[Role of TRPC6 in pulmonary artery smooth muscle cells proliferation and apoptosis under hypoxia and hypercapnia].

The present study was to investigate the role of TRPC6 in pulmonary artery smooth muscle cells (PASMCs) proliferation and apoptosis under hypoxia and hypercapnia. PASMCs were isolated from chloral hydrate-anesthetized male Sprague-Dawley (SD) rats. Cellular purity was assessed by immunofluorescence staining for smooth muscle α-actin under fluorescence microscopy. Passage 4-6 PASMCs were starved for 24 h in serum-free DMEM and divided into 5 groups randomly: normoxia, hypoxia and hypercapnia, DMSO, TRPC6 inhibitor SKF-96365 and TRPC6 activator OAG groups. The normoxic group was incubated under normoxia (5% CO2, 21% O2, 37 °C) for 24 h, and the others were incubated with corresponding drugs under hypoxic and hypercapnic (6% CO2, 5% O2, 37 °C) atmosphere for 24 h. TRPC6 mRNA was detected by reverse transcription-PCR. TRPC6 protein was detected by Western blotting. The proliferation of PASMCs was performed by CCK-8 kit. Apoptosis of the PASMCs was detected using TUNEL assay. The [Ca2+]i in the PASMCs was measured using Fura 2-AM fluorescence. The results showed that the expressions of TRPC6 mRNA and protein, and [Ca2+]i were upregulated under hypoxic and hypercapnic conditions. Hypoxia and hypercapnia promoted cellular proliferation and inhibited apoptosis in the PASMCs. OAG enhanced the above-mentioned effects of hypoxia and hypercapnia, whereas SKF-96365 reversed these effects. These results suggest that TRPC6 may play a role in PASMCs proliferation and apoptosis under hypoxia and hypercapnia by regulating [Ca2+]i.

[The effects of ERK1/2 pathway on the expression of calcium activated chloride channel in hypoxia in PASMCs rat model].

OBJECTIVE: To investigate the expression of mRNA and protein of Calcium activated chloride channel (CLCA2) in hypoxic pulmonary artery smooth muscle cell (PASMCs) of rat and it's relationship with ERK1/2 signal pathway. METHODS: PASMCs were randomly divided into 5 groups including normal group(N group), hypoxia group(H group), DMSO group(D group), U0126 group (U group) and Staurosporine aglycone group(SA group). The protein expression of CLCA2 in PASMCs was detected by Western blot.The mRNA expression of CLCA2 was detected by half quantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: The mRNA and protein expressions of CLCA2 in H group were significantly higher than N group (P<0.01). Comparing with D group,the mRNA and protein expressions of CLCA2 were significantly increased in U group (P<0.01),the mRNA expression of CLCA2 in SA group was obviously decreased (P<0.01) with slightly decreasing of its protein expression. CONCLUSIONS: Hypoxia promotes the expressions of mRNA and protein of CLCA2 in rat PASMCs. The ERK1/2 pathway activator Staurosporine aglycone reduces the mRNA and protein expression of CLCA2 in rats PASMCs and the ERK1/2 pathway inhibitor U0126 induces the upregulation of the mRNA and protein expressiosn of CLCA2 in rats PASMCs.

[The regulation of MAPK signaling pathway on cell proliferation and apoptosis in hypoxic PASMCs of rats].

OBJECTIVE: To explore the relationship between hypoxic pulmonary arterial smooth muscle cells(PASMCs)proliferation, apop-tosis and mitogen-activated protein kinases(MAPK) signal pathway in rats. METHODS: PASMCs were obtained from male SD rats by the enzyme digestion method and primarily cultured; PASMCs were identified through two methods:immunofluorescence staining and light microscopy; the 4~6th generation PASMCs of logarithmic growth state of good growth period were selected, and randomly divided into 7 groups:normoxic con-trol group (N), hypoxia group (H), DMSO group (D), extracellular signal-regulated kinase1/2(ERK1/2) inhibitor-U0126 group (U) and p38MAPK inhibitor-SB203580 group (S), the p38MAPK activator-Anisomycin group (A), the ERK1/2 activator-Staurosporine Aglycone group (SA). When all the models were completed, the all groups joined the CCK-8 to measure cell proliferation; cell apoptosis of each group was detected by TUNEL kit after the modeling. RESULTS: Compared with N group, the expression of OD value in H group was up-regulated (0.990 ±0.041 vs 1.143 ±0.033,P < 0.01). There was no statistical significance on PASMCs apoptosis index(AI) in H group (4.913 ±0.451 vs 5.452 ±0.557, P > 0.05); Compared With H group, there were no statistical significance on the expression of PASMCs OD value and apoptosis index(AI)in D group (1.143 ±0.033 vs 1.142 ±0.049,5.452 ±0.557 vs 5.402 ±0.651,P > 0.05); the expression of OD value in U group was down-regulated, and the expression of AI was up-regulated (1.143 ±0.033 vs 0.985 ±0.078, 5.452 ±0.557 vs 10.145 ±2.545, P < 0.01); the expression of OD value in S group was up-regulated, and the expression of AI was down-regulated (1.143 ±0.033 vs 1.295 ±0.039, 5.452 ±0.557 vs 3.093 ±0.409, P < 0.01); the expression of OD value in A group was down-regulated, and the expres-sion of AI was up-regulated (1.143 ±0.033 vs 0.347 ±0.067, 5.452 ±0.557 vs 25.753 ±1.262, P < 0.01); the expression of OD value in SA group was up-regulated, and the expression of AI was down-regulated (1.143 ±0.033 vs 1.685 ±0.100, 5.452 ±0.557 vs 1.700 ±0.095, P < 0.01). CONCLUSIONS: The regulation of PASMCs' proliferation and apoptosis under hypoxia condition have a relationship with the participation of MAPK signal pathway.

[The effects and mechanisms of ligustrazine injection on pulmonary arterial hypertension in COPD patients].

OBJECTIVE: To observe the effects of ligustrazine hydrochloride injection(LHI) on pulmonary arterial hypertension in chronic obstructive pulmonary disease(COPD) patients and to investigate its possible mechanisms. METHODS: Twenty-two cases of patients with COPD were randomly divided into conventional treatmentgroup (group C) and ligustrazine treatment group(group L), 11 persons were randomly selected from healthy subjects without lung disease served as normal control group(group N). Group C was given bed rest, low flow oxygen inhalation, bronchial diastolic agent, glucocorticoid and antibiotics and other conventional treatment, and group L was added with ligustrazine hydrochloride injection on the above mentioned basis treatment, group N was given no treatment. After 2 weeks, lung function, blood gas analysis and pulmonary arterial pressure were compared among the three groups, and the content of H2S in plasma was tested with sensitive sulfur electrode method. RESULTS: ①After two weeks treatment, in group L and group C pulmonary function, blood gas analysis, pulmonary artery pressure were obviously improved, and group L was better than group C (P<0.05); ② In group L the content of H2S was increased (P<0.01), group C had no significant difference (P>0.05), and there was a significant difference between the two groups (P<0.01). CONCLUSIONS: Combination with LHI can effectively improve lung function. LHI mayrelieve hypoxic hypercapnia pulmonary hypertension induced by COPD through raising the content of H2S.

[Effect of ERK1/2 on rat pulmonary artery smooth muscle cells Kv1.5 channel in the process of hypoxia].

OBJECTIVE: To explore the effect of ERK1/2 MAPK pathway on the expression of Kv1.5 channel, a voltage-gated potassium ion channel, in rat pulmonary artery smooth muscle cells (PASMCs) and its mechanisms during the process of hypoxia. METHODS: The PASMCs derived from SD rats were cultivated primarily. The third to sixth generation of PASMCs were divided into 5 groups randomly: (1) Normal group (N); (2) Hypoxic group (H); (3) Demethy sulfoxide(DMSO) group (HD); (4) U0126 group (HU): 10 micromol/L U0126; (5) Anisomycin group (HA): 10 micromol/L anisomycin. There were three dishes of cells in each group. The cells in normal group were cultured in normoxic incubator (5% CO2, 37 degrees C), the cells in other groups were added to 0.05% DMSO in the hypoxic incubator (5% CO2, 2% O2, 37 degrees C), all cells were cultured for 60 h. RT-PCR and Western blot were used to detected the espressions of Kv1.5 mRNA and protein in PASMCs. RESULTS: Compared with N group, the expressions of Kv1.5 mRNA and protein in H, HD and HA groups were reduced significantly (P < 0.05); Compared with H group and HD groups, Kv1.5 mRNA and protein expressions in HU group were increased sharply (P < 0.05). Compared with the HU group, Kv1.5 mRNA and protein expressions in HA groups were significantly lower (P < 0.05). CONCLUSION: Low oxygen reduced Kv1.5 mRNA and protein expressions, U0126 could resistant the Kv1.5 channel lower expression caused by hypoxia. Anisomycin had no significant effect on Kv1.5 channel expression under hypoxia, but the expression of Kv1.5 was still significantly lower than the normal oxygen group. These data suggest that hypoxia may cause hypoxic pulmonary hypertension by interfering ERK1/2 signaling pathway to inhibit Kv1.5

Effect of panax notoginseng saponins injection on the p38MAPK pathway in lung tissue in a rat model of hypoxic pulmonary hypertension.

OBJECTIVE: To investigate the effect of panax notoginseng saponins (PNS) injection on pulmonary artery pressure and the expression of p38MAPK in lung tissue of rats subjected to chronic hypoxia. METHODS: Thirty adult male Sprague Dawley rats were randomly divided into three groups (ten in each group): rats in control group were exposed to normoxic condition and the rats in hypoxia group and PNS group were subjected to 4-week hypoxia, and PNS injection (50 mg · kg(-1) · d(-1)) was administrated intraperitoneally at 30 min in the PNS group daily before the rats were kept in the hypoxic chamber, while rats in the other two groups received equal dose of normal saline instead. After chronic hypoxia, mean pulmonary artery pressure (mPAP) and mean carotid artery pressure (mCAP) were measured. The heart and lung tissues were harvested, and right ventricle (RV) and left ventricle plus ventricular septum (LV+S) were weighed to calculate the ratio of RV/(LV+S). The expression of p38MAPK mRNA was determined by reverse transcription-polymerase chain reaction, the quantity of phosphorylated p38MAPK (p-p38MAPK) in rat lung tissues and pulmonary arterioles was determined by Western blot and immunohistochemistry. RESULTS: Compared with the control group, mPAP and the ratio of RV/(LV+S) in the hypoxia group were increased, the expression of p-p38MAPK in pulmonary arterioles and p38MAPK mRNA in the lung were higher (P<0.05). The changes of these parameters in the hypoxia group were significantly attenuated by PNS treatment (P<0.05). CONCLUSION: PNS injection was shown to prevent hypoxic pulmonary hypertension at least partly by regulating p38MAPK pathway.

[Expression of KATP in pulmonary artery smooth muscle cells under hypoxia-hypercapnia condition and the relationship with p38 MAPK pathway].

The aim of the present study is to investigate the expressions of ATP-sensitive K(+) channels (KATP) in pulmonary artery smooth muscle cells (PASMCs) and the relationship with p38 MAPK signal pathway in rats. Male SD rat PASMCs were cultured in vitro, and a model of hypoxia and hypercapnia was reconstructed. PASMCs were divided to normal (N), hypoxia-hypercapnia (H), hypoxia-hypercapnia+DMSO incubation (HD), hypoxia-hypercapnia+SB203580 (inhibitor of p38 MAPK pathway) incubation (HS) and hypoxia-hypercapnia+Anisomycin (agonist of p38 MAPK pathway) incubation (HA) groups. Western blot was used to detect the protein expression of SUR2B and Kir6.1; semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA expression of SUR2B and Kir6.1. The results demonstrated that: (1) Compared with N, H, HD and HS groups, the expressions of Kir6.1 mRNA and protein in PASMCs of HA group were decreased significantly (P < 0.01), but there were no differences among N, H, HD and HS groups (P > 0.05); (2) Compared with N group, the expressions of SUR2B mRNA and protein in H, HD, HS and HA groups were increased significantly (P < 0.05), but there were no differences among H, HD, HS and HA groups (P > 0.05). The results imply that: (1) Hypoxia-hypercapnia, SB203580 didn't change the expressions of Kir6.1 mRNA and protein in PASMCs, but Anisomycin decreased the expressions of Kir6.1 mRNA and protein, so Kir6.1 may be regulated by the other subfamily of MAPK pathway; (2) Hypoxia-hypercapnia raised SUR2B mRNA and protein expressions in PASMCs, but SB203580 and Anisomycin did not affect the changes, so the increasing of SUR2B mRNA and protein induced by hypoxia-hypercapnia may be not depend on p38 MAPK pathway.