Calcium channel regulation in vascular smooth muscle cells: synergistic effects of statins and calcium channel blockers.

In the Anglo-Scandinavian Cardiac Outcomes Trial-Lipid Lowering Arm (ASCOT-LLA) we have reported a positive interaction between atorvastatin and amlodipine-based antihypertensive strategy in terms of the prevention of coronary events. In cellular and molecular studies on human vascular smooth muscle cells (VSMC) we have reported that transformation from a differentiated to a synthetic or dedifferentiated phenotype is associated with loss of function of L-type calcium channels and hence loss of potential responsiveness to calcium channel blockers (CCB). Statins directly inhibit cell cycle progression and dedifferentiation of VSMC due to their ability to inhibit the synthesis of isoprenoid cholesterol intermediates.

Effect of serum withdrawal on the contribution of L-type calcium channels (CaV1.2) to intracellular Ca2+ responses and chemotaxis in cultured human vascular smooth muscle cells.

Vascular smooth muscle cell (VSMC) chemotaxis is fundamental to atherosclerosis and intimal hyperplasia. An increase in intracellular Ca2+ [Ca2+]i is an important signal in chemotaxis, but the role of L-type calcium channels (CaV1.2) in this response in human vascular smooth muscle cells (hVSMC) has not been examined.

PDGF stimulates DNA synthesis in human vascular smooth muscle cells via a novel wortmannin-insensitive phosphatidylinositol 3-kinase.

The class 1(A) phosphatidylinositol 3-kinase enzymes consist of a number of heterodimeric complexes of regulatory and catalytic subunits and have been implicated in a number of cellular responses. While platelet-derived growth factor (PDGF)-induced chemotaxis of human vascular smooth muscle cells (HVSMC) is inhibited by both wortmannin and LY294002, DNA synthesis is only inhibited by LY294002. Serum-induced DNA synthesis however is inhibited by LY294002, wortmannin and rapamycin.

Thrombospondin-1 differentially induces chemotaxis and DNA synthesis of human venous smooth muscle cells at the receptor-binding level.

Thrombospondin-1 is a large matricellular protein that acts as a pleiotropic growth factor for human vascular smooth muscle cells, and may play a role in the progression of vascular disease. Although we have previously demonstrated the dependence of both thrombospondin-1-stimulated cell chemotaxis and proliferation on tyrosine kinases, the receptor mechanisms involved remain obscure. This investigation aims to determine the nature of the receptor(s) involved in the cellular responses to thrombospondin-1.

Action of an HMG CoA reductase inhibitor, lovastatin, on apoptosis of untransformed and ts-SV40 transformed human smooth muscle cells derived from saphenous vein.

The effect of lovastatin, an inhibitor of 3-hydroxymethyl-3-glutaryl coenzyme A (HMG CoA) reductase, was examined on human vascular smooth muscle cells (HVSMC). Untransformed HVSMC were obtained from saphenous vein and in addition an SV-40 transformed immortalized cell line (HVTs-SM1) derived from saphenous vein smooth muscle was also used. HVTs-SM1 cell proliferation and DNA synthesis were measured, and cell cycle analysis was performed by flow cytometry.

p53, p21(WAF1/CIP1), and MDM2 involvement in the proliferation and apoptosis in an in vitro model of conditionally immortalized human vascular smooth muscle cells.

Using an in vitro model of a conditionally immortalized cell line, we have investigated how human vascular smooth muscle cells (VSMCs) are affected by the expression of simian virus 40 (SV40) large T antigen (LT antigen), which binds to cell cycle regulators such as the tumor suppressor protein p53. Cells were obtained after infection of saphenous vein-derived VSMCs with a nonreplicative retroviral vector containing a temperature-sensitive mutant of SV40 LT antigen and were shown to have maintained some characteristics and responses of VSMCs. Under permissive-temperature conditions (36 degrees C), the increased rate of cell proliferation was shown to be associated with expression of LT antigen and with LT antigen binding to and inactivation of p53.

p53, p21(WAF1/CIP1), and MDM2 involvement in proliferation and apoptosis in an in vitro model of conditionally immortalized human vascular smooth muscle cells.

Using an in vitro model of a conditionally immortalized cell line, we investigated how human vascular smooth muscle cells (VSMCs) are affected by the expression of simian virus 40 (SV40) large T antigen (LT antigen), which binds to cell cycle regulators, such as the tumor suppressor protein p53. Cells were obtained after infection of saphenous vein-derived VSMCs with a nonreplicative retroviral vector containing a temperature-sensitive (ts) mutant of SV40 LT antigen and were shown to have maintained some characteristics and responses of VSMCs. Under permissive temperature conditions (36 degrees C), the increased rate of cell proliferation was shown to be associated with expression of LT antigen and with LT-antigen binding to and inactivation of p53.

Effect of hypercholesterolaemia on voltage-operated calcium channel currents in rabbit arterial smooth muscle cells.

Cholesterol is a major component of cell membranes and influences membrane fluidity. Watanabe heritable hyperpercholesterolaemic rabbits (WHHL) possess defective receptors for low density lipoprotein leading to increased plasma cholesterol, accumulation of cholesterol in the arterial wall and atherosclerosis. In this study calcium channel currents (IBa) were compared using conventional whole cell voltage clamp techniques in ear artery cells isolated from control New Zealand White rabbits (NZ) with those from WHHL.

Phosphatidylinositol 3-kinase and focal adhesion kinase are early signals in the growth factor-like responses to thrombospondin-1 seen in human vascular smooth muscle.

Thrombospondin-1 (TSP-1) is a matricellular protein that is expressed in negligible amounts in normal blood vessels but is markedly upregulated in vascular injury. Although TSP-1 can act as a pleiotropic regulator for human vascular smooth muscle cells (HVSMCs), the intracellular signaling pathways stimulated by this protein remain obscure. In cultured HVSMCs derived from saphenous vein, TSP-1 induces tyrosine phosphorylation of a number of cellular proteins, with a complex temporal pattern of activation.

Role of intracellular calcium ([Ca2+]i) and tyrosine phosphorylation in adhesion of cultured vascular smooth muscle cells to fibrinogen.

Objective: Fibrinogen is an independent risk factor for cardiovascular disease. This study has investigated the role of intracellular Ca2+ ([Ca2+]i) and tyrosine phosphorylation in the attachment of human and rat-derived cultured vascular smooth muscle cells to fibrinogen.

Methods: Cells were cultured from human saphenous vein segments (HVSMC) and from an established rat aortic cell line (A7r5).

Platelet-derived growth factor beta-receptors can both promote and inhibit chemotaxis in human vascular smooth muscle cells.

The effect of the three platelet-derived growth factor (PDGF) isoforms AA, AB, and BB on migration was investigated in cultured human saphenous vein smooth muscle cells. The modified Boyden chamber technique yielded efficacies BB >> AB, AA = 0. However, the BB concentration-response relationship displayed a pronounced peak, occurring between 1 and 10 ng/mL, with no response above this range.

Thrombospondin-1 is a potent mitogen and chemoattractant for human vascular smooth muscle cells.

Thrombospondin-1 (TSP-1) is a matricellular protein that is present in negligible amounts in normal human vasculature but occurs in significant amounts in diseased vessels. In this study, we examined the effect of TSP-1 on DNA synthesis, proliferation, and migration in human vascular smooth muscle cells grown from saphenous vein. TSP-1 (0.

Differential effects of lovastatin on mitogen induced calcium influx in human cultured vascular smooth muscle cells.

1. In this study the effect of lovastatin, an inhibitor of cholesterol and isoprenoid synthesis, on the rises in intracellular calcium concentration ([Ca2+]i) induced by platelet derived growth factor BB (PDGF-BB), angiotensin II (AII), low density lipoproteins (LDL) and foetal calf serum (FCS) was examined in human cultured vascular smooth muscle cells (VSMC) from saphenous vein. Changes in [Ca2+]i were measured in cell suspensions by the Ca2+ sensitive probe, fura 2.

Platelet-derived growth factor (PDGF): actions and mechanisms in vascular smooth muscle.

1. PDGF is a highly hydrophilic cationic glycoprotein (M(r) 28-35kDa) produced by platelets, monocyte/macrophages, endothelial cells and vascular smooth muscle cells under some conditions. 2.

Effect of angiotension II on the expression of the early growth response gene c-fos and DNA synthesis in human vascular smooth muscle cells.

Objectives: The aims of this study were to characterize the angiotensin II receptor subtype present on vascular smooth muscle cells from human saphenous vein and to assess the effect of angiotensin II on the expression of the early growth response gene c-fos and on DNA synthesis.

Methods And Results: Using radioligand binding studies, we have defined the angiotensin II receptors present on these cells as being predominantly of the AT1 subtype. Angiotensin II increased peak intracellular calcium levels by 126 +/- 16 nmol/l (mean +/- SEM) in 17/49 cultures.

Comparison of effects of platelet-derived growth factor isoforms on signaling and DNA synthesis of human cultured saphenous vein cells.

We examined the effect of platelet-derived growth factor (PDGF)-AA, PDGF-AB, and PDGF-BB isoforms on DNA synthesis, Ca2+ mobilization, and tyrosine phosphorylation in cultured human saphenous vein cells cultured by an explant technique; confluent cells derived from passage 3 were used for all studies. DNA synthesis was measured by [methyl3H]thymidine uptake, intracellular [Ca2+] ([Ca2+]i) was measured with the Ca(2+)-sensitive indicator fura-2, and tyrosine phosphorylation was measured by Western blotting techniques. All three isoforms of PDGF stimulated [methyl3H]thymidine uptake concentration dependently, with similar potency.

Inhibition of human vascular smooth muscle cell proliferation by lovastatin: the role of isoprenoid intermediates of cholesterol synthesis.

Restenosis remains the largest single obstacle to the long-term success of invasive vascular interventions. Lovastatin, an HMG-CoA reductase inhibitor, has been shown to reduce myointimal hyperplasia in animal models of restenosis and in one clinical coronary restenosis trial. We have assessed the effect of lovastatin on the growth of cultured human vascular smooth muscle cells derived from saphenous vein and vascular graft stenoses.