Lowered expression of CCN5 in endometriotic tissues promotes proliferation, migration and invasion of endometrial stromal cells / 南方医科大学学报

OBJECTIVE@#To explore the expression of CCN5 in endometriotic tissues and its impact on proliferation, migration and invasion of human endometrial stromal cells (HESCs).@*METHODS@#We collected ovarian endometriosis samples from 20 women receiving laparoscopic surgery and eutopic endometrium samples from 15 women undergoing IVF-ET for comparison of CCN5 expression. Cultured HESCs were transfected with a recombinant adenovirus Ad-CCN5 for CCN5 overexpression or with a CCN5-specific siRNA for knocking down CCN5 expression, and the changes of cell proliferation, migration and invasion were evaluated using CCK-8 assay, wound healing assay and Transwell chamber assay. RT-qPCR and Western blotting were used to examine the expression levels of epithelial-mesenchymal transition (EMT) markers including E-cadherin, N-cadherin, Snail-1 and vimentin in HESCs with CCN5 overexpression or knockdown.@*RESULTS@#CCN5 expression was significantly decreased in ovarian endometriosis tissues as compared with eutopic endometrium samples (P < 0.01). CCN5 overexpression obviously inhibited the proliferation, migration and invasion of HESCs, significantly increased the expression of E-cadherin and decreased the expressions of N-cadherin, Snail-1 and vimentin (P < 0.01). CCN5 knockdown significantly enhanced the proliferation, migration and invasion of HESCs and produced opposite effects on the expressions of E-cadherin, N-cadherin, Snail-1 and vimentin (P < 0.01).@*CONCLUSION@#CCN5 can regulate the proliferation, migration and invasion of HESCs and thus plays an important role in EMT of HESCs, suggesting the potential of CCN5 as a therapeutic target for endometriosis.

Current situation and influence factors of suicidal self-injurious behavior in teenagers in Guangdong / 上海预防医学

Objective:To investigate the current situation of suicidal self-injurious behavior in teenagers and analyze its influencing factors. Methods:From January to November 2020， a stratified sampling method was used to investigate 707 teenagers in Guangdong. The “questionnaire of health-related behaviors of Chinese teenagers” compiled by the Chinese Center for Disease Control and Prevention was used anonymously to investigate the current situation of suicidal self-injurious behavior of the teenagers. The chi-square test was used for univariate analysis， and logistic regression was used for multivariate analysis. Results:The incidence rate of suicidal self-injurious behavior was 14.57% （103/707）. It was 13.31% （45/338） in males， 15.72% （58/369） in females， 13.83% （48/347） in junior high school students and 15.28% （55/360） in senior high school students. There was no statistical significance in the incidence of suicidal self-injurious behavior of teenagers between different genders， different learning stages， smoking or not， asexual behavior or not， gambling or not， and fighting or not （all P>0.05）. The incidence of suicidal self-injurious behaviors in teenagers from single parent family， drunkenness， runaway， loneliness， under great study pressure， lovelorn， and mobile phone addiction was significantly higher （χ2=13.809， 10.852， 14.279， 11.451， 12.893， 22.905， 19.473， respectively. All P<0.001）. Logistic regression analysis showed that the following were main risk factors affecting the incidence of suicidal self-injurious behavior in teenagers： single parent family （OR=3.826， 95%CI： 1.402-7.501）， drunkenness （OR=3.903， 95%CI： 1.512-7.368）， runaway （OR=3.447， 95%CI： 1.669-7.715）， loneliness （OR=3.613， 95%CI： 1.504-7.697）， great study pressure （OR=3.712， 95%CI： 1.387-7.604）， lovelorn（OR=4.125， 95%CI： 1.516-8.117） and mobile phone addiction（OR=4.027， 95%CI： 1.499-7.984 （all P<0.001）. Conclusion:The incidence of suicidal self-injurious behavior in teenagers is not low in Guangdong， and targeted measures should be developed to screen and intervene based on the influencing factors.

Expression of Tip60（KAT5）in Oral Squamous Cell Carcinoma and Their Correlation / 中山大学学报(医学科学版)

@#【Objective】To study the expression of Tip60（KAT5）in Oral squamous cell carcinoma（OSCC），and to investigate the relationship of Tip60（KAT5）and OSCC.【Methods】Forty-nine samples of OSCC and 36 samples of nor⁃ mal tissue adjacent to OSCC were collected and analyzed retrospectively. The expression of Tip60（KAT5）was detected by immunehisto chemistry using Envision detection system. OSCC cell line Cal27 and UM1 cultured in vitro were treated with Nu9056，an inhibitor of Tip60（KAT5）for 24h，respectively. Then the effect of different concentrations and times on the growth of Cal27 and UM1 cells was evaluated with MTT assay.【Results】The expression of Tip60（KAT5）in OSCC was significantly higher than that in normal tissue adjacent to OSCC（P=0.000）. Its expression was significantly positively correlated with the degree of histological differentiation（r=0.461，P=0.001）. With the increase of concentration，the proliferation inhibition rate of Nu9056 on Cal27 and UM1 cells gradually increased，showing a concentration- dependent and time-dependent relationship（P<0.05）.【Conclusions】The expression of Tip60（KAT5）protein in oral squamous cell carcinoma tissues was related to the degree of histological differentiation ，Tip60（KAT5）can be used as oral squamous cell carcinoma progression and prognosis of biological indicators.

Angiotensin-Converting Enzyme 2 in the Rostral Ventrolateral Medulla Regulates Cholinergic Signaling and Cardiovascular and Sympathetic Responses in Hypertensive Rats / 神经科学通报·英文版

The rostral ventrolateral medulla (RVLM) is a key region in cardiovascular regulation. It has been demonstrated that cholinergic synaptic transmission in the RVLM is enhanced in hypertensive rats. Angiotensin-converting enzyme 2 (ACE2) in the brain plays beneficial roles in cardiovascular function in hypertension. The purpose of this study was to determine the effect of ACE2 overexpression in the RVLM on cholinergic synaptic transmission in spontaneously hypertensive rats (SHRs). Four weeks after injecting lentiviral particles containing enhanced green fluorescent protein and ACE2 bilaterally into the RVLM, the blood pressure and heart rate were notably decreased. ACE2 overexpression significantly reduced the concentration of acetylcholine in microdialysis fluid from the RVLM and blunted the decrease in blood pressure evoked by bilateral injection of atropine into the RVLM in SHRs. In conclusion, we suggest that ACE2 overexpression in the RVLM attenuates the enhanced cholinergic synaptic transmission in SHRs.

Correlation between fasting C-peptide and serum uric acid in patients with type 2 diabetes mellitus / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the relationship between fasting C-peptide (F-CP) and serum uric acid (SUA) in patients with type 2 diabetes mellitus (T2DM).</p><p><b>METHODS</b>A total of 347 hospitalized patients with T2DM were stratified according to F-CP level to analyze the impact of increased F-CP levels on SUA level and the incidence of hyperuricemia (HUA). The patients with an elevated SUA level (>420 µmol/L) and a normal SUA level (≤420 µmol/L) were compared for general data, fasting C-peptide and other clinical indexes. Pearson or Spearman correlation analysis was used to analyze the correlation of SUA level with F-CP levels and other parameters. The risk factors of elevated SUA were analyzed by binary logistic regression, multiple regression analysis and hierarchical interaction analysis. The ROC curve was used to analyze the independent risk factors of elevated SUA and determine the corresponding cut-off values.</p><p><b>RESULTS</b>Compared with those with a normal SUA level, patients with elevated SUA had higher body mass index (BMI), waist-to-hip ratio, F-CP, postprandial 2hC peptide (2hP-CP), triglyceride (TG), homocysteine (HCY), serum creatinine (SCr) level (P<0.05), and a greater percentage of drinking (44.8% vs 32.6%, P=0.006), but had significantly lowered levels of HbA1c, high-density lipoprotein (HDL), and estimated glomerular filtration rate (eGFR) (P<0.05). SUA was found to be positively correlated with F-CP, 2hP-CP, BMI, waist-to-hip ratio, diastolic blood pressure, TG, HCY, SCr, smoking and drinking (P<0.05), and was negatively correlated with gender, age, age of disease onset, HbA1c, HDL and eGFR (P<0.05). SUA level and the incidence of hyperuricemia increasea significantly with F-CP level (P<0.05). F-CP was identified as an independent risk factor for elevated SUA, and gender did not affect the relationship between F-CP and SUA. ROC curve analysis showed that a F-CP level >1.260 ng/mL was associated with a significantly increased risk of hyperuricemia in T2DM patients.</p><p><b>CONCLUSION</b>F-CP is closely related with SUA and may be an independent risk factor of elevated SUA in patients with T2DM.</p>

Evaluation of retinal nerve fiber layer thickness in patients with obstructive sleep apnea-hypopnea syndrome / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the retinal nerve fiber layer (RNFL) thickness in patients with different severities of obstructive sleep apnea-hypopnea syndrome (OSAHS) versus normal controls.METHODS:This was an observational case-control study.Totally 79 patients presenting with snoring and daytime sleepiness who underwent overnight polysomnography (PSG) to determine OSAHS severity were recruited,and subsequently referred for ophthalmologic evaluation.The data including intraocular pressure (lOP),RNFL thickness etc was collected.RESULTS:A total of 73 subjects were recruited,including 53 patients with OSAHS and 20 normal control subjects.lOP was significantly higher for the moderate and severe OSAHS group than for the control group (both P＜0.05).The RNFL in the average and superior quadrants were significantly thinner for the moderate and severe OSAHS group than for the control group (both P＜0.05).AHI was negatively correlated with RNFL thickness in the superior quadrants,and with average RNFL thickness (r=-0.316,-0.205;both P＜0.01).Negative correlations were also identified between RNFL thickness in the superior quadrants and the ODI (r=-0.24,P =0.005).Positive correlations were identified between SaO2 on PSG and RNFL thickness in the superior quadrants (r=0.277,P=0.001).CONCLUSION:RNFL of the patients with OSAHS is thinned.Furthermore,it is observed that the greater severity of OSAHS,the greater the loss of RNFL.Among the four quadrants observed,the most affected quadrant was the superior quadrant.

Recent advances and perspective in the study of the nano-reinforcing materials for molecular imprinting of proteins / 药学学报

Molecular imprinting technique (MIT) involves the synthesis of polymer in the presence of a template to produce complementary binding sites in terms of its size, shape and functional group orientation. Such kind of polymer possesses specific recognition ability towards its template molecule. Despite the rapid development of MIT over the years, the majority of the template molecules that have been studied are small molecules, while molecular imprinting of proteins remains a significant yet challenging task due to their large size, structural flexibility and complex conformation. This review, we summarized the research findings over the past years, and discussed the nano-reinforcing materials used to prepare molecular imprinting of proteins and the perspective of these nano-reinforcing materials.

Application of recording SK2 current in human atrial myocytes by perforated patch clamp techniques with the mix of beta-escin and amphotericin B / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To establish a perforated patch-clamp technology with amphotericin B and beta-escin and to research the regulation of small conductance calcium-activated potassium channel SK2 currents by calcium ions.</p><p><b>METHODS</b>Single human atrial myocytes were enzymatically isolated from the right atrial appendage. Amphotericin B and / or beta-escin were used by perforated electrode liquid. The regulation of SK2 current by calcium ions in human atrial myocytes was performed with the perforated patch-clamp technique. The intracellular calcium changes were measured by the intracellular calcium test system.</p><p><b>RESULTS</b>Mixed perforated electrode liquid compared with 150 microg/ml amphotericin B or 6.88 microg/ml beta-escin alone, it was easy to seal cells and activate SK2 current by the former method. Moreover, the ration of F340/380 was consistent with the change of intracellular free calcium ion concentration increase after the formation of perforation. The ration of F340/380 was measured by intracellular calcium test system.</p><p><b>CONCLUSION</b>The appropriate concentration of amphotericin B mixed with beta-escin can form a stable whole-cell patch recording technology that is appropriate for the research of SK2 current regulation by intracellular calcium.</p>

Effects of stimulating in the cavum concha on glucometabolism in patients with diabetes / 中国针灸

<p><b>OBJECTIVE</b>To explore the intervention effect of the auricular stimulator in the cavum concha for diabetes.</p><p><b>METHODS</b>Forty-five cases were treated with auricular simulator in the cavum concha for 30 min, once daily for consecutive 3 months. The changes of the fasting plasma glucose (FBG), blood glucose load after 2-hour 75 g oral glucose tolerance test (P2 BG)and glycosylated hemoglobin (HbA1c) were compared before and after treatment.</p><p><b>RESULTS</b>The level of the HbA1c was obviously decreased (P < 0.05, P < 0.01), and there were also statistically significant differences in FBG and P2 BG after the treatment (P < 0.05, P < 0.01).</p><p><b>CONCLUSION</b>With the auricular stimulator, the stimulation in the cavum concha is benefit for the improvement of HbA1c of the diabetes.</p>

Increased small conductance calcium-activated potassium channel (SK2 channel) current in atrial myocytes of patients with persistent atrial fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To compare the amplitude of the SK2 current (small conductance calcium-activated potassium channel) in human atrial myocytes with or without persistent atrial fibrillation (AF).</p><p><b>METHODS</b>Right atrial appendage was obtained from 15 patients with sinus rate (SR) and 7 patients with AF underwent surgical valve replacement. Single myocyte was isolated by enzymatic dissociation method and the SK2 channel current density was recorded using whole-cell patch clamp techniques to detect the changes. Immunofluorescence was used to observe SK2 channel protein distribution on right atrial appendage.</p><p><b>RESULTS</b>Using the whole cell patch-clamp recording techniques, an inward rectifier K(+) mix currents could be obtained from both SR (n = 15) and AF (n = 7) samples, I(K1) mix currents density in single myocyte of AF group was significantly increased than in SR group [(-16.42 ± 5.32) pA/pF vs (-6.59 ± 2.24) pA/pF, P < 0.01], which could be partially inhibited by apamin (100 nmol/L). The apamin-sensitive current was obtained by subtraction of the currents before and after treatment with apamin. SK2 current density was significantly increased in AF group than that of SR group [(-9.81 ± 2.54) pA/pF vs (-3.67 ± 0.37) pA/pF, P < 0.01]. SK2 channel protein was evidenced with immunofluorescence method in right atrial appendage from AF group and SR group.</p><p><b>CONCLUSION</b>SK2 channel protein and current were present in atrial myocytes. The SK2 current density was significantly increased in AF group than in SR group suggesting that the increase of SK2 current might contribute to the electrical remodeling in AF patients.</p>

UTP regulates spontaneous transient outward currents in porcine coronary artery smooth muscle cells through PLC-IP(3) signaling pathway / 生理学报

The aim of the present study was to investigate the effects of inositol 1,4,5-trisphosphate (IP(3))-generating agonist UTP on spontaneous transient outward currents (STOCs), and explore the role of intracellular Ca(2+) release in the current response mediated by IP(3) in porcine coronary artery smooth muscle cells (CASMCs). The coronary artery was excised from the fresh porcine heart and cut into small segments (2 mm × 5 mm) and then transferred to enzymatic dissociation solution for incubation. Single CASMCs were obtained by two-step enzyme digestion at 37 °C. STOCs were recorded and characterized using the perforated whole-cell patch-clamp configuration in freshly isolated porcine CASMCs. The currents were amplified and filtered by patch-clamp amplifier (Axopatch 200B), and then the digitized data were recorded by pClamp 9.0 software and further analyzed by MiniAnalysis 6.0 program. The results were as follows: (1) UTP led to conspicuous increases in STOC amplitude by (57.54±5.34)% and in frequency by (77.46±8.42)% (P<0.01, n=38). (2) The specific blocker of phospholipase C (PLC) - U73122 (5 μmol/L) remarkably reduced STOC amplitude by (31.04±7.46)% and frequency by (41.65±16.59)%, respectively (P<0.05, n=10). In the presence of U73122, UTP failed to reactivate STOCs (n=7). (3) Verapamil (20 μmol/L) and CdCl2 (200 μmol/L), two blockers of L-type voltage-dependent Ca(2+) channels, had little effects on STOCs initiated by UTP (n=8). (4) 1 μmol/L bisindolylmaleimide I (BisI), a potent blocker of protein kinase C (PKC), significantly increased STOC amplitude by (65.44±24.66)% and frequency by (61.35±21.47)% (P<0.01, n=12); UTP (40 μmol/L), applied in the presence of 1 μmol/L BisI, could further increase STOC activity (P<0.05, P<0.01, n=12). Subsequent application of ryanodine (50 μmol/L) abolished STOC activity. (5) In the presence of UTP (40 μmol/L), inhibition of IP(3) receptors (IP(3)Rs) by 2-aminoethoxydiphenyl borate (2-APB, 40 μmol/L) reduced STOC amplitude by (24.08±3.97)% (P<0.05, n=8), but had little effect on STOC frequency (n=8). While application of 2-APB (80 μmol/L) significantly reduced STOC amplitude by (31.43±6.34)% and frequency by (40.59±19.01)%, respectively (P<0.05, P<0.01, n=6). Subsequent application of ryanodine (50 μmol/L) completely blocked STOC activity. Pretreatment of cells with 2-APB (40 μmol/L) or ryanodine (50 μmol/L), UTP (40 μmol/L) failed to reactivate STOCs. The results suggest that UTP activates STOCs mainly via PLC and IP(3)-dependent mechanisms. Complex Ca(2+)-mobilization pathways are involved in UTP-mediated STOC activation in porcine CASMCs.

An improved method for isolation of single atrial myocyte from human heart / 生理学报

To approach the method of isolation of tolerant human atrial myocytes, single myocytes were isolated by modified procedure of enzymatic dissociation with protease (type XXIV) and collagenase (type V). L-type calcium channel current (I(Ca-L)), sodium current (I(Na)), transient outward potassium current (I(to1)), and inward rectifier potassium current (I(K1)) in isolated atrial myocytes were recorded by using whole-cell patch-clamp techniques. Single cardiocytes isolated by this method were smooth, well-striated and rod-shaped. The yields of recordable myocytes, which viable and calcium-tolerant for electrophysiological studies, were 50%-60% of the total isolated cells. Compared with other isolation methods, this method was simple and steady, but with yield of a great number of qualified myocytes. The currents recorded in these cells were functional and active. Our research suggests that the myocytes isolated by the described method in this paper have normal electrophysiological function and are appropriate for patch-clamp experiments.

Characteristic of spontaneous transient outward potassium currents in vascular smooth muscle cells of porcine coronary artery / 生理学报

Spontaneous transient outward currents (STOCs) play an important role in the myogenic regulation of small artery tone, such as coronary artery. In the present study, we investigated the electrophysiological properties and the regulation of STOCs in vascular smooth muscle cells (VSMCs) of porcine coronary artery by perforated patch-clamp technique. Our data showed that STOCs were dependent on voltage and extracellular calcium and they were highly variable in amplitudes and frequencies. STOCs superimposed stochastically onto whole-cell K(+) currents induced by step and ramp protocols. STOCs were completely abolished by ChTX [inhibitor of large-conductance Ca(2+)-activated potassium (BK(Ca)) channels], removal of extracellular Ca(2+), or addition of ryanodine (50 mumol/L) respectively. In contrast, CdCl2 and verapamil, inhibitors of voltage-dependent L-type Ca(2+) channels, had little effect on STOCs. Caffeine (5 mmol/L) transiently increased STOCs (hump), followed by a temporary inhibition. Ca(2+) ionophore A23187 increased both amplitude and frequency of STOCs. Na(+) ionophore monensin increased the frequency of STOCs. STOCs were strongly inhibited by KB-R7943, a selective inhibitor of the reverse mode of the Na(+)/Ca(2+) exchanger. Based on these observations, we conclude that STOCs are mediated by BK(Ca) channels. The generation and activation of STOCs depend upon Ca(2+) influx through Na(+)/Ca(2+) exchange and release of Ca(2+) from sarcoplasmic reticulum (SR) via ryanodine receptors. This suggests that Na(+)/Ca(2+) exchange determines calcium store refilling. Recycling of entering Ca(2+) from superficial SR may locally elevate Ca(2+) concentration at the plasma membrane, thereby activating BK(Ca) channels and then initiating STOCs.

Research of L-type Ca2+ channel current in atrial myocytes of patients with chronic atrial fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the changes of L-type Ca(2+) channel current (I(Ca-L)) and its voltage-dependent activation and inactivation in atrial myocytes of patients with atrial fibrillation (AF).</p><p><b>METHODS</b>The specimens of right atrial appendage were obtained from 18 patients with normal sinus rhythm (NSR) and 12 patients with chronic atrial fibrillation (CAF). Single myocytes were isolated by enzymatic dissociation with two-step method and the ionic currents were recorded using whole-cell patch clamp techniques to detect the changes of I(Ca-L) density and kinetic properties.</p><p><b>RESULTS</b>(1) I(Ca-L) density was (-1.32 +/- 0.19) pA/pF in CAF group (n = 12) and (-4.58 +/- 0.39) pA/pF in NSR group (n = 21) at the test potential from -40 mV to 0 mV. I(Ca-L) density of CAF group was significantly reduced (P < 0.01), compared with the NSR group. (2) No significant differences were noted between the two groups in the voltage-dependent activation parameters (V(1/2), K) and inactivation parameters (V(1/2), K).</p><p><b>CONCLUSIONS</b>I(Ca-L) density of CAF group was significantly decreased whereas it's voltage-dependent kinetic properties had no change. This phenomenon may be one of the mechanisms of atrial electrophysiological remodeling in chronic atrial fibrillation.</p>

Human inward rectifying potassium current and Kir2.1 mRNA expression in myocytes isolated from patients with chronic atrial fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To compare the changes of both inward rectifying K(+) (Kir) current(I(k1)) density and mRNA expression level of Kir2.1, a major subfamily of Kir in chronic human atrial fibrillation (CAF) with those in normal sinus rhythm (NSR).</p><p><b>METHODS</b>I(k1) density was measured with whole-cell patch clamp technique in single myocyte isolated by an enzymatic dissociation method from right atrial appendages in patients with CAF (n = 8) and those with NSR (n = 12). The mRNA expression levels of Kir2.1 was determined in right atrial appendages from CAF (n = 19) and NSR (n = 18) by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR).</p><p><b>RESULT</b>The average resting membrane potentials were similar between CAF and NSR (-78.95 mV +/- 4.67 mV and -70.22 mV +/- 11.08 mV, P>0.05). I(k1) density in single myocyte significantly increased at hyperpolarized potential level (-100 mV) in CAF compared to that in NSR (-9.59 pA/pF +/- 2.47 pA/pF vs. -5.58 pA/pF +/- 2.52 pA/pF, P<0.01). The mRNA level of Kir2.1 was also significantly higher in CAF than that of NSR (0.50+/-0.16 vs. 0.34+/-0.09, P<0.05).</p><p><b>CONCLUSION</b>The data suggest that Kir2.1 up-regulation and I(k1) current increase might contribute to the electrical remodeling in CAF patients.</p>

Effects of tetramethylpyrazine on large-conductance Ca²⁺-activated potassium channels in porcine coronary artery smooth muscle cells / 生理学报

The aim of the present study was to examine the effects of tetramethylpyrazine (TMP) on large-conductance Ca(2+)-activated potassium channels (BK(Ca) channels) in porcine coronary artery smooth muscle cells, in order to provide the experimental evidence for expounding the mechanism of TMP in dilating coronary artery. Cell-attached and inside-out single channel recording techniques were used to observe the effects of TMP on BK(Ca) channels as well as the effects after the cells were treated by protein kinase A (PKA) inhibitor or protein kinase G (PKG) inhibitor. In inside-out patch, TMP activated BK(Ca) channels by increasing open-state probability (N(Po)) and decreasing close time (Tc) in a concentration-dependent manner. TMP (0.73~8.07 mmol/L) in the bath solution increased N(Po) from (0.01+/-0.003) to (0.03+/-0.01)~(1.21+/-0.18) (P<0.01, n=10), and decreased Tc from (732.33+/-90.67) ms to (359.67+/-41.30) ~ (2.96+/-0.52) ms (P<0.01, n=10). These actions of TMP occurred even when the free Ca(2+) concentration in the bath was reduced to ~ 0 mmol/L. The specific inhibitors of PKA (H-89, 3 mumol/L) and PKG (KT-5823, 1 mumol/L) had no influence on the activation of TMP on BK(Ca) channels. These findings suggest that TMP can directly activate BK(Ca) channels in coronary artery smooth muscle, which probably is an important mechanism in dilating coronary artery.

Effect of IP3 on BK channels of porcine coronary artery smooth muscle cells / 生理学报

D-myo-inositol 1,4,5-trisphosphate (IP(3)) plays an important role in signal transduction. It releases Ca(2+) from intracellular sites, which activates the Ca(2+)-dependent channels such as large-conductance Ca(2+)-activated potassium channels (BK channels). The present study was therefore designed to determine if the activity of BK channels in porcine coronary artery smooth muscle cells was increased by IP(3). Using the inside-out patch-clamp technique, the activity of single BK channels was recorded in porcine coronary artery smooth muscle cells. In excised inside-out membrane patches, IP(3) (10-50 micromol/L) enhanced the open probability (Po) of BK channels in a dose-dependent manner in the intracellular side of inside-out patches and its effect was almost completely abolished by washout. The open-state probability of the BK channels increased from a control level of 0.0402+/-0.0152 to 0.1365+/-0.0212 (20 micromol/L IP(3)) and 0.1865+/-0.0175 (30 micromol/L IP(3)). IP(3) decreased the mean close time markedly, but had no effect on the amplitude of BK channels. The activation of IP(3) on BK channels did not decline. The metabolite of IP(3) had no obvious effect on BK channels. This study provides evidence that IP(3) activates BK channels in porcine coronary artery smooth muscle cells in a dose-dependence manner.