The effects of ketamine on transient outward potassium current (I(to)) of isolated human atrial myocytes were investigated to understand the mechanism of part of its effects by whole-cell patch-clamp. Atrial myocytes were enzymatically isolated from specimens of human atrial appendage obtained from patients under going cardiac valve displacing. Ito is recorded in voltage-clamp modes using the patch-clamp technique at room temperature. Currents signals were recorded by an Axopatch 200B amplifier with the Digidata 1322A-pClamp 9.0 data acquisition system. Ketamine decreased I(to) of human atrial myocytes in a dose-dependent manner. The current-voltage curve was significantly lowered, 30, 100, 300, and 1000 micromol x L(-1) ketamine decreased respectively I(to) current density about (13.62 +/- 0.04)%, (38.92 +/- 0.05)%, (72.24 +/- 0.10)% and (83.84 +/- 0.05)% at the potential of 50 mV, with an IC50 of 121 micromol x L(-1). The I(to) activation curve, inactivation curve and the recovery curve were not altered by ketamine. So, ketamine concentration-dependently decreased I(to) of human atrial myocytes.

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.

OBJECTIVETo investigate the reactivity of intrapulmonary arterial rings to vasoactive substances as thromboxane A2 and endothelin-1 in patients with chronic obstructive pulmonary disease (COPD).

METHODSIntrapulmonary arterial rings isolated from patients with normal lung function and COPD were mounted in a Multi Myograph system to determine the reactivity of the intrapulmonary arterial rings to 60 mmol/L KCl, thromboxane A2 analogue U46619 and endothelin-1 before and after preconditioning with the COX synthase inhibitor indomethacin.

RESULTSThe reactivity of intrapulmonary arterial rings to U46619 and endothelin-1 was significantly decreased in patients with COPD. The reactivity to U46619 was dramatically decreased in patients with normal lung function after application of indomethacin.

CONCLUSIONThe reactivity of intrapulmonary arterial rings is significantly decreased in patients with COPD.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid ; pharmacology ; Aged ; Endothelin-1 ; metabolism ; Female ; Humans ; In Vitro Techniques ; Indomethacin ; pharmacology ; Male ; Middle Aged ; Pulmonary Artery ; metabolism ; Pulmonary Disease, Chronic Obstructive ; metabolism ; Thromboxane A2 ; metabolism

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 .

AIM:To investigate whether the association of connexin 43 ( Cx43 ) and L-type calcium channel involved in the pathogenesis of atrial fibrillation ( AF) .METHODS:The biochemical assays and whole-cell patch-clamp technique were used to study the expression of Cx43 in human atrial tissue.The co-localization of Cx43 and L-type calcium channel, and the regulation of L-type calcium current in atrial myocytes were investigated.RESULTS:The expression of Cx43 at mRNA and protein levels was decreased in human atrial tissues of AF patients.In cultured atrium-derived myocytes ( HL-1 cells) , knockdown of Cx43 significantly inhibited the mRNA expression of L-type calcium channelα1c subunit, as well as L-type calcium current.Co-localization of Cx43 with L-type calcium channel α1c subunit in mouse atrial myocytes was observed.CONCLUSION:The decrease in Cx43 is involved in the pathogenesis of AF, probably through reducing the L-type calcium current in atrial myoctyes by co-localization with L-type calcium channel, thus representing the potential pathogenesis in atrial fibrillation.

Propofol is known to cause vasorelaxation of several systemic vascular beds. However, its effect on the pulmonary vasculature remains controversial. In the present study, we investigated the effects of propofol on human pulmonary arteries obtained from patients who had undergone surgery. Arterial rings were mounted in a Multi-Myograph system for measurement of isometric forces. U46619 was used to induce sustained contraction of the intrapulmonary arteries, and propofol was then applied (in increments from 10–300 µM). Arteries denuded of endothelium, preincubated or not with indomethacin, were used to investigate the effects of propofol on isolated arteries. Propofol exhibited a bifunctional effect on isolated human pulmonary arteries contracted by U46619, evoking constriction at low concentrations (10–100 µM) followed by secondary relaxation (at 100–300 µM). The extent of constriction induced by propofol was higher in an endothelium-denuded group than in an endothelium-intact group. Preincubation with indomethacin abolished constriction and potentiated relaxation. The maximal relaxation was greater in the endothelium-intact than the endothelium-denuded group. Propofol also suppressed CaCl₂-induced constriction in the 60 mM K⁺-containing Ca²⁺-free solution in a dose-dependent manner. Fluorescent imaging of Ca²⁺ using fluo-4 showed that a 10 min incubation with propofol (10–300 µM) inhibited the Ca²⁺ influx into human pulmonary arterial smooth muscle cells induced by a 60 mM K⁺-containing Ca²⁺-free solution. In conclusion, propofol-induced arterial constriction appears to involve prostaglandin production by cyclooxygenase in pulmonary artery smooth muscle cells and the relaxation depends in part on endothelial function, principally on the inhibition of calcium influx through L-type voltage-operated calcium channels.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid ; Arteries ; Calcium ; Calcium Channels ; Constriction ; Endothelium ; Humans* ; Indomethacin ; Myocytes, Smooth Muscle ; Propofol* ; Prostaglandin-Endoperoxide Synthases ; Pulmonary Artery* ; Relaxation ; Vasoconstriction* ; Vasodilation

OBJECTIVETo investigate the effect of dexmedetomidine on 5-HT-induced constrictions of isolated human intrapulmonary arteries and explore the mechanisms.

METHODSLung tissue was obtained from patients undergoing surgery for lung carcinoma. Intrapulmonary arteries were dissected and cut into rings, which were mounted in a Multi Myograph system to determine the effect of dexmedetomidine (0.3-3 nmol/L) on 5-HT-induced vasoconstrictions. The influences of the endothelium removal and various drugs including L-NAME, yohimbine and indomethacin were tested on the effects of dexmedetomidine.

RESULTSDexmedetomidine (0.1-100 nmol/L) did not obviously affect the resting tension of endothelium-intact human intrapulmonary arteries. 5-HT induced concentration-dependent contraction in endothelium-intact intrapulmonary arteries [pD2: 6.11∓0.05, Emax: (102.10∓1.96)%]. In the rings with intact endothelium, dexmedetomidine (0.3-3 nmol/L) significantly attenuated the Emax and pD2 of 5-HT-induced vasoconstriction [pD2: 5.94∓0.03, Emax: (79.96∓1.31)%]. 5-HT also induced concentration-dependent contraction in endothelium-denuded intrapulmonary arteries [pD2: 6.10∓0.07, Emax: (107.40∓3.20)%]. Dexmedetomidine produced no significant effects on the rings with denuded endothelium. The effects of dexmedetomidine on 5-HT-induced vasoconstriction was suppressed by L-NAME and yohimbine, but not by indomethacin.

CONCLUSIONDexmedetomidine can inhibit 5-HT-induced vasoconstriction of isolated human intrapulmonary arteries probably through α2-adrenergic acceptor and NO released from the endothelium.

Adult ; Aged ; Dexmedetomidine ; pharmacology ; Female ; Humans ; In Vitro Techniques ; Male ; Middle Aged ; Pulmonary Artery ; drug effects ; Serotonin ; pharmacology ; Vasoconstriction ; drug effects

Objective To assess the prognosis and effect on renal function of pediatric urolithiasis caused by melamine-contaminated milk powder (PUMMP) in a long-term follow-up.Methods One hundred and two of 8335 children (≤ 6-year-old) with history of consuming melamine-contaminated milk powder screened in our hospital were followed up for eighteen months after diagnosis. Urinary system ultrasonography, urinalysis, urinary microprotein profiles [microalbumin (ALBU), immunoglobulin G (IgG), and N-acetyl-β-D-glucosidase (NAG)], urinary melamine and cyanuric acid were examined in the first visit and at the end of follow-up. Results Follow-up was completed in 91 children and the stone was excreted in 82 children (90.1%).Stones less than 5 mm in diameter were most vulnerable to discharge, and stones larger than 10 mm could not be expelled without interventions. At the end of follow-up, no melamine or cyanuric acid was found in the urine samples of 74 patients. Urinalysis showed that incidences of proteinuria, microscopic hematuria and leukocyturia were 0%, 5.1% and 2.0%, which were significant different from those in the first visit (Pproteinutria=0.123, Phemnatuna=0.038 and Pleukocyhuris=0.005).Urinary microprotein profiles revealed that some children whose urinalysis was normal still presented glomerular and renal tubular injury and the abnormal rates were 8.8% and 12.1%respectively. The glomerular injury was mainly related to persistent stone, male and younger.Conclusions 90.1% of children with PUMMP passes urinary stones at the end of follow-up.Stone size is the major risk factor of discharge. No melamine or cyanuric acid is found in the urine of children. After eighteen months, glomerular and renal tubular injury is still found in some patients. Further follow-up is necessary.

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.
Blotting, Western ; Calcium ; Endoplasmic Reticulum ; Endoplasmic Reticulum Stress ; Endothelial Cells ; Homeostasis ; Human Umbilical Vein Endothelial Cells ; Tunicamycin ; Unfolded Protein Response

AIM:To investigate the influence of fat mass and obesity-associated(Fto)gene on the aberrant contraction of aortic smooth muscle in diabetes mellitus(DM)mice,and to explore the mechanism of Fto gene underlying the calcium regulation.METHODS:Smooth muscle-specific Fto gene knockout(FtoSMKO)mice were generated using Cre-loxP technology.The experiment involved 3 groups of mice:wild-type(WT)group,DM model group and FtoSMKO-DM group,with 15 mice in each group.In DM group and FtoSMKO-DM group,type 1 DM was induced by intraperitoneal injec-tion of streptozotocin.The mice in WT group were injected with equal volume of citric acid-sodium citrate buffer solution.The influences of different drugs on the contraction responses of aortic smooth muscle in mice were analyzed using a multi-myograph system.The expression level of FTO protein in the aortic tissues was detected by Western blot.RESULTS:(1)Compared with WT mice,the expression levels of FTO protein in the aortic tissues of DM mice were significantly in-creased(P＜0.01).(2)The expression level of FTO protein in smooth muscle was significantly decreased after knockout of Fto gene(P＜0.01).Compared with WT group,the mice in DM group exhibited a significant decrease in body weight and a marked increase in fasting blood glucose level(P＜0.05).There were no noticeable differences in body weight or fasting blood glucose level between FtoSMKO-DM group and DM group(P＞0.05).(3)The contraction responses of aortic smooth muscle in DM group were substantially increased by phenylephrine compared with WT group.Specifically,vaso-constriction responses mediated by non-L-type calcium channels and store-operated calcium channels(SOCC)were signifi-cantly enhanced in DM group.In addition,the responses mediated by inositol 1,4,5-trisphosphate receptors(IP3R),which facilitate calcium release from the sarcoplasmic reticulum,were significantly enhanced.However,the responses mediated by caffeine-activated ryanodine receptors(RyR),which also facilitate calcium release from the sarcoplasmic re-ticulum,were significantly inhibited(P＜0.05).(4)Compared with DM group,the phenylephrine-induced contraction re-sponses of aortic smooth muscle in FtoSMKO-DM group were greatly weakened(P＜0.05).In particular,the vasoconstriction responses mediated by non-L-type calcium channels and SOCC in FtoSMKO-DM group were greatly suppressed(P＜0.05),while those mediated by caffeine-activated RyR were dramatically boosted(P＜0.05).However,IP3R-mediated responses were not affected(P＞0.05).CONCLUSION:Smooth muscle-specific Fto gene knockout suppresses contractile hyperre-sponsiveness in the aortic smooth muscle of DM mice,which may be attributed to involvement of FTO protein in calcium regulation in the vascular smooth muscle.