OBJECTIVE: To explore the role of endoplasmic reticulum ryanodine receptor 1 (RyR1) expression and phosphorylation in sepsis- induced diaphragm dysfunction. METHODS: Thirty SPF male SD rats were randomized equally into 5 groups, including a sham-operated group, 3 sepsis model groups observed at 6, 12, or 24 h following cecal ligation and perforation (CLP; CLP-6h, CLP-12h, and CLP-24h groups, respectively), and a CLP-24h group with a single intraperitoneal injection of KN- 93 immediately after the operation (CLP-24h+KN-93 group). At the indicated time points, diaphragm samples were collected for measurement of compound muscle action potential (CMAP), fatigue index of the isolated diaphragm and fitted frequencycontraction curves. The protein expression levels of CaMK Ⅱ, RyR1 and P-RyR1 in the diaphragm were detected using Western blotting. RESULTS: In the rat models of sepsis, the amplitude of diaphragm CMAP decreased and its duration increased with time following CLP, and the changes were the most obvious at 24 h and significantly attenuated by KN-93 treatment (P < 0.05). The diaphragm fatigue index increased progressively following CLP (P < 0.05) irrespective of KN- 93 treatment (P>0.05). The frequency-contraction curve of the diaphragm muscle decreased progressively following CLP, and was significantly lower in CLP-24 h group than in CLP-24 h+KN-93 group (P < 0.05). Compared with that in the sham-operated group, RyR1 expression level in the diaphragm was significantly lowered at 24 h (P < 0.05) but not at 6 or 12 following CLP, irrespective of KN-93 treatment; The expression level of P-RyR1 increased gradually with time after CLP, and was significantly lowered by KN-93 treatment at 24 h following CLP (P < 0.05). The expression level of CaMKⅡ increased significantly at 24 h following CLP, and was obviously lowered by KN-93 treatment (P < 0.05). CONCLUSION Sepsis causes diaphragmatic dysfunction by enhancing CaMK Ⅱ expression and RyR1 receptor phosphorylation in the endoplasmic reticulum of the diaphragm.
Rats ; Male ; Animals ; Diaphragm/metabolism* ; Ryanodine Receptor Calcium Release Channel/metabolism* ; Rats, Sprague-Dawley ; Phosphorylation ; Muscle Contraction/physiology* ; Endoplasmic Reticulum ; Sepsis/metabolism*

Atrial Ca²⁺ handling abnormalities, mainly involving the dysfunction of ryanodine receptor (RyR) and sarcoplasmic reticulum Ca²⁺-ATPase (SERCA), play a role in the pathogenesis of atrial fibrillation (AF). Previously, we found that the expression and function of transient receptor potential vanilloid subtype 4 (TRPV4) are upregulated in a sterile pericarditis (SP) rat model of AF, and oral administration of TRPV4 inhibitor GSK2193874 alleviates AF in this animal model. The aim of this study was to investigate whether oral administration of GSK2193874 could alleviate atrial Ca²⁺ handling abnormalities in SP rats. A SP rat model of AF was established by daubing sterile talcum powder on both atria of Sprague-Dawley (SD) rats after a pericardiotomy, to simulate the pathogenesis of postoperative atrial fibrillation (POAF). On the 3rd postoperative day, Ca²⁺ signals of atria were collected in isolated perfused hearts by optical mapping. Ca²⁺ transient duration (CaD), alternan, and the recovery properties of Ca²⁺ transient (CaT) were quantified and analyzed. GSK2193874 treatment reversed the abnormal prolongation of time to peak (determined mainly by RyR activity) and CaD (determined mainly by SERCA activity), as well as the regional heterogeneity of CaD in SP rats. Furthermore, GSK2193874 treatment relieved alternan in SP rats, and reduced its incidence of discordant alternan (DIS-ALT). More importantly, GSK2193874 treatment prevented the reduction of the S2/S1 CaT ratio (determined mainly by RyR refractoriness) in SP rats, and decreased its regional heterogeneity. Taken together, oral administration of TRPV4 inhibitor alleviates Ca²⁺ handling abnormalities in SP rats primarily by blocking the TRPV4-Ca²⁺-RyR pathway, and thus exerts therapeutic effect on POAF.
Administration, Oral ; Animals ; Atrial Fibrillation/etiology* ; Calcium/metabolism* ; Myocytes, Cardiac/metabolism* ; Pericarditis/pathology* ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel/pharmacology* ; Sarcoplasmic Reticulum/pathology* ; TRPV Cation Channels

OBJECTIVE: To investigate the changes in myocardial calcium currents in rats subjected to forced running exercise during acute hypoxia and their association with myocardial injury. METHODS: Forty SD rats were randomized into quiescent group and running group either in normal oxygen (NQ and NR groups, respectively) or in acute hypoxia (HQ and HR groups, respectively). Hypoxia was induced by keeping the rats in a hypobaric oxygen chamber (PaO₂=61.6kpa) for 4 h a day; the rats in the two running groups were forced to run on running wheels for 4 h each day. Rat ventricular myocytes was isolated by enzymatic digestion for recording action potentials and currents using patch clamp technique, and confocal Ca²⁺ imaging was used to monitor intracellular Ca²⁺ levels. The expressions of Cav1.2 channel and the cardiac ryanodine receptor (RyR2) were determined using Western blotting. RESULTS: Compared with those in NQ group, the rats in HR group showed significantly decreased SOD activity (P < 0.01), increased h-FABP, hs-CRP and IMA levels (P < 0.05 or 0.01), obvious myocardial pathology, and prolonged APD50 and APD90 (P < 0.05). Of the different stress conditions, forced running in acute hypoxia resulted in the most prominent increase of the densities of ICa, L currents, causing also a significant left shift of the steady state activation curve and a significant right shift of the steady state inactivation curve. Compared with those in NQ group, the rats in NR, HQ and HR groups all exhibited higher rates of spontaneous calcium wave events in the cardiac myocytes, increased frequency of calcium sparks with lowered amplitude, enhanced calcium release amplitude in the ventricular myocytes, and delayed calcium ion reabsorption; in particular, these changes were the most conspicuous in HR group (P < 0.05 or 0.01). There was also a significant increase in the protein levels of Cav1.2 channel and RyR2 receptor in HR group (P < 0.05 or 0.01). CONCLUSIONS The mechanism of myocardial injury in rats subjected to forced running in acute hypoxia may involve the increase of oxidative stress and calcium current and intracellular calcium overload.
Animals ; C-Reactive Protein/metabolism* ; Calcium/metabolism* ; Calcium Signaling ; Fatty Acid Binding Protein 3/metabolism* ; Heart Injuries/metabolism* ; Hypoxia/metabolism* ; Myocytes, Cardiac/metabolism* ; Oxygen/metabolism* ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel/metabolism* ; Superoxide Dismutase/metabolism*

OBJECTIVES: To explore the mRNA differential expressions and the sequential change pattern in acute myocardial infarction (AMI) mice. METHODS: The AMI mice relevant dataset GSE4648 was downloaded from Gene Expression Omnibus (GEO). In the dataset, 6 left ventricular myocardial tissue samples were selected at 0.25, 1, 4, 12, 24 and 48 h after operation in AMI group and sham control group, and 6 left ventricular myocardial tissue samples were selected in blank control group, a total of 78 samples were analyzed. Differentially expressed genes (DEGs) were analyzed by R/Bioconductor package limma, functional pathway enrichment analysis was performed by clusterProfiler, protein-protein interaction (PPI) network was constructed by STRING database and Cytoscape software, the key genes were identified by Degree topological algorithm, cluster sequential changes on DEGs were analyzed by Mfuzz. RESULTS: A total of 1 320 DEGs were associated with the development of AMI. Functional enrichment results included cellular catabolic process, regulation of inflammatory response, development of muscle system and vasculature system, cell adhesion and signaling pathways mainly enriched in mitogen-activated protein kinase (MAPK) signaling pathway. The key genes of AMI included MYL7, TSC22D2, HSPA1A, BTG2, NR4A1, RYR2 were up-regulated or down-regulated at 0.25-48 h after the occurrence of AMI. CONCLUSIONS The functional signaling pathway of DEGs and the sequential expression of key genes in AMI may provide a reference for the forensic identification of AMI.
Animals ; Computational Biology/methods* ; Gene Expression Profiling/methods* ; Mice ; Mitogen-Activated Protein Kinases/metabolism* ; Myocardial Infarction/metabolism* ; RNA, Messenger ; Ryanodine Receptor Calcium Release Channel/metabolism* ; Transcriptome

This study aimed to explore the positive inotropic effect of phosphodiesterase type 9 (PDE9) inhibitor PF-04449613 in ratsand its cellular and molecular mechanisms. The heart pressure-volume loop (P-V loop) analysis was used to detect the effects of PF-04449613 on rat left ventricular pressure-volume relationship, aortic pressures and peripheral vessel resistance in healthy rats. The Langendorff perfusion of isolated rat heart was used to explore the effects of PF-04449613 on heart contractility. The cardiomyocyte sarcoplasmic reticulum (SR) Ca
Animals ; Calcium/metabolism* ; Myocardial Contraction ; Myocytes, Cardiac/metabolism* ; Phosphodiesterase Inhibitors ; Phosphoric Diester Hydrolases ; Rats ; Ryanodine Receptor Calcium Release Channel ; Sarcoplasmic Reticulum

This study aimed at constructing a draft genome of the adult female worm Toxocara canis using next-generation sequencing (NGS) and de novo assembly, as well as to find new genes after annotation using functional genomics tools. Using an NGS machine, we produced DNA read data of T. canis. The de novo assembly of the read data was performed using SOAPdenovo. RNA read data were assembled using Trinity. Structural annotation, homology search, functional annotation, classification of protein domains, and KEGG pathway analysis were carried out. Besides them, recently developed tools such as MAKER, PASA, Evidence Modeler, and Blast2GO were used. The scaffold DNA was obtained, the N50 was 108,950 bp, and the overall length was 341,776,187 bp. The N50 of the transcriptome was 940 bp, and its length was 53,046,952 bp. The GC content of the entire genome was 39.3%. The total number of genes was 20,178, and the total number of protein sequences was 22,358. Of the 22,358 protein sequences, 4,992 were newly observed in T. canis. Following proteins previously unknown were found: E3 ubiquitin-protein ligase cbl-b and antigen T-cell receptor, zeta chain for T-cell and B-cell regulation; endoprotease bli-4 for cuticle metabolism; mucin 12Ea and polymorphic mucin variant C6/1/40r2.1 for mucin production; tropomodulin-family protein and ryanodine receptor calcium release channels for muscle movement. We were able to find new hypothetical polypeptides sequences unique to T. canis, and the findings of this study are capable of serving as a basis for extending our biological understanding of T. canis.
Adult ; B-Lymphocytes ; Base Composition ; Classification ; DNA ; Female ; Genome* ; Genomics ; Humans ; Larva Migrans, Visceral* ; Metabolism ; Mucins ; Peptides ; Protein Structure, Tertiary ; Receptors, Antigen, T-Cell ; RNA ; Ryanodine Receptor Calcium Release Channel ; T-Lymphocytes ; Toxocara canis* ; Toxocara* ; Transcriptome ; Ubiquitin-Protein Ligases

The present study attempted to test a novel hypothesis that Ca(2+) sparks play an important role in arterial relaxation induced by tacrolimus. Recorded with confocal laser scanning microscopy, tacrolimus (10 µmol/L) increased the frequency of Ca(2+) sparks, which could be reversed by ryanodine (10 µmol/L). Electrophysiological experiments revealed that tacrolimus (10 µmol/L) increased the large-conductance Ca(2+)-activated K(+) currents (BKCa) in rat aortic vascular smooth muscle cells (AVSMCs), which could be blocked by ryanodine (10 µmol/L). Furthermore, tacrolimus (10 and 50 µmol/L) reduced the contractile force induced by norepinephrine (NE) or KCl in aortic vascular smooth muscle in a concentration-dependent manner, which could be also significantly attenuated by iberiotoxin (100 nmol/L) and ryanodine (10 µmol/L) respectively. In conclusion, tacrolimus could indirectly activate BKCa currents by increasing Ca(2+) sparks released from ryanodine receptors, which inhibited the NE- or KCl-induced contraction in rat aorta.
Animals ; Aorta ; cytology ; metabolism ; physiology ; Calcium Signaling ; Cells, Cultured ; Large-Conductance Calcium-Activated Potassium Channels ; metabolism ; Male ; Muscle, Smooth, Vascular ; drug effects ; metabolism ; physiology ; Myocytes, Smooth Muscle ; drug effects ; metabolism ; Norepinephrine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Ryanodine ; pharmacology ; Tacrolimus ; pharmacology ; Vasoconstriction

OBJECTIVETo investigate changes in adenosine triphosphatase (ATPase) activity and expression of ryanodine receptor 1 (RyR1) mRNA in formation of pressure ulcer at early stage, and to analyze its mechanism.

METHODSThirty-six male Sprague-Dawley rats were divided into three groups according to the random number table as follows, with 12 rats in each group. (1) Ischemia-reperfusion (IR) for 3 times (3IR) group: unilateral gracilis of rats were loaded with 22.47 kPa pressure with a special pressure apparatus for 2.0 h to simulate ischemia, and unloaded for 0.5 h to simulate reperfusion. All rats were treated with above-mentioned manoeuvre for 3 times. (2) IR for 5 times (5IR) group: rats were treated with the same manoeuvre as that in 3IR group except for IR for 5 times. (3) CONTROL GROUP: gracilis of rats were subjected to a load of 0 kPa pressure. Rats in 3IR, 5IR groups were sacrificed, and then central part of pressured tissue was harvested for detection of activity of total ATPase, Ca(2+)-Mg(2+)-ATPase, and Na(+)-K(+)-ATPase with spectrophotometer colorimetry, the level of malondialdehyde (MDA) with enzyme linked immunosorbent assay (ELISA), and the level of RyR1 mRNA with real-time fluorescence quantitative RT-PCR. The same part of gracilis muscle of rats in control group was harvested for determination of indexes as above. Data were processed with one-way analysis of variance. Pearson correlation analysis was respectively performed between total ATPase activity and MDA level, total ATPase activity and RyR1 mRNA expression level, and RyR1 mRNA expression level and MDA level.

RESULTSActivity of total ATPase, Ca(2+)-Mg(2+)-ATPase, Na(+)-K(+)-ATPase in control group was respectively (1.629 ± 0.004), (0.907 ± 0.061), (0.697 ± 0.083) U/mg, all significantly higher than those in 3IR group [(1.365 ± 0.004), (0.784 ± 0.020), (0.581 ± 0.017) U/mg, with F value respectively 1707.0, 29.8, 15.2, P < 0.05 or P < 0.01] and 5IR group [(1.055 ± 0.049), (0.619 ± 0.016), (0.436 ± 0.039) U/mg, with F value respectively 1107.0, 169.9, 65.7, P values all below 0.01], and the values of 3 indexes in 5IR group were obviously lower than those in 3IR group (with F value respectively 322.8, 341.7, 94.0, P values all below 0.01). The level of MDA in control group [(7.5 ± 0.6) nmol/L] was lower than that in 3IR group [(9.9 ± 0.6) nmol/L, F = 53.2, P < 0.01] and 5IR group [(13.7 ± 1.3) nmol/L, F = 76.9, P < 0.01]. There was also statistical difference in MDA level between 3IR group and 5IR group (F = 82.9, P < 0.01). Expression level of RyR1 mRNA in control group (8.5 ± 4.2), which was similar to that in 3IR group (3.3 ± 2.1, F = 0.9, P > 0.05), was significantly higher than that in 5IR group (0.6 ± 0.5, F = 23.6, P < 0.05); while the RyR1 mRNA expression level was lower in 5IR group than in 3IR group (F = 39.3,P < 0.05). Activity of total ATPase was negatively correlated with MDA level (r = -0.918, P < 0.01). Activity of total ATPase was positively correlated with RyR1 mRNA expression level (r = 0.713, P < 0.01). RyR1 mRNA expression level was negatively correlated with MDA level (r = -0.702, P < 0.01).

CONCLUSIONSEnergy dysbolism may be an initial factor in the development of pressure ulcer at early stage. Calcium overload injury in pressure tissue can be identified by determination of RyR1 mRNA expression.

Adenosine Triphosphatases ; metabolism ; Animals ; Male ; Muscle, Skeletal ; metabolism ; Pressure Ulcer ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel ; genetics ; metabolism

OBJECTIVETo explore change of ryanodine receptor (RyR) in junior mouse with heart failure (HF) and the effect of β-adrenoreceptor blocker and Radix astragali on RyR in HF in this experiment.

METHODThe animal model of congestive heart failure was established by coarctation of abdominal aorta. Five weeks old mice were randomly divided into 4 groups: (1) HF group without treatment (n = 30); (2) HF group treated with carvedilol (n = 30); (3) HF group treated with carvedilol and Radix astragali(n = 30); (4) Sham-operated group (n = 30). Carvedilol and Radix astragali were administered through direct gastric gavage. After 4 weeks of treatment the high frequency ultrasound was performed. Myocardial sarcoplasmic reticulum (SR) was fractionated with ultra centrifugation. The time courses of Ca(2+) uptake and leak were determined by fluorescent spectrophotometry. The levels of expression of RyR2 in the 4 groups were detected by semi-quantitative reverse transcription-polymerase chain reaction.

RESULTCompared with the sham-operated group, left ventricular diastolic dimension (LVEDD) (P < 0.05), left ventricular systolic dimension (LVESD), interventricular septal thickness at end-diastole (IVSTd), interventricular septal thickness at end-systole (IVSTs), left ventricular posterior wall thickness at end-diastole (LVPWTd), and left ventricular posterior wall thickness at endsystole (LVPWTs) were all significantly increased (P < 0.01), ejection fraction (EF)(%) (HF group without treatment 51.60 ± 1.15, HF treated with carvedilol 72.06 ± 1.39, HF treated with carvedilol and Radix astragali 79.06 ± 1.09, sham-operated group 85.86 ± 1.45) and fractional shortening (FS) (HF group without treatment 44.55 ± 1.20, HF treated with carvedilol 44.55 ± 1.20, HF treated with carvedilol and Radix astragali 53.58 ± 1.30, sham-operated group 59.03 ± 1.67) were decreased (P < 0.01) in HF group without treatment. LVEDD (P < 0.05), LVESD, IVSTd, IVSTs, LVPWTd and LVPWTs were all significantly decreased (P < 0.01), EF and FS were increased (P < 0.01) in the cases with HF treated with carvedilol and carvedilol and Radix astragali when compared with HF group without treatment. EF and FS were much more increased in the group treated with carvedilol and Radix astragali than in those treated with carvedilol (P < 0.05). After adding thapsigargin to the buffer including SR of the four groups, there were fewer Ca(2+) leak (%) in sham-operated group (11.5 ± 4.3), HF group treated with carvedilol (15.6 ± 5.8) and treated with carvedilol and Radix astragali (13.6 ± 4.8) than that of HF group without treatment (65.6 ± 6.2) (P < 0.01), while after adding FK506 and thapsigargin together to the buffer including SR of four groups, there were marked Ca(2+) leak in sham-operated group (60.6 ± 7.8), HF group treated with carvedilol (66.2 ± 4.5)and those treated with carvedilol and Radix astragali (70.2 ± 5.5, P < 0.01). However, there was no additional increase in Ca(2+) leak in HF group (67.3 ± 7.5) compared with that of the group where only thapsigargin was added (P > 0.05). The levels of expression of RyR2 were significantly decreased in HF group and increased in the group treated with carvedilol and the group treated with carvedilol and Radix astragali.

CONCLUSIONThere was more cardiac Ca(2+) leak and the expression of RyR2 mRNA decreased in HF. Carvedilol and Radix astragali can increase expression of RyR2 mRNA and inhibit Ca(2+) leak by restoring the binding of FKBP12.6 back to RyR in HF to improve cardiac function and prevent left ventricle from remodeling.

Adrenergic beta-Antagonists ; pharmacology ; Animals ; Astragalus Plant ; Carbazoles ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Heart Failure ; metabolism ; Male ; Propanolamines ; pharmacology ; Rats ; Rats, Wistar ; Ryanodine Receptor Calcium Release Channel ; drug effects ; metabolism

Endothelial and neuronal nitric oxide synthases (eNOS and nNOS) are constitutively expressed in cardiomyocytes under the physiological condition, while inducible nitric oxide synthase (iNOS) is only expressed in cell stress. Nitric oxide (NO) derived from the constitutive isoforms of eNOS and nNOS plays four kinds of inhibitory effects on the myocardium: reducing the contractile frequency of cardiomyocyte, slightly attenuating cardiac contractility, accelerating relaxation and increasing distensibility of cardiomyocyte, and slightly inhibiting mitochondrial respiration and improving the efficiency of myocardial oxygen consumption. In conditions of enhanced cardiac reserve and cardiac hypertrophy, NO derived from eNOS, which forms a complex with a certain kind of receptor on the sarcolemma, modulates receptor-mediated signaling and generates an "accentuated antagonism" by moderate inhibition of cardiac contractility. NO derived from the complex of nNOS-ryanodine receptor (RyR) stabilizes RyR calcium release and increases the efficiency of Ca(2+) cycling in sarcoplasmic reticulum by the inhibitory effects. However, besides the above-mentioned inhibitions of NO derived from eNOS and nNOS, NO derived from iNOS generally prevents mitochondrial permeability transition pore opening by inhibiting mitochondrial respiration under the conditions of the myocardial ischemia-reperfusion injury and heart failure. Therefore, both in the physiological condition and in the pathological condition, NO exhibits a moderate inhibition in cardiac function, and eventually produces cardioprotection.
Animals ; Cardiotonic Agents ; Depression, Chemical ; Humans ; Mitochondria, Heart ; metabolism ; Mitochondrial Membrane Transport Proteins ; physiology ; Myocardial Contraction ; physiology ; Myocytes, Cardiac ; enzymology ; Nitric Oxide ; physiology ; Nitric Oxide Synthase ; metabolism ; Oxygen Consumption ; physiology ; Ryanodine Receptor Calcium Release Channel ; physiology