Pulmonary hypertension (PAH) is a common clinical syndrome characterized by elevated pulmonary arterial pressure. The pathological changes in PAH include increased vasoconstrictor tone, thrombosis in situ and pulmonary vascular remodeling. Pulmonary arterial smooth muscle cell (PASMC) proliferation is a hallmark of pulmonary vascular remodeling, and exploration of the molecular mechanisms of PASMC proliferation and intervention of the involved signaling pathways is therefore of great importance for prevention and treatment of PAH. This review focus primarily on the current understanding of the molecular mechanisms involved in the proliferation of PASMCs.
Cell Proliferation ; Humans ; Hypertension, Pulmonary ; Lung ; Myocytes, Smooth Muscle ; cytology ; Pulmonary Artery ; cytology ; Signal Transduction ; Vascular Remodeling

OBJECTIVETo evaluate the roles of Na+/H+ exchanger-1 (NHE-1) in the proliferation and apoptosis of pulmonary artery smooth muscle cells in rats.

METHODSTwenty Wistar rats were randomized into control group and 3-week hypoxic group. Intracellular pH (pHi) of the smooth muscle was determined with fluorescence measurement of the pH-sensitive dye BCECF-AM, and the expression of NHE-1 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). Primary culture of pulmonary artery smooth muscle cells in vitro was performed. In situ cell death detection kit (TUNEL) was used for studying the effect of specific NHE-1 inhibitor-dimethyl amiloride (DMA) on the apoptosis of muscle cells which had intracellular acidification.

RESULTSpHi value and NHE-1 mRNA expression of pulmonary artery smooth muscle cells were significantly higher in the hypoxic group than in the control group (P < 0.01, P < 0.001). DMA elevated the apoptotic ratio remarkably. The effect was enhanced when DMA concentration increased and the time prolonged.

CONCLUSIONSWith the function of adjusting pHi, NHE-1 may play an important role in the proliferation and apoptosis of pulmonary artery smooth muscle cells.

Animals ; Apoptosis ; Cell Division ; Male ; Muscle, Smooth, Vascular ; cytology ; Pulmonary Artery ; cytology ; Rats ; Rats, Wistar ; Sodium-Hydrogen Exchangers ; physiology

Angiotensin II ; pharmacology ; Cells, Cultured ; Focal Adhesion Protein-Tyrosine Kinases ; metabolism ; Humans ; Myocytes, Smooth Muscle ; cytology ; Pulmonary Artery ; cytology

The effects of 3, 4-Dihydroxyacetophenone (3, 4-DHAP) on cytosolic free calcium [Ca2+]i in pulmonary artery endothelia (PAECs) and smooth muscle cells (PASMCs) during acute hypoxia were studied. Porcine pulmonary artery endothelial and smooth muscle cells (PASMCs) were cultured primarily, and they were divided into 4 groups: groups incubated under normoxia or hypoxia and those with or without treatment with 3,4-DHAP. The [Ca2+]i of both PAECs and PASMCs was measured by determining the fluorescence of fura 2 AM on spetrofluorometer. Our results showed that hypoxia caused significant elevation of [Ca2+]i, in both PAECs and PASMCs, 3,4-DHAP could attenuate the hypoxic elevation of [Ca2+]i only in PASMCs but not in PAECs. It is concluded that 3,4-DHAP decreases the hypoxic elevation of [Ca2+]i in PASMCs. This might contribute to its inhibitory effect on hypoxic pulmonary vasoconstriction.
Acetophenones/*pharmacology ; Calcium/*metabolism ; Cell Hypoxia ; Cells, Cultured ; Endothelium, Vascular/cytology ; Endothelium, Vascular/*metabolism ; Muscle, Smooth, Vascular/cytology ; Muscle, Smooth, Vascular/*metabolism ; Pulmonary Artery/cytology ; Pulmonary Artery/metabolism ; Swine

OBJECTIVETo investigate the effect of telomerase reverse transcriptase (TERT) to the proliferation of 5-HT induced pulmonary artery smooth muscle cells (PASMCs).

METHODSThe PASMCs proliferation experiment was performed to detect the effort on PASMCs of 5-HT or ASODN TERT (antisense oligoribonucleotides TERT designed according to the rat TERT mRNA sequence of gene bank). The immunohistochemistry staining experiment and the in situ hybridization experiment were to detect the TERT protein and mRNA expression with 5-HT or ASODN TERT. FITC marked ASODN TERT experiment was done to research the distribution of ASODN TERT in PASMCs.

RESULTS5-HT promoted PASMCs proliferation in a dose-dependent manner (10(-9) - 10(-5) mol/L). 5-HT also significantly increased TERT expression at protein and mRNA levels as shown by immunohistochemistry staining and the in situ hybridization studies. This effect could be blocked by ASODN TERT in a time and dose-dependent manner.

CONCLUSIONSOur experiments show TERT is one of the key factors in the procession of 5-HT induced PASMCs proliferation. ASODN TERT might be a potential therapy agent for pulmonary hypertension.

Animals ; Cell Proliferation ; Cells, Cultured ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; Pulmonary Artery ; cytology ; RNA Replicase ; RNA, Messenger ; genetics ; Rats ; Serotonin ; pharmacology ; Telomerase ; pharmacology

AIMTo investigate the impact of human urotensin II (hUII) on pulmonary arterial smooth muscle cell (PASMCs) cycle in vitro.

METHODSPASMCs dissected from Wistar rats were cultured in vitro, and incubated with series of concentrations of hUII (10(-7) mol/L, 10(-8) mol/L, 10(-9) mol/L) for 12 hours under normoxia or hypoxia condition, in order to analyze cell cycle progression and sub-G1 of PASMCs by using flow cytometric analysis stain of propidium iodide, which represented the proliferative and apoptotic changes in PASMCs.

RESULTSThe study showed a dose-dependent effect of hUII on PASMCs proliferation, which reflected the increase both in percentage of S phase of cell cycle and proliferative index (PI). The response of PASMCs to hUII was different under normoxic and hypoxic conditions. Compared with the control group, the treatment of 10(-7) mol/L, 10(-8) mol/L and 10(-9) mol/L hUII produced an increase of 175%, 136% and 118% under normoxia, respectively, and 135%, 118% and 103% under hypoxia, respectively. The concentration 10(-7) mol/L hUII played a significant role in PASMCs proliferation both under hypoxia and normoxia (P < 0.01). The results of cell cycle did not show sub-G1 of PASMCs at various concentrations of hUII.

CONCLUSIONhUII may stimulate DNA synthesis in S phase cell cycle of PASMCs and the proliferation of PASMCs under normoxia and hypoxia conditions, which promote cell growth in a dose-dependent manner.

Animals ; Cell Cycle ; drug effects ; Cells, Cultured ; Humans ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; drug effects ; Pulmonary Artery ; cytology ; Rats ; Rats, Wistar ; Urotensins ; pharmacology

AIMTo investigate the effect of fractalkine on cell proliferation of cultured rat pulmonary artery smooth muscle cells (PASMCs) in vitro.

METHODSRat PASMCs were cultured in vitro, and treated with different concentrations (10(-10), 10(-9), 10(-8) mol/L) of fractalkine for 12 h, 24 h and 48 h. The cell proliferation was quantified by MTT assay. The cell cycle of PASMCs was measured by flow cytometric(FCM) analysis.

RESULTSMTT assay showed that fractalkine promoted significantly the proliferation of PASMCs, and the effect was concentration-dependent. FCM analysis indicated that fractalkine increased the percentage of S phase and proliferative index (PI). The percentage of S phase and PI of PASMCs were increased after treated with fractalkine for 12 hours, which reached a maximal level at 24 hours.

CONCLUSIONFractalkine promotes rat PASMCs proliferation in a concentration-dependent manner.

Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Chemokine CX3CL1 ; pharmacology ; Male ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; drug effects ; Pulmonary Artery ; cytology ; Rats ; Rats, Sprague-Dawley

AIMTo investigate changes of VEC and CEC under acute hypoxia.

METHODSObserve CEC in blood under acute hypoxia morphologically and count the number of CEC by optical microscope, measure LDH activity of young CEC and VEC by histochemical staining image analysis.

RESULTSLDH activities of VEC in hypoxic groups are lower than that in the group before hypoxia and decrease progressively with hypoxia time. LDH activities of young CEC in groups after hypoxia and before hypoxia are the same and are apparently lower than that of VEC. Before hypoxia most of CEC are aging, the number of CEC from hypoxic groups is greater than that before hypoxia and increases progressively with hypoxia time and most of CEC from hypoxic groups are young.

CONCLUSIONThe morphology and number of CEC may reflect the extent to which the vascular is injured. LDH activity of VEC may reflect the transformation from VEC into CEC. LDH activity of young CEC may reflect the extent to which the VEC is injured when falling from vascular wall.

Animals ; Blood Cell Count ; Blood Circulation ; Endothelial Cells ; cytology ; Endothelium, Vascular ; cytology ; Hypoxia ; Lactate Dehydrogenases ; metabolism ; Pulmonary Artery ; cytology ; Rats ; Rats, Wistar

The effects of 3, 4-Dihydroxyacetophenone (3, 4-DHAP) on cytosolic free calcium [Ca2+]i in pulmonary artery endothelia (PAECs) and smooth muscle cells (PASMCs) during acute hypoxia were studied. Porcine pulmonary artery endothelial and smooth muscle cells (PASMCs) were cultured primarily, and they were divided into 4 groups: groups incubated under normoxia or hypoxia and those with or without treatment with 3,4-DHAP. The [Ca2+]i of both PAECs and PASMCs was measured by determining the fluorescence of fura 2 AM on spetrofluorometer. Our results showed that hypoxia caused significant elevation of [Ca2+]i, in both PAECs and PASMCs, 3,4-DHAP could attenuate the hypoxic elevation of [Ca2+]i only in PASMCs but not in PAECs. It is concluded that 3,4-DHAP decreases the hypoxic elevation of [Ca2+]i in PASMCs. This might contribute to its inhibitory effect on hypoxic pulmonary vasoconstriction.
Acetophenones ; pharmacology ; Animals ; Calcium ; metabolism ; Cell Hypoxia ; Cells, Cultured ; Endothelium, Vascular ; cytology ; metabolism ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Pulmonary Artery ; cytology ; metabolism ; Swine

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.
Animals ; Calcium ; metabolism ; Hypertension, Pulmonary ; chemically induced ; metabolism ; physiopathology ; Male ; Monocrotaline ; pharmacology ; Muscle, Smooth, Vascular ; cytology ; metabolism ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Pulmonary Artery ; cytology ; metabolism ; physiopathology ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; TRPC Cation Channels ; genetics ; metabolism