TRPV4 channel mediates the increase of pulmonary microvascular endothelial permeability in rats with chronic hypoxic pulmonary hypertension / 生理学报

The purpose of the present study was to investigate the effect of transient receptor potential vanilloid 4 (TRPV4) channel on the permeability of pulmonary microvascular endothelial cells (PMVECs) in rats with chronic hypoxia-induced pulmonary hypertension (CHPH), so as to clarify the mechanism of vascular endothelial dysfunction during the occurrence of pulmonary hypertension (PH). CHPH rat model was established by exposure to chronic hypoxia (CH) for 21 days. Primary PMVECs were cultured by adherent tissue blocks at the edge of the lung. The permeability coefficient of primary cultured PMVECs was detected by fluorescein isothiocyanate (FITC)-dextran. The structure of tight junction (TJ) was observed by transmission electron microscope. The expression of TRPV4 and TJ-related proteins, such as, Occludin, Claudin-5, ZO-1 were examined by real-time fluorescence quantitative PCR and Western blotting. The intracellular calcium concentration ([Ca

The protective effect of cyclosporine A on daunorubicin injured H9c2 cardiomyoblasts / 中国药理学通报

Aim To study the protective effect of cyclosporine A (CsA) on daunorubicin (DNR) injured H9c2 cardiomyoblasts. Methods H9c2 cells were pre-treated with CsA for 2 hours, then co-cultured with 1 μmol · L

Alteration of tetraethylammonium-sensitive potassium current in pulmonary artery smooth muscle cells of pulmonary hypertension rats / 中国药理学通报

Aim To investigate the alteration of volt-age-depending potassium channel(KV) current in pul-monary arterial smooth muscle cells(PASMCs) of pul-monary hypertension (PH) rats, and the effect of tet-raethylammonium (TEA,a blocker of KV) on potassi-um channel current in different PH models. Methods The whole-cell patch clamp techniques were applied to record the KVcurrents from PASMCs cultured with Ham's F-12 (1% FBS). Furthermore, the effects of TEA on the KVcurrents were examined in different PH models. Results The whole-cell KVcurrents were ob-viously inhibited in PASMCs of chronic hypoxia (CH)and monocrotaline (MCT)-treated rats. TEA signifi-cantly decreased the whole-cell KVcurrents in PASMCs of control and PH rats,and the inhibitory effect of TEA was dramatically reduced in PH group. Conclusions The degree of the voltage-dependent potassium chan-nels opening is significantly inhibited in PASMCs of CH and MCT-treated rats,accordingly,the TEA-sen-sitive KVcurrents obviously decrease.

Comparison of the synchronous changes of vascular tension and intracellular Casignal in third-order branches of mesenteric arteries under the different objective amplification of confocal microscope / 生理学报

This study was aimed to establish an optimized method to observe the synchronous changes of vascular tension and intracellular Casignal in the third-order branches of mesenteric arteries (sMA, diameter: 100-300 μm). The vascular tension and intracellular Casignal changes in response to potassium chloride (KCl), endothelin-1 (ET-1) and Gdwere detected using confocal wire myograph system and confocal laser scanning microscopy imaging technique, respectively. The experimental results were analyzed to explore the optimal experimental conditions. The results showed that KCl caused contraction in sMA significantly, and the intracellular Calevel of vascular smooth muscle cells (VSMCs) was also increased under 20× and 40× objective lens. Compared with those under the 40× objective lens, the Casignal change was larger and the fluorescence value was more stable under the 20× objective lens, whereas the Casignal change was not obvious under the 10× objective lens. ET-1 (1-10 nmol/L) caused concentration dependent contraction in sMA significantly, and the intracellular Casignal of VSMCs was also enhanced in a concentration dependent manner. Additionally, Gdsignificantly reduced the contraction of sMA and the intracellular Casignal of VSMCs caused by ET-1. The results suggest that the intracellular Casignal of VSMCs changes with vascular contraction or relaxation caused by the agonists or antagonists of Cachannels. We successfully recorded both changes synchronously using confocal wire myograph system and confocal laser scanning microscopy imaging technique at the same time. Based on the analysis of the experimental results, we concluded that 20× objective lens provides the best experimental condition. Compared to combination of vascular tone detection method and real-time cellular fluorescence imaging technique, the present synchronous method is convenient and helpful to reduce experimental error.

Comparison of agonists-induced contraction between main and the third-order branches of pulmonary arteries in rats / 生理学报

This study was designed to observe the differences between main pulmonary arteries and the third-order branches of pulmonary arteries in the contractile response to phenylephrine (Phen), endothelin-1 (ET-1) and potassium chloride (KCl). The vascular tension changes of main and the third-order branches of pulmonary arteries induced by KCl, ET-1 and Phen were recorded by traditional vascular tone detection methods and microvascular ring technique, respectively. The results showed that Phen could cause a significant contraction in main pulmonary arteries, but did not induce apparent contraction in the third-order branches of pulmonary arteries. Compared with main pulmonary arteries, ET-1 contracted the third-order branches of pulmonary arteries with reduced maximal response value and PDvalue. In comparison with the main pulmonary arteries, contraction caused by KCl was enhanced in the third-order branches of pulmonary arteries. The results suggest that the vascular reactivity of main and the third-order branches of pulmonary arteries is different and it is important to study the vascular function of small branches of pulmonary arteries. This study could provide an important experimental basis for the further study on vascular function of small branches of pulmonary arteries and the functional changes in pulmonary hypertension.

Effects of chronic hypoxia on left and right ventricular function and the expression of cardiac TRPC channels in rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the effects of chronic hypoxia on left and right ventricular function and the expression of cardiac transient receptor potential canonical (TRPC) channels in rats.</p><p><b>METHODS</b>Forty eight SD male rats were randomly divided into control group (CON) and chronic hypoxic pulmonary hypertension model group (CH) (n = 24). In CH group, rats were exposed in chronic hypoxia environment (10% +/- 0.2% O2) to induce myocardial hypertrophy. After 3 weeks, mean systemic arterial pressure (mSAP), right ventricular systolic pressure (RVSP), left ventricular systolic pressure (LVSP), left or right ventricular pressure maximum rate of rise (LV/RV + dp/dt(max)), left or right ventricular pressure maximum rate of descent (LV/RV-dp/dt(max)), right ventricular hypertrophy index (RVMI) and left ventricular hypertrophy index (LVMI) were measured. Left and right ventricular myocardium tissue sections were stained by HE and observed under light microscope. Real-time polymerase chain reaction (real-time-PCR) and Western blot were performed to detect the expression of TRPC subfamily.</p><p><b>RESULTS</b>RVSP, RVMI, RV + dp/dt(max) and RV-dp/dt(max) were markedly elevated in CH group (P < 0.01) in comparison to CON group. LVMI was markedly reduced in CH group in comparison to CON group (P < 0.01). LVSP, LV + dp/dt(max) and LV- dp/dt(max) had no significant changes in CH group in comparison to CON group. Right ventricular myocardial cells of CH group became thick, the nuclei stained deeply, the shape of nuclei became not regularity. Left ventricular myocardial fibers did not change significantly. There was significant difference in the levels of mRNA and protein of TRPC1 between CON and CH groups.</p><p><b>CONCLUSION</b>For three weeks exposed to chronic hypoxia induced right ventricular hypertrophy specifically, raised the mRNA and protein expression of TRPC1 on right ventricular myocardial cells . TRPC1 might be involved in the development of cardiac hypertrophy.</p>

Decreased amplitude of Ca²⁺i elevation induced by menthol in pulmonary arterial smooth muscle cells of pulmonary hypertensive rats / 生理学报

The study was designed to explore the alteration of intracellular calcium concentration ([Ca²⁺]i), induced by transient receptor potential melastatin 8 (TRPM8) channel-specific agonist menthol, in pulmonary arterial smooth muscle cells (PASMCs) between control and pulmonary hypertensive (PH) rats. PH rat models were established by means of chronic hypoxia (CH) and monocrotaline (MCT) injection, respectively. PASMCs from control and PH rats were cultured. The change of [Ca²⁺]i in PASMCs induced by menthol, and the effect of TRPM8 channel-specific antagonist BCTC on the change of [Ca²⁺]i, were observed. Cellular localization of TRPM8 was examined by using immunohistochemistry. Results showed that menthol increased [Ca²⁺]i in the control PASMCs both in Ca²⁺ -normal and Ca²⁺ - free Tyrode's solutions, and at the same time BCTC could inhibit these two kinds of elevations. Compared with the control group, elevations of [Ca²⁺]i were decreased notably in CH- and MCT-pretreated PASMCs superfused with 2 mmol/L Ca²⁺ - or 0 Ca²⁺ -Tyrode's solutions. Immunohistochemical localization experiments showed that the whole PASMCs were dyed brown except for the nucleus. This study verified that TRPM8 exists both in membrane and sarcoplasmic reticulum of PASMCs. In addition, CH- and MCT-pretreatment could independently down-regulate the Ca²⁺ influx and Ca²⁺ release mediated by TRPM8 channel.

TRPC6 mediates the enhancements of pulmonary arterial tone and intracellular Ca2+ concentration of pulmonary arterial smooth muscle cells in pulmonary hypertension rats / 生理学报

Pulmonary arterial hypertension is associated with profound vascular remodeling and alterations in Ca2+ homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Recent studies show that canonical transient receptor potential channel 6 (TRPC6) genes, which encode receptor-operated cation channels (ROCC) in PASMCs, play an important role in Ca2+ regulation and cell proliferation. The aim of the present study was to investigate the role of TRPC6 in monocrotaline (MCT)-induced pulmonary artery hypertension. Sprague-Dawley rats were randomly divided into normal control group and MCT group. In MCT group, pulmonary arterial hypertension was induced by a single intraperitoneal injection of MCT at a dose of 60 mg/kg. After 3 weeks, the right ventricular systolic pressure (RVSP) and the right ventricular mass index (RVMI) were measured. The lung sections were stained by HE and observed under light microscope. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot were performed to detect the expression of TRPC6 in rat pulmonary arteries. The 1-oleoyl-2-acetyl-sn-glycerol (OAG)-induced contractile tension of pulmonary arteries were measured by vascular ring tension analysis and the intracellular Ca2+ concentration ([Ca2+](i))of PASMCs was monitored using Fluo3-AM assay. The results showed that RVSP and RVMI markedly elevated in MCT group (P<0.01) in comparison to CON group. The thickness of pulmonary vascular smooth muscles was increased and the inner diameter of pulmonary arteries was diminished in MCT group. Though there was no significant difference in the levels of mRNA and protein of TRPC6 between CON and MCT groups, the application of OAG, which can directly activate ROCC, induced greater contraction tension of pulmonary arteries (P<0.01) and more Ca2+ entries in PASMCs (P<0.05) in MCT group compared to those in control group. These results indicate that MCT induces pulmonary artery hypertension and thus remodeling of the right ventricle and pulmonary arteries in rats. The expression of mRNA and protein of TRPC6 is not potentiated by MCT, but the TRPC6/ROCC-mediated Ca2+ entry in PASMCs and vascular tone of pulmonary arteries are significantly increased with MCT treatment.