scholarly journals NO decreases phosphorylation of focal adhesion proteins via reduction of Ca in rat aortic smooth muscle cells

1998 ◽  
Vol 274 (5) ◽  
pp. H1613-H1619 ◽  
Author(s):  
Kuljeet Kaur ◽  
Jian Yao ◽  
Xiaolei Pan ◽  
Carolyn Matthews ◽  
Aviv Hassid

Our laboratory has previously reported that the antimitogenic effect of nitric oxide (NO) in primary cultures of rat aortic smooth muscle cells may be attributed to activation of protein tyrosine phosphatase and dephosphorylation of protein phosphotyrosine [G. S. Dhaunsi, C. Matthews, K. Kaur, and A. Hassid. Am. J. Physiol. 272 ( Heart Circ. Physiol. 41): H1342–H1349, 1997]. The goal of the current study was to investigate the role of cytoplasmic Ca in this process and to identify protein substrates that are dephosphorylated by treatment with NO. Treatment of primary rat aortic smooth muscle cell cultures with the NO donor S-nitroso- N-acetylpenicillamine (SNAP) decreased cytoplasmic Ca levels and elicited phosphotyrosine dephosphorylation. Both effects were mimicked by the extracellular and intracellular Ca chelators ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid (EGTA) and 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid (BAPTA), respectively, and by the Ca channel blocker nifedipine. Conversely, elevation of cytoplasmic Ca via the use of the Ca ionophore A-23187 or high extracellular K+prevented or attenuated SNAP-induced dephosphorylation. Both BAPTA and nifedipine also decreased DNA synthesis, providing further evidence to link dephosphorylation to antimitogenesis. Two of the proteins dephosphorylated by treatment of cells with NO or EGTA were identified as the focal adhesion proteins, cortactin and paxillin. These results indicate that NO-induced dephosphorylation of protein phosphotyrosine is mediated by reduction of cytoplasmic Ca and suggest that dephosphorylation of focal adhesion proteins may be of relevance to the antimitogenic effect of NO.

1992 ◽  
Vol 337 (1279) ◽  
pp. 37-47 ◽  

Smooth muscle cells from rat aorta were cultured in defined, serum-free medium and studied using whole-cell patch-clamp techniques. Under conditions designed to isolate currents through Ca channels, step depolarizations produced inward currents which were fast in onset and inactivated rapidly, with little sustained inward current being observed. Both Ni and Cd blocked these currents, with Ni being effective at 50 μM. Removal of external Na or addition of 1 μM tetrodotoxin had no effect. Peak inward currents were attained at about —15 mV, with half-maximal activation at —41 mV using —80 mV holding potentials. The transient inward currents were reduced by depolarized holding potentials, with half-maximal steady-state inactivation at —48 mV. In three of the 98 cells studied, small maintained inward currents were observed with a —40 mV holding potential. The Ca channel antagonist nicardipine (5 μM ) blocked the transient inward current while neither of the dihydropyridine Ca channel agonists S( + )202 791 and ( — )BAY K 8644 produced a significant augmentation of sustained inward current. At 10 μM, both noradrenaline and adrenaline but not phenylephrine decreased the peak inward current. This inhibition was unaffected by a variety of adrenoceptor antagonists and was also observed when internal solutions having high Ca buffering capacity were used, but was absent when GDP-β-S instead of GTP was included in the pipette solution. The main conclusions from this study are that under our cell culture conditions, rat aortic smooth muscle cells possess predominately a transient, low-threshold-activated inward Ca current and that this Ca current is inhibited by certain adrenoceptor agonists but with a quite atypical adrenoceptor antagonist pharmacology.


2018 ◽  
Vol 88 (5-6) ◽  
pp. 309-318
Author(s):  
Hae Seong Song ◽  
Jung-Eun Kwon ◽  
Hyun Jin Baek ◽  
Chang Won Kim ◽  
Hyelin Jeon ◽  
...  

Abstract. Sorghum bicolor L. Moench is widely grown all over the world for food and feed. The effects of sorghum extracts on general inflammation have been previously studied, but its anti-vascular inflammatory effects are unknown. Therefore, this study investigated the anti-vascular inflammation effects of sorghum extract (SBE) and fermented extract of sorghum (fSBE) on human aortic smooth muscle cells (HASMCs). After the cytotoxicity test of the sorghum extract, a series of experiments were conducted. The inhibition effects of SBE and fSBE on the inflammatory response and adhesion molecule expression were measured using treatment with tumor necrosis factor-α (TNF-α), a crucial promoter for the development of atherosclerotic lesions, on HASMCs. After TNF-α (10 ng/mL) treatment for 2 h, then SBE and fSBE (100 and 200 μg/mL) were applied for 12h. Western blotting analysis showed that the expression of vascular cell adhesion molecule-1 (VCAM-1) (2.4-fold) and cyclooxygenase-2 (COX-2) (6.7-fold) decreased, and heme oxygenase-1 (HO-1) (3.5-fold) increased compared to the TNF-α control when treated with 200 μg/mL fSBE (P<0.05). In addition, the fSBE significantly increased the expression of HO-1 and significantly decreased the expression of VCAM-1 and COX-2 compared to the TNF-α control in mRNA level (P<0.05). These reasons of results might be due to the increased concentrations of procyanidin B1 (about 6-fold) and C1 (about 30-fold) produced through fermentation with Aspergillus oryzae NK for 48 h, at 37 °C. Overall, the results demonstrated that fSBE enhanced the inhibition of the inflammatory response and adherent molecule expression in HASMCs.


Circulation ◽  
1997 ◽  
Vol 95 (7) ◽  
pp. 1954-1960 ◽  
Author(s):  
Mihaela Balica ◽  
Kristina Boström ◽  
Victoria Shin ◽  
Kirsten Tillisch ◽  
Linda L. Demer

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