Background-Rho-associated kinase (ROCK), an effector of small GTPase Rho, regulates vascular tone via a calcium sensitization mechanism and plays a key role in the pathogenesis of hypertension. However, its role in vascular growth remains unclear. Methods and Results-Y-27632, a specific ROCK inhibitor, and the overexpression of dominant-negative ROCK suppressed the mitogen-induced DNA synthesis of cultured vascular smooth muscle cells (VSMCs), which indicates the essential role of ROCK in the control of VSMC proliferation in vitro. Y-27632 also suppressed the chemotaxis of VSMCs. Male Wistar rats were systemically given Y-27632 (35 to 70 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 ) through an intraperitoneal infusion. The neointimal formation of balloon-injured carotid arteries was significantly suppressed in Y-27632-treated rats (intima/media ratio, 0.22Ϯ0.02) compared with vehicle-treated rats (intima/media ratio, 0.92Ϯ0.21) or hydralazine-treated rats with a similar blood pressure decrease (intima/media ratio, 1.03Ϯ0.15). The phosphorylation of myosin phosphatase and myosin light chain was elevated in injured arteries in a Y-27632-sensitive manner, indicating the augmentation of ROCK activity in neointimal formation. The downregulation of the cyclin-dependent kinase inhibitor p27 kip1 in injured vessels was reversed by Y-27632 treatment, reflecting the antiproliferative effect of ROCK inhibition in vivo. Conclusions-We conclude that ROCK plays a key role in the process of neointimal formation after balloon injury. Thus, the inhibition of ROCK may be a potential therapeutic strategy for treating vascular proliferative disorders and hypertension. Key Words: atherosclerosis Ⅲ muscle, smooth Ⅲ remodeling Ⅲ signal transduction Ⅲ hypertension E levated vascular tone contributes to the pathogenesis of hypertension. Rho-associated kinase (ROCK), 1 a target of small GTPase Rho, regulates vascular contractility by increasing the level of phosphorylated myosin light chain and thereby elevating the calcium sensitivity of vascular smooth muscle cells (VSMCs). 2 Recently, Uehata et al 3 developed a potent, specific, ROCK inhibitor, Y-27632. The administration of Y-27632 to several hypertensive rat models markedly reduced systolic blood pressure (SBP), implicating ROCK as a key mediator in the pathogenesis of hypertension. 3 We and others have reported that regulators of vascular tone, such as angiotensin II or natriuretic peptides, are also involved in vascular growth. 4 Thus, we postulated that intracellular mechanism(s) should exist that govern both vascular contraction and growth. Using Y-27632 and dominant-negative ROCK, the present study demonstrates that ROCK, the key regulator of vascular contraction, also controls vascular growth in vitro and in vivo. Methods MaterialsY-27632 was obtained from Yoshitomi Pharmaceutical Industries, Osaka, Japan. The pCAG-myc and pCAG-myc-KD-IA plasmids 1 were a gift from T. Ishizaki and S. Narumiya (Kyoto University). The pEXV-myc-N19RhoA was from M. Symons (the Picower Institute for Medical Research), and...

Abstract-Vascular endothelial growth factor

No abstract

Impairment of insulin action (insulin resistance) is frequently observed in Type II (non-insulin-dependent) diabetes mellitus as well as in wasting syndromes including neoplastic, inflammatory and chronically infectious diseases [1,2]. Previous studies suggest that inflammatory cytokines, such as tumour necrosis factor-a (TNF-a) [3], interleukin-1 (IL-1) [4], , leukaemia inhibitory factor (LIF) [6] and transforming growth factor-b (TGF-b) [7] are involved in the development of insulin resistance. Clinical studies have shown that TNF-a and IL-6 concentrations are increased in the sera of patients with several cancers and infectious diseases, in which insulin action is impaired [8]. Moreover, infusion of rats Diabetologia (1999) Abstract Aims/hypothesis. Previous studies show that inflammatory cytokines play a part in the development of insulin resistance. Thiazolidinediones were developed as insulin-sensitizing drugs and are ligands for the peroxisome proliferator-activated receptorg (PPARg). We hypothesized that the anti-diabetic mechanism of thiazolidinediones depends on the quantity of PPARg in the insulin resistant state in which inflammatory cytokines play a part. Methods. We isolated rat PPARg1 and g2 cDNAs and examined effects of various cytokines and thiazolidinediones on PPARg mRNA expression in rat mature adipocytes. Results. Various inflammatory cytokines, such as tumour necrosis factor-a (TNF-a), interleukin-1a (IL1a), IL-1b, IL-6 and leukaemia inhibitory factor decreased PPARg mRNA expression. In addition, hydrogen peroxide, lysophosphatidylcholine or phorbol 12-myristate 13-acetate also decreased the expression of PPARg. The suppression of PPARg mRNA expression caused by 10 nmol/l of TNF-a was reversed 60 % and 55 % by treatment with 10 ±4 mol/l of troglitazone and 10 ±4 mol/l of pioglitazone, respectively. The suppression of glucose transporter 4 mRNA expression caused by TNF-a was also reversed by thiazolidinediones. Associated with the change of PPARg mRNA expression, troglitazone improved glucose uptake suppressed by TNF-a. Conclusion/interpretation. Our study suggests that inflammatory cytokines could be factors that regulate PPARg expression for possible modulation of insulin resistance. In addition, we speculate that the regulation of PPARg mRNA expression may contribute to the anti-diabetic mechanism of thiazolidinediones. [Diabetologia (1999) 42: 702±710]

Abstract-We recently reported that C-type natriuretic peptide (CNP) occurs in vascular endothelial cells and acts as a vascular-type natriuretic peptide. In the present study, we stimulated the cGMP cascade in proliferating smooth muscle cells (SMCs), in which particulate guanylate cyclase-B, the specific receptor for CNP, is predominantly expressed, by use of an adenovirus encoding rat CNP cDNA (Ad.CNP). In the Ad.CNP-treated cultured SMCs, CNP caused the growth inhibition of SMCs at G 1 phase with an early increase of p21 CIP1/WAF1 expression and subsequent upregulation of p16 INK4a . The expression of smooth muscle myosin heavy chain-2, which is the molecular marker of highly differentiated SMCs, was reinduced in the Ad.CNP-treated SMCs. The Ad.CNP-treated SMCs also reexpressed particulate guanylate cyclase-A, which shows high affinity to atrial and brain natriuretic peptide and is exclusively expressed in well-differentiated SMCs. CNP, which was overexpressed in rabbit femoral arteries in vivo at the time of balloon injury, significantly suppressed neointimal formation. Furthermore, an enhancement of the expression of smooth muscle myosin heavy chain-2 occurred in the residual neointima. In addition, early regeneration of endothelial cells was observed in the Ad.CNP-infected group. The natriuretic peptide family consists of atrial, brain, and C-type natriuretic peptides (ANP, BNP, and CNP, respectively), which act as vasodilators and growth inhibitors of vascular smooth muscle cells (SMCs). 1,2 These peptides elicit their biological effects via the elevation of intracellular cGMP by activating 2 biologically active natriuretic peptide receptors, namely, membrane-bound guanylate cyclase-A (GC-A) and guanylate cyclase-B (GC-B). We and others have demonstrated that ANP and BNP show high affinity to GC-A, whereas CNP selectively binds to 4 Although ANP and BNP are cardiac hormones secreted mainly from the atrium and the ventricle of the heart, respectively, we have demonstrated that CNP is produced in and secreted from vascular endothelial cells (ECs) 5 to act as a local regulator of vascular tone and growth. 6,7 We have also revealed that the endothelial secretion of CNP is stimulated by various cytokines and growth factors that are produced and activated in proliferative vascular lesions, especially transforming growth factor-␤ and tumor necrosis factor-␣. 5,8 In the pathogenesis of proliferative vascular lesions, alteration of differentiation of SMCs (from the "contractile" to "synthetic" phenotype) is considered to be important. 9 We