Pretreatment with Bay K8644 (an agonist of calcium channels, 500 nmol/L) eliminated the role of H(2)S on CBA. An inhibitor of cystathionine gamma-lyase (CSE), DL-propargylglycine (PPG, 200 micromol/L) inhibited CBA in male rats and shifted FCCB to the right and downward. CONCLUSIONS: Our results suggest that exogenous H(2)S exerts a facilitatory role on isolated CBA through opening K(ATP) channels and further closing the calcium channels in vascular smooth muscle. Endogenous H(2)S may activate CBA in vivo.

Electrophysiological effects of hydrogen sulfide on guinea pig papillary muscles in vitro.

The cardiac electrophysiological effects of hydrogen sulfide (H2S) were examined in guinea pig papillary muscles in vitro using intracellular microelectrode technique. The results obtained were as follows: (1) the duration of action potential (APD) in the normal papillary muscles was decreased by NaHS (H(2)S donor, 50, 100, 200 micromol/L) in a concentration-dependent manner; (2) in partially depolarized papillary muscles, 100 micromol/L NaHS not only reduced APD, but also decreased the amplitude of action potential (APA), overshoot (OS) and maximal velocity of depolarization at phase 0 (V(max)); (3) pretreatment with ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide (20 micromol/L) partially blocked the effects of NaHS (100 micromol/L); (4) pretreatment with L-type Ca(2+) channel agonist Bay K8644 (0.5 micromol/L) also partially blocked the effects of NaHS (100 micromol/L); (5) pretreatment with Ca(2+)-free Krebs-Henseleit solution containing glibenclamide (20 micromol/L) completely blocked the effects of NaHS (100 micromol/L); (6) APD in the normal papillary muscles was increased by DL-propargylglycine (PPG, an inhibitor of cystathionine gamma-lyase, 200 micromol/L). All these results suggest that the electrophysiological effects of H(2)S on papillary muscles in our study are due to an increase in potassium efflux through the opening of K(ATP) channels and a decrease in calcium influx. Endogenous H(2)S may act as an important regulator in electrophysiological characters in papillary muscles.