METTL3-mediated m6A modification involved in electrical remodeling of atrial cardiomyocytes under high hydrostatic pressure / 中国药理学通报

To investigate the regulation of N6- methyladenosine ( m6A ) modification on L-type calcium channels in atrial myocytes under high hydrostatic pressure, mediated by methyltransferase-like protein 3 ( METTL3 ). Methods C57BL/6J mice were randomly assigned to the control group and the hypertension group ( treated with continuous administration of angiotensin for four weeks ). Masson staining was used to observe the fibrosis of mouse atrial tissue, while dot blot assay and Western blot were used to detect the levels of m6A, METTL3, and Cavi1 2 in the atrial tissue. A high hydrostatic pressure model was constructed using the HL-1 cell line cultured in vitro, and METTL3 was intervened to observe changes in m6A expression levels, METTL3 and Cavi1 2 levels in cells,and action potential duration ( APD ) and L-type calcium current ( I

Mechanosensitive ion channel Piezo1 induces senescence of atrial fibroblasts by activating β-catenin / 中国药理学通报

Aim To observe whether the mechanosensitive ion channel Piezo1 was involved in the senescence of atrial fibroblasts by activating β-catenin based on our previous study which found marked increase of Piezo1 mRNA in senescent atrial fibroblasts. Methods Primary mouse atrial fibroblasts (MAFs) were isolated from male C57BL/6 mice (3-4 weeks) by enzyme digestion, and tert-butyl hydroperoxide (TBHP) was used to induce the senescence of cells. The ratio of senescent cells was detected by senescence-associated β-galactosidase (SA-β-Gal) staining. The protein levels of Piezo1, β-catenin/p-β-catenin, senescence-associated proteins p53 and p21 in the cells treated with TBHP (100 μmol · L

Rho A/ROCK signaling pathway involved in hyper responsiveness to aortic contraction in mice with type 2 diabetes / 中国药理学通报

Aim To investigate the mechanism of RhoA/ROCK signaling pathway in abnormal aortic contractility in type 2 diabetes (T2DM) mice. Methods The experiment was divided into two groups, the control group (db/m mice) and the model group (db/db mice). Changes of the response to different methods were measured in aorta rings using a Multi Myograph System. At the same time, the protein expression changes of aortic smooth muscle contraction signaling pathway in mice were determined by Western method. Results Compared with the control group, the blood glucose and body weight levels of the mice in the T2DM group significantly increased, and the cardiac function was abnormal (P <0. 01). The contractile response of the aorta of the diabetic mice induced by the contractile agents Phe, 5-HT and CaCl

Role of calcium-independent phospholipase A2 in contraction of intrarenal artery smooth muscle / 中国药理学通报

Aim To investigate the role of calcium-independent phospholipase A2(iPLA2)in calcium regu-lation of intrarenal artery smooth muscle contraction.Methods The method of measuring the tension of isolated arterioles was used to explore the effect of bromoenol lactone(BEL), a specific inhibitor of iPLA2, on the tension of the intrarenal arteries in mice induced by different calcium channels, and the laser confocal calcium measurement technology was used to investigate the effect of BEL on the intracellular calcium influx mediated by arachidonic acid-mediated calcium channels.Results The intrarenal artery concentration dependent contractile response induced by the vasoconstrictors phenylephrine and 5-hydroxy tryptamine was inhibited by BEL(P<0.01).The contraction curve induced by CaCl2 was also inhibited by BEL(P<0.05).In the calcium-free K-H solution incubated with nifedipine, the intrarenal artery vasoconstriction caused by the release of sarcoplasmic reticulum calcium and the calcium influx of the SOC channel induced by CaCl2 was inhibited by BEL(P<0.05).BEL significantly inhibited the external calcium influx mediated by the ARC channel of human aortic smooth muscle cell lines incubated with nifedipine(P<0.01).Conclusions iPLA2 mediates the contractile response of intrarenal arteries by regulating the functions of L-type calcium channels, sarcoplasmic reticulum calcium release, SOC channels and ARC channels.

Piezol involved in electrical remodeling in atrial myocytes induced by high hydrostatic pressure through Src kinase / 中国药理学通报

Aim To investigate the role of mechano- sensitive ion channel Piezol in regulating electrical re-modeling of atrial myocytes induced by hypertension and to further explore the potential mechanisms.Methods Spontaneously hypertensive rats ( SHR ) aged 30 - 32 weeks treated with or without valsartan (30 mg • kg 1 • d 1 ) were used.Wistar rats were used as control.Western blot was used to detect the protein expression of Piezol , Src and Cavl.2 in atrial appendages of rats and in atrial myocytes ( HL-1 cells) exposed to different levels of high hydrostatic pressure (20 and 40 mmHg) , Piezol inhibitor (GsmTx4) and agonist ( Yodal ) in vitro.Whole-cell patch clamp technique was employed to detect L-tvpe calcium current (ICa, ) and action potential duration ( APD) of atrial myocytes.Results Compared with Wistar rats in control group, the protein expressions of Piezol and Src significantly increased and the expression of Cavl.2 decreased in SHR group (P < 0.05 ), while the a- bove changes could he reversed in SHR treated with valsartan( P < 0.05 ) .Meanwhile, higher hydrostatic pressure (40 mniHg) could increase the expressions of Piezol and Src in HL-1 cells( P <0.05) and decrease the protein expression of Cavl.2 (P <0.05 ) , accompanied by a shortened APD and a decreased ICa,.GsmTx4 could significantly reverse the above changes.In addition, Piezol agonist Yodal could simulate electrical remodeling and related signal molecule changes in atrial myocytes induced by the high hydrostatic pressure.Conclusions Mechanosensitive ion channel Piezol participates in electrical remodeling induced by hypertension via activating Src kinase signaling pathway and then leading to the decrease of ICa ,.

Role of mechanosensitive ion channel Piezol in mediating phenotypic changes of rat coronary arterial smooth muscle cells induced by high hydrostatic pressure / 中国药理学通报

Aim To investigate the mechanism of Pi- ezol in the phenotypic changes of rat coronary arterial smooth muscle cells ( CASMCs) induced by high hydrostatic pressure.Methods CASMCs were isolated from Wistar rats and stimulated for 24 h at 0, 120 and 180 mmHg, respectively.The expressions of Piezol , contractile phenotvpe-related proteins including Cavl.2 ,SM-MHC ,cx-SMA and synthetic phenotvpe-re- lated proteins including OPN , MMP-2, Coll al were detected by Western blot.The effect of calcium influx mediated by Piezol was detected by Laser confocal mi- j j croscopy.CASMCs were treated with Piezol agonist Yodal , inhibitor GsMTx4 and Piezol-siHNA , respectively and the expressions of contractile phenotvpe and synthetic phenotvpe-related proteins were detected by Western blot.Results Compared with control ( 0 mmHg) , the expressions of Piezol , OPN, MMP-2 and Collal increased, but the expressions of Cavl.2,SM- MHC and cx-SMA decreased in 120 mmHg as well as 180 mmHg group.After stimulated by 180 mmHg high pressure, Piezol-mediated calcium influx was stronger than that in 0 mmHg group, hut decreased after Piezol knockdown.Treated with Yodal at 0 mmHg, the expression of contractile phenotvpe-related protein decreased while the expression of synthetic phenotvpe-re- lated protein increased compared with DMSO group..\Jfter using GsMTx4 to inhibit or siRNA to knockdown Piezol at 180 mmHg,the expression of contractile phe- notvpe-related protein increased and the expression of synthetic phenotype-related protein decreased compared with the control group.Conclusion Piezol promotes the transition from contractile phenotvpe to syn-thetic phenotvpe of CASMCs induced by high hydrostatic pressure.

Role of DNA dioxygenase TET1 in cardiac fibrosis induced by high pressure / 中国药理学通报

Aim To investigate the mechanism of TET1 in cardiac fibrosis induced by high pressure. Methods Wistar rats and spontaneous hypertension rats(SHR) were selected to detected the expression of TET1, TGF-β, COL-1 and COL-3 in myocardium by Western blot; HE and Masson staining were used to detect myocardial pathological changes. Neonatal rat cardiac fibroblasts (NRCFs) were isolated from the ventricles of neonatal Sprague-Dawley rats and stimulated by 0 mm-Hg, 120 mmHg and 180 mmHg high pressure. Immunofluorescence was used to detect the changes of 5-hmC in the NRCFs. The changes of 5-hmC and 5-mC in TGF-β promoter region were detected by qRT-PCR. The expressions of TET1, TGF-β, COL-1 and COL-3 were detected by Western blot. Results Compared with Wistar rats, SHR showed increased blood pressure, increased fibrous collagen in ventricular tissues, and significantly increased expressions of TET1, TGF-P, COL-1 and COL-3. Compared with the 0 mmHg group, 120 mmHg and 180 mmHg group significantly induced the increase of TET1, 5-hmC, TGF-p, COL-1 and COL-3. TET1 knockdown significantly reduced the increase of 5-hmC, TGF-β, COL-1 and COL-3 under 180 mmHg pressure. Besides, knockdown TET1 significantly reduced the level of 5-hmC and increased the level of 5-mC and 5-hmC in the TGF-β promoter region. Conclusions High pressure induced cardiac fibrosis is associated with the promotion of TGF-β promoter demethylation and the increased of TGF-β expression by TET1.

Sacubitril/valsartan reduces susceptibility of atrial fibrillation by reversing structural remodeling of atrial in spontaneously hypertensive rats / 中国药理学通报

Aim To observe the effects of sacubitril/valsartan (Sac/Val, LCZ696) on atrial remodeling and atrial fibrillation (AF) susceptibility in spontaneously hypertensive rats (SHR). Methods Twenty-four 7-week-old male SHR were randomly divided into SHR group, SHR + Val group (30 mg · kg

Role of Ca / 中国药理学通报

Aim To investigate the role of Ca

Transcriptional co-activator p300 participates in atrial fibrosis induced by high hydrostatic pressure by regulating TGF-β/Smad3 signaling pathway / 中国药理学通报

Aim To investigate the role and potential mechanism of transcriptional co-activator p300 in atrial fibrosis caused by high hydrostatic pressure. Methods The left atrial appendage tissues of humans in three groups of sinus rhythm, atrial fibrillation (AF), hypertension and AF were collected. The expressions of p300 protein and TGF-β/Smad3 signaling pathway and fibrotic factors as type I/III collagen Alphal chain (Col-lAl/Col-3Al), matrix metalloproteinase 2/9 (MMP-2/9) were tested by Western blot. Mouse atrial appendage fibroblasts were cultured under hydrostatic pressures of 0, 20 and 40 mmHg. The fibroblasts cultured under 40 mmHg pressure were treated with curcumin and p300 interference RNA. Western blot was used to test changes in the expression of p300 and the above fibrosis indicators. CCK-8 method was used to test changes of cell proliferation. Results The expressions of p300 and TGF-β/Smad3 signaling pathway proteins and fibrotic factors in AF group and hypertension combined with AF group were significantly higher than those in sinus rhythm group (P < 0. 05). 40 mmHg high hydrostatic pressure stimulation in vitro could increase the expression of p300 and fibrotic factors in fibroblasts (P < 0. 0 5) and enhance the proliferation ability (P < 0. 05). Both curcumin and p300 interfering RNA could reverse the increased expression of p300 and fibrotic factors (P < 0. 05) and decrease cell proliferation (P < 0. 05) induced by hydrostatic pressure. Conclusions High hydrostatic pressure can induce atrial fibrosis, which involves the participation of p300 in this process by regulating the TGF-β/Smad3 signaling pathway.

Role of p300 in susceptibility of atrial Hbrillation in aged mice / 中国药理学通报

Aim To explore the role of cotranscriptional activator p300 in regulating the electrical remodeling of atrial myocytes in aging mouse, which resulted in atrial fibrillation. Methods The left atrial appendage tissues of 5 , 13 and 18monthold C57BL/6 mice were collected respectively. Western blot was used to detect the protein expression levels of p300, L type calcium channel (Cavl. 2) and aging related protein p53/p21. Acute enzymatic hydrolysis was used to isolate single atrial myocytes, and the wholecell patchclamp technique was used to detect the Ltype calcium current (I

The electrophysiological remodeling of atrial myocytes of type 1 diabetic mice and effects of AGE / 中国药理学通报

Aim To explore type 1 diabetes mice and the advance glycation end products (AGE) involved in electrical remodeling of atrial myocytes. Methods The diabetic mouse model was induced by intraperitoneal injection of STZ; action potential duration, and the current density of I

Involvement of Src kinase in the down-regulation of ultra-rapid delayed rectifier K(+)current induced by tumor necrosis factor-α in cardiomyocytes / 中华心血管病杂志

Objective: To investigate whether inflammatory factor tumor necrosis factor-α (TNF-α) is involved in the electrical remodeling of cardiomyocytes by regulating ultra-rapid delayed rectifier K(+) current (I(kur)) and the role of Src kinase. Methods: H9c2 cells, embryonic cardiomyocytes of rat, were cultured in Dulbecco's modified Eagle's medium (DMEM) and atrium-derived HL-1 cells were cultured in Claycomb medium. Both H9c2 and HL-1 cells were cultured at 37 ℃ with 5% CO(2). Cells cultured in normal conditions without additional treatment served as control group. Experimental groups were treated with different concentration of TNF-α (25 or 50 or 100 ng/ml) for 24 hours. To study whether Src specific inhibitor PP1 could abrogate the effect of TNF-α, cells were pre-treated with 10 μmol/L PP1 for 1 hour, followed by TNF-α (100 ng/ml) for 24 hours. Western blot and the whole cell patch clamp technique were used to detect the protein expression of Kv1.5 and Src and I(kur) in each group. Results: (1) In H9c2 cells, high concentration of TNF-α treatment (100 ng/ml) significantly reduced the Kv1.5 protein expression compared with control group and TNF-α 25 ng/ml group (both P<0.05). Compared with control group, the expression of p-Src protein was higher in 25 ng/ml, 50 ng/ml, 100 ng/ml TNF-α group (all P<0.05), but there was no statistical difference in the expression of Src protein among groups (P>0.05). In addition, the current density of I(kur) was decreased in 50 ng/ml, 100 ng/ml TNF-α group (both P<0.05). Furthermore, the expression of Kv1.5 protein and the current density of I(kur) were increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (both P<0.05). There was no statistical difference in the expression of Kv1.5 protein and the current density of I(kur) between the control group and PP1+TNF-α group (both P>0.05). (2) In atrium-derived HL-1 cells, the expression of Kv1.5 protein was reduced in 100 ng/ml TNF-α group compared with control group and TNF-α 25 ng/ml group (both P<0.01). In addition, the expression of p-Src protein was increased in TNF-α 100 ng/ml group compared with control group (P<0.05), but there was no statistical difference in the protein expression of Src among groups (P>0.05). The expression of Kv1.5 protein was increased in PP1+TNF-α group compared with TNF-α 100 ng/ml group (P<0.05). Conclusion: TNF-α is involved in the pathogenesis of atrial fibrillation, probably via decreasing I(kur) current density in atrium-derived myocytes through the activation of Src kinase.

Involvement of Orai1 in tunicamycin-induced endothelial dysfunction

Endoplasmic reticulum (ER) stress is mediated by disturbance of Ca²⁺ homeostasis. The store-operated calcium (SOC) channel is the primary Ca²⁺ channel in non-excitable cells, but its participation in agent-induced ER stress is not clear. In this study, the effects of tunicamycin on Ca²⁺ influx in human umbilical vein endothelial cells (HUVECs) were observed with the fluorescent probe Fluo-4 AM. The effect of tunicamycin on the expression of the unfolded protein response (UPR)-related proteins BiP and CHOP was assayed by western blotting with or without inhibition of Orai1. Tunicamycin induced endothelial dysfunction by activating ER stress. Orai1 expression and the influx of extracellular Ca²⁺ in HUVECs were both upregulated during ER stress. The SOC channel inhibitor SKF96365 reversed tunicamycin-induced endothelial cell dysfunction by inhibiting ER stress. Regulation of tunicamycin-induced ER stress by Orai1 indicates that modification of Orai1 activity may have therapeutic value for conditions with ER stress-induced endothelial dysfunction.

Mechanism of coronary artery constriction induced by 5-HT / 中国病理生理杂志

AIM:To investigate the possible mechanism of coronary artery contraction induced by 5-hydroxytryptamine(5-HT).METHODS:Isolated coronary artery rings were obtained from male Wistar rats,and the vas-cular tension meter was used to determine the tension of the coronary artery rings.The effects of inhibitors of different sig-naling pathway on vascular contraction tension induced by 5-HT were observed.RESULTS:Firstly,we found that 5-HT2A receptor antagonist sarpogrelate(1 μmol/L)completely eliminated the coronary artery contraction induced by 5-HT.Phos-pholipase Cβ(PLCβ)inhibitor U73122(10 μmol/L and 50 μmol/L), Rho-related protein kinase inhibitor Y-27632(3 μmol/L and 10 μmol/L)and protein kinase C δ subunit(PKCδ)inhibitor rottlerin(3 μmol/L and 10 μmol/L)signifi-cantly inhibited the contraction of coronary artery ring caused by 5-HT(P<0.05).In addition, compared with the un-treated group,vascular contraction tension induced by 5-HT was also decreased significantly by L-type calcium channel (Cav1.2)blocker nifedipine(1 μmol/L), store-operated Ca2+entry(SOCE)inhibitor SKF96365(10 μmol/L and 30 μmol/L)and 2-aminoethoxydiphenyl borate(2-APB,50 μmol/L and 100 μmol/L)(P<0.05).At the same time,5-HT also induced vasoconstriction after treated with nifedipine(1 μmol/L)Kerbs-Henseleit(K-H)liquid without calcium (P<0.05).CONCLUSION:5-HT activates 5-HT2Areceptor induced coronary artery contraction,possibly related to the PKC/Rho kinase signaling pathway and calcium regulation.

Changes of cardiac function, RAGE expression and calcium dysregula-tion in type 2 diabetic rats / 中国病理生理杂志

AIM:To investigate the changes of cardiac structure and function in rats with type 2 diabetic melli-tus(T2DM),and to explore the mechanisms underlying diabetic cardiomyopathy.METHODS:The cardiac structure and function were measured by echocardiography in Zucker diabetic fatty(ZDF)rats and their control Zucker lean(ZL)rats. The size of the cardiomyocytes was determined by wheat germ agglutinin staining.The protein expression of atrial natriuretic peptide(ANP),β-myosin heavy chain(β-MHC), receptor for advanced glycation end products(RAGE), L-type cal-cium channel α1C subunit(CaV1.2)and Orai1 was assessed by Western blot.RESULTS:Compared with the ZL control rats,the thickness of left ventricular wall,ejection fraction(EF),fractional shortening(FS)and the sizes of cardiomyo-cytes were significantly increased,and diastolic function was decreased in the ZDF rats(P<0.05).The protein expression of β-MHC, ANP, RAGE and Orai1 was increased, while the expression of Ca V1.2 was decreased in ZDF rats(P <0.05).CONCLUSION:T2DM rats show the prominent features including cardiomyocyte hypertrophy,ventricular hyper-trophy and compensatory enhancement of cardiac function, and the Ca2+handling and increase in RAGE expression may play important roles in the processes.

L-type calcium channel involved in heterogeneity of arterial constriction in different organs of rats / 中国药理学通报

Aim To study whether there was arterial heterogeneity and association with L-type calcium channel (LCC) in different parts of arteries in re-sponse to certain vasoconstrictor. Methods The aor-ta, renal arteries and coronary arteries were dissected from rats. Arterial ring contractions induced by pheny-lephrine (Phe), 5-hydroxyl tryptamine (5-HT) or U46619 in concentration-dependent manner were meas-ured using the Multi Myograph system and the response to nifedipne was observed. Results (1) Phe had no obvious effect on the tension of coronary artery,but in-duced concentration-dependent vasoconstriction in aor-ta and renal artery,and pEC50of aorta was significantly higher than that of renal artery (P<0.05). The inhi-bition rate of nifedipine on the aortic contractile re-sponses was significantly higher than that of renal arter-y (P<0.05). (2) The contraction induced by 5-HT on aorta was not obvious, but was significant on renal artery and coronary artery. The inhibitory rate of nife-dipine on coronary artery vasoconstriction was signifi-cantly higher than that of renal artery (P <0.05). (3) U46619 could induce aorta,renal artery and coro-nary artery concentration- dependent contraction, but the Emaxof them were both higher than that of renal ar-tery (P<0.05). And the pEC50of aorta was the lar-gest (P<0.05). Nifedipine significantly inhibited the contraction of aorta, renal artery and coronary artery induced by U46619 with the greatest inhibitory rate on the coronary artery vasoconstriction and minimal inhibi-tion on aortic vasoconstriction. Conclusions The re-sponse to certain vasoconstrictor is different among aor-ta, renal artery and coronary artery in rats, and the contraction mediated by L-type calcium channel is also different.

Model construction of rat coronary artery smooth muscle cell endoplas-mic reticulum stress induced by thapsigargin / 中国病理生理杂志

AIM: To investigate the primary culture method for coronary artery smooth muscle cells (CASMCs), and to establish the endoplasmic reticulum stress ( ERS) model in CASMCs of SD rats.METHODS:CASMCs were cultured by tissue explant method .The morphological characteristics were observed under optical micro-scope.The marker proteins of CASMCs , including α-SMA and SM-MHC, were identified by immunofluorescence tech-nique.The protein expression levels of BiP and CHOP , the marker molecules of ERS, were determined by Western blot . RESULTS:The spindle-shaped CASMCs climbed out from the edge of coronary artery tissues after 6 d, and formed the typical hill and valleygrowth pattern of CASMCs at 9~10 d.The result of immunofluorescence technique showed that α-SMA and SM-MHC were positively expressed .The results of Western blot showed that the protein expression of BiP and CHOP in TG ( 1 and 2 μmol/L ) treatment groups was increased compared with control group .Compared with control group, the protein expression of BiP and CHOP was significantly increased after 1 μmol/L TG treatment for 24 and 48 h. CONCLUSION:CASMCs can be successfully cultured by tissue explant method .ERS model of CASMCs was established by 1 μmol/L TG treatment for 24 h.

Effect of circRNA_000203 on fibrotic phenotypes in mouse cardiac fibro-blasts / 中国病理生理杂志

AIM:To determine circular RNA (circRNA) profiles in the diabetic mouse myocardium , and to investigate the effect of circRNA_000203 on fibrotic phenotypes in cardiac fibroblasts .METHODS:Masson trichrome stai-ning was performed on the myocardium of the diabetic db /db mice and the non diabetic db/m control mice .circRNA ex-pression profile in the diabetic myocardium was detected by circRNAs microarray .The expression of circRNA_000203 was determined by real time fluorescence quantitative PCR ( RT-qPCR ) .Recombinant circRNA_000203 adenovirus was pre-pared for enforced the expression of circRNA_000203 in mouse cardiac fibroblasts.The expression of Col1a2, Col3a1andα-SMA was determined in circRNA_000203-modified cardiac fibroblasts , respectively .RESULTS:Masson trichrome stai-ning showed that fibrosis was increased in the diabetic mouse myocardium .The results of circRNA array detection revealed that circRNAs were dysregulated in the diabetic myocardium .circRNA_000203 was up-regulated in the diabetic myocardi-um.Significant over-expression of circRNA_000203 was achieved in the cardiac fibroblasts after infection with the recombi-nant circRNA_000203 adenovirus.The mRNA and protein expression of Col1a2, Col3a1 and α-SMA was significantly in-creased in the cardiac fibroblasts with over-expression of circRNA_000203.CONCLUSION:circRNA_000203 is up-regu-lated in the diabetic mouse myocardium .It has pro-fibrotic effect on the cardiac fibroblasts .

Role of tumor necrosis factor-αin the regulation of T-type calcium channel current in HL-1 cells / 中国病理生理杂志

AIM:Increasing evidence indicates that inflammation contributes to the initiation and perpetuation of atrial fibrillation ( AF) .Al-though tumor necrosis factor ( TNF)-αlevels are increased in patients with AF , the role of TNF-αin the pathogenesis of AF remains unclear.Recent research has revealed that T-type Ca2+currents ( ICa,T ) play an important role in the pathogenesis of AF .METH-ODS:In this study , we used the whole-cell voltage-clamp technique and biochemical assays to explore the role of TNF-αin the regula-tion of ICa,T in atrial myocytes.RESULTS:We found that compared with sinus rhythm (SR) controls, T-type calcium channel (TCC) subunit mRNA levels were decreased , while TNF-αexpression levels were increased , in human atrial tissue from patients with AF .In murine atrial myocyte HL-1 cells, after cultured for 24 h, 12.5, 25 and 50 μg/L TNF-αsignificantly reduced the protein expression levels of the TCC α1G subunit in a concentration-dependent manner .The peak current was reduced by the application of 12.5 or 25μg/L TNF-αin a concentration-dependent manner [from ( -15.08 ±1.11) pA/pF in controls to ( -11.89 ±0.83) pA/pF and (-8.54 ±1.55) pA/pF in 12.5 and 25 μg/L TNF-αgroups, respectively].TNF-αapplication also inhibited voltage-dependent inactivation of ICa,T shifted the inactivation curve to the left .CONCLUSION:These results suggest that TNF-αis involved in the path-ogenesis of AF, probably via decreasing ICa,T function in atrium-derived myocytes through impaired channel function and down -regula-tion of channel protein expression .This pathway thus represents a potential pathogenic mechanism in AF .