A new SOBP-formation method by superposing specially shaped Bragg curves formed by a mini-ridge filter for spot scanning in proton beam therapy.

PURPOSE: We propose a new spread-out Bragg peak (SOBP) formation method for low-energy regions of spot-scanning proton therapy in order to reduce the required number of energy layers while maintaining high dose uniformity, while maintaining the distal falloff as sharp as possible. METHODS: We use only one specially shaped mini-ridge filter (MRF) to create new trapezoidal Bragg curves (TBCs) from very sharp pristine Bragg curves (PBCs) of low-energy proton beams. The TBC has three pre-designed dose regions of proximal, flat-top, and distal components. These components are designed to have nearly equal depth lengths and good linearity. Then, the required SOBP is formed by superposing the TBCs with the correct spacing and beam intensity weights. We then compare the performance of the TBC-based SOBPs with those formed by PBCs. RESULTS: The dose uniformities of the SOBP formed by the proposed method are kept within the design tolerance, and are equivalent to those of conventional SOBPs. The sharpness of the distal falloff is reasonably kept by the deepest TBC. The required number of energy layers is significantly reduced compared with that of conventional PBC-based SOBP. CONCLUSIONS: The proposed method enables shortening of the irradiation time of spot-scanning proton beam therapy in low-energy regions with a reduced number of energy layers. It can be realized by using only one specially shaped MRF, which can be easily installed at any facility.

Measurement of psychological state changes at low dopamine transporter occupancy following a clinical dose of mazindol.

RATIONALE: The beneficial effects of psychostimulant drugs in the treatment of psychiatric disorders occur because they increase the extracellular dopamine concentration by inhibiting re-uptake of extracellular dopamine at dopamine transporters. However, the psychological effects at low dopamine transporter occupancy have not been well demonstrated. OBJECTIVES: The purpose of the study was to evaluate the psychological effects, dopamine transporter occupancy, and dopamine release induced by a single oral administration of a clinical dose of mazindol. METHODS: Ten healthy male volunteers were orally administered a placebo and a clinical dose of mazindol (1.5 mg) on separate days. The psychological effects of mazindol were assessed using a visual analogue scale to detect alterations in the state of consciousness. The amount of blockade of dopamine transporters was assessed using positron emission tomography with [18F]FE-PE2I and extracellular dopamine release was measured as the amount of change in [11C]raclopride binding. RESULTS: Following administration of a clinical dose of mazindol, the dopamine transporters were blocked by 24-25 %, and the binding potential of [11C]raclopride was reduced by 2.8-4.6 %. The differences of a score measuring derealisation and depersonalization associated with a positive basic mood were significantly correlated with the change in the [11C]raclopride binding in the limbic striatum. CONCLUSIONS: A subtle alteration in the state of consciousness was detected with a correlation to the changes in the [11C]raclopride binding, which implies that a subtle alteration in extracellular dopamine concentration in the limbic striatum by a small amount of dopamine transporter occupancy can affect the state of consciousness. TRIAL REGISTRATION HTTPS://UPLOAD.UMIN.AC.JP/CGI-OPEN-BIN/CTR_E/CTR_VIEW.CGI?RECPTNO=R000009703 : UMIN000008232.

Clinical evaluation of autologous gamma delta T cell-based immunotherapy for metastatic solid tumours.

BACKGROUND: Adoptive transfer of ex vivo expanded autologous Vγ9Vδ2 T cells may be of therapeutic benefit for cancer because of their potent direct cytotoxicity towards tumour cells, synergistic cytotoxicity when combined with aminobisphosphonates and enhancement of antibody-dependent cell-mediated cytotoxicity. METHODS: To determine the feasibility and clinical safety of therapy with ex vivo expanded, activated Vγ9Vδ2 T cells in combination with zoledronate, we enrolled 18 subjects with advanced solid tumours into a phase I clinical study. Administered indium(111)-oxine-labelled Vγ9Vδ2 T cells were tracked in a cohort of patients. RESULTS: Administered Vγ9Vδ2 T cells had an activated effector memory phenotype, expressed chemokine receptors predictive of homing to peripheral tissues and were cytotoxic in vitro against tumour targets. Adoptively transferred Vγ9Vδ2 T cells trafficked predominantly to the lungs, liver and spleen and, in some patients, to metastatic tumour sites outside these organs. No dose-limiting toxicity was observed, but most patients progressed on study therapy. However, three patients administered Vγ9Vδ2 T cells while continuing previously ineffective therapy had disease responses, suggesting an additive effect. CONCLUSION: Therapy with aminobisphosphonate-activated Vγ9Vδ2 T cells is feasible and well tolerated, but therapeutic benefits appear only likely when used in combination with other therapies.

Bifurcation phenomena in the optimal velocity model for traffic flow.

In the optimal velocity model with a time lag, we show that there appear multiple exact solutions in some ranges of car density, describing a metastable uniform flow, a metastable congested flow, and an unstable congested flow. This establishes the presence of subcritical Hopf bifurcations. Our analytical results have implications for continuum traffic flow, such as hysteresis phenomena associated with discontinuous transitions between uniform and congested flow.

[A case of stunned myocardium concomitant with endotracheal intubation].

"Stunned myocardium" was defined by Braunwald et al in 1982 as reversible postischemic myocardial dysfunction. We report a case of a 57-year-old woman for cholesystectomy who developed stunned myocardium during endotracheal intubation. She was free of any risks of heart disease. While the endotracheal tube was smoothly inserted after rapid induction, the blood pressure was remarkably elevated and electrocardiogram (ECG) showed ST segment elevations in leads I, aVL, as well as V2-V6, and ST segment depressions in leads II, III and aVF. The coronary angiography, performed 2 weeks later, revealed a normal coronary finding, but the left ventriculogram showed asynergy in its anterior and apical walls (AHA segments 2, 3 and 6). Left ventricular dysfunction in this case was possibly due to a direct effect of excessive cathecholamines secreted during an acute episode of hypertension triggered by intubation.

Plasma levels of nitric oxide and related vasoactive factors following long-term treatment with angiotensin-converting enzyme inhibitor in patients with essential hypertension.

Several mechanisms other than the inhibition of systemic and local formation of angiotensin II (Ang II) have been proposed to play a role in mediating the hypotensive effects of angiotensin-converting enzyme (ACE) inhibitors. In the present study, we measured plasma levels of nitric oxide (NO) and the related vasoactive factors bradykinin, 6-keto prostaglandin F1alpha (6-keto PGF1alpha) a stable metabolite of prostacyclin, and cyclic guanosine-3',5'-monophosphate (cGMP) before and after a 4-week treatment with the ACE inhibitor lisinopril in 17 patients with essential hypertension. Plasma NO levels were measured by the Griess method after conversion of nitrate to nitrite. Long-term lisinopril treatment significantly reduced blood pressure and increased plasma NO and 6-keto PGF1alpha. The treatment also tended to increase plasma levels of bradykinin and cGMP, but not to a significant extent. The posttreatment NO level was inversely correlated with posttreatment systolic, diastolic, and mean blood pressure (n = 17, r= -.68, P< .01, n = 17, r= -.54, P < .05, and n = 17, r= -.66, P< .01, respectively). The posttreatment bradykinin level was also modestly correlated with posttreatment systolic and mean blood pressure (n = 17, r = -.51, P < .05 and n = 17, r = -.55, P < .05, respectively). In contrast, posttreatment 6-keto PGF1alpha and cGMP levels were not correlated with posttreatment systolic, diastolic, or mean blood pressure. These findings raise the possibility that increased formation of NO and bradykinin, as well as inhibition of the renin-angiotensin system, contribute to the hypotensive effect of the ACE inhibitor observed in our hypertensive patients.

Association between angiotensin-converting enzyme gene polymorphisms and regression of left ventricular hypertrophy in patients treated with angiotensin-converting enzyme inhibitors.

PURPOSE: An insertion/deletion (ID) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with left ventricular hypertrophy. The present study examined polymorphisms of the ACE gene in patients with essential hypertension and left ventricular hypertrophy who were participants in a long-term trial of therapy with an ACE inhibitor. PATIENTS AND METHODS: ACE inhibitor therapy was administered for >2 years to 54 patients with hypertension who had moderate or severe left ventricular hypertrophy. Cardiac dimensions were monitored by echocardiography before the initiation of therapy and after 1 and 2 years of treatment. Serum ACE activity and plasma concentrations of brain natriuretic peptide, a marker for left ventricular hypertrophy, were also monitored. RESULTS: Eighteen patients had the II genotype for the angiotensin-converting enzyme gene, 19 had the ID genotype, and 17 had the DD genotype. Baseline (mean +/- SD) serum ACE activity was significantly greater (P <0.05) in the DD (18 +/- 7 IU/L) group than in the II (7 +/- 4 IU/L) or ID (12 +/- 6 IU/L) groups. ACE inhibitor therapy was effective in controlling blood pressure, and it reduced posterior and septal wall thickness, left ventricular mass index, and plasma brain natriuretic peptide concentration in all three groups. Despite similar blood pressure reductions, after 2 years, mean (+/- SD) regression in posterior wall thickness was significantly less (P <0.05) in the DD group (-9% +/- 5%) than in the ID (-21% +/- 7%) and II (-21% +/- 9%) groups. Similar results were seen for the reductions in brain natriuretic peptide levels. The magnitudes of regression of septal wall thickness and left ventricular mass index during therapy were less in the DD group than the II group (P <0.05). CONCLUSION: Hypertensive patients with the DD genotype are less likely to have regression of left ventricular hypertrophy when treated with ACE inhibitors than are patients with other ACE genotypes.

Antioxidants improve impaired insulin-mediated glucose uptake and prevent migration and proliferation of cultured rabbit coronary smooth muscle cells induced by high glucose.

BACKGROUND: To explore the role of intracellular oxidative stress in high glucose-induced atherogenesis, we examined the effect of probucol and/or alpha-tocopherol on the migration and growth characteristics of cultured rabbit coronary vascular smooth muscle cells (VSMCs). METHODS AND RESULTS: Chronic high-glucose-medium (22. 2 mmol/L) treatment increased platelet-derived growth factor (PDGF)-BB-mediated VSMC migration, [3H]thymidine incorporation, and cell number compared with VSMCs treated with normal-glucose medium (5.6 mmol/L+16.6 mmol/L mannose). Probucol and alpha-tocopherol significantly suppressed high glucose-induced increase in VSMC migration, cell number, and [3H]thymidine incorporation. Probucol and alpha-tocopherol suppressed high glucose-induced elevation of the cytosolic ratio of NADH/NAD+, phospholipase D, and membrane-bound protein kinase C activation. Probucol, alpha-tocopherol, and calphostin C improved the high glucose-induced suppression of insulin-mediated [3H]deoxyglucose uptake. Chronic high-glucose treatment increased the oxidative stress, which was significantly suppressed by probucol, alpha-tocopherol, suramin, and calphostin C. CONCLUSIONS: These findings suggest that probucol and alpha-tocopherol may suppress high glucose-induced VSMC migration and proliferation via suppression of increases in the cytosolic ratio of free NADH/NAD+, phospholipase D, and protein kinase C activation induced by high glucose, which result in reduction in intracellular oxidative stress.

Heparin inhibits human coronary artery smooth muscle cell migration.

Heparin, an anticoagulant, has been shown to reduce neointimal proliferation and restenosis following vascular injury in experimental studies, but the clinical trials of heparin in coronary balloon angioplasty have been negative. The current study, therefore, examined the effect of heparin on basal or stimulated migration by serum and platelet-derived growth factor (PDGF)-BB in cultured human coronary artery smooth muscle cells (SMCs) by Boyden's chamber method. In addition, the reversibility of the heparin effect on human coronary artery SMC migration was examined. Fetal calf serum (FCS) and PDGF-BB stimulated SMC migration in a concentration-dependent manner. Heparin in moderate to high concentration (10 to 100 U/mL) exhibited concentration-related inhibition of FCS- and PDGF-BB-stimulated SMC migration; however, a low concentration (1 U/mL) of heparin had no inhibitory effects. Heparin also had weak inhibitory effects on nonstimulated SMC migration. The SMCs that were exposed to a high concentration (100 U/mL) of heparin for 6 hours were capable of migrating after a short lag period of removal of heparin from the culture medium. These SMCs also showed recovery of responses to FCS and PDGF-BB by migrating significantly greater than the nonstimulated level. Furthermore, heparin-containing medium did not contain detached cells. These results indicate that heparin inhibits human coronary artery SMC migration, especially when stimulated by FCS or PDGF-BB, and that this inhibitory effect of heparin is reversible and not simply a function of killing cells.

Induction by lysophosphatidylcholine, a major phospholipid component of atherogenic lipoproteins, of human coronary artery smooth muscle cell migration.

BACKGROUND: The objectives of the present study were (1) to determine whether lysophosphatidylcholine (lyso-PC), a prominent component of oxidatively modified LDL, induces migration of human coronary artery smooth muscle cells (SMCs) and, if so, to clarify the mechanism, and (2) to investigate the possible interactions of lyso-PC and platelet-derived growth factor (PDGF)-BB, endothelin- (ET-1), adrenomedullin (AM), or vitamin E on SMC migration by the Boyden's chamber method. METHODS AND RESULTS: Lyso-PC induced SMC migration in a concentration-dependent manner between 10(-6) and 5 x 10(-5) mol/L. By contrast, phosphatidylcholine was without significant activity, and lysophosphatidylinositol and lysophosphatidylserine were much less effective than lyso-PC. Lyso-PC increased basic fibroblast growth factor (bFGF) production in a concentration-dependent manner between 10(-6) and 5 x 10(-5) mol/L in these cells. Furthermore, lyso-PC-induced SMC migration was inhibited by neutralizing antibody to bFGF but not by neutralizing antibody to transforming growth factor-beta1. Lyso-PC-induced migration was significantly enhanced by PDGF-BB or ET-1 but was clearly inhibited by human AM and vitamin E. CONCLUSIONS: These results indicate that (1) lyso-PC induces human coronary artery SMC migration at least in part through release of endogenous bFGF and (2) this lyso-PC-induced migration can be further induced by PDGF-BB and ET-1 and can be inhibited by human AM and vitamin E. Lyso-PC may recruit medial SMCs during the process of coronary atherosclerosis in part by releasing bFGF in concert with PDGF-BB or ET-1 in vascular tissues. This lyso-PC-induced SMC migration may be suppressed by AM and vitamin E under certain pathological conditions.

Effect of the endothelin family of peptides on human coronary artery smooth-muscle cell migration.

The migration of coronary artery medial smooth-muscle cells (SMCs) is one of the key events in the process of intimal thickening in coronary atherosclerotic lesions. The objectives of the present study were to determine whether any of the three isoforms of endothelin (ET), ET-1, ET-2, and ET-3, or an intermediate form of ET, big ET-1, induces migration of human coronary artery SMCs, and to investigate the possible interaction of ET peptides and well-known migration-stimulatory factors, platelet-derived growth factor (PDGF)-BB and angiotensin II (Ang II), on SMC migration by the Boyden's chamber method. None of the ET peptides alone induced SMC migration between 10(-9) and 10(-7) mol/L. In contrast, ET-1 and ET-2 significantly induced SMC migration in the presence of low concentrations of PDGF-BB (0.5 ng/mL) or Ang II (10(-9) mol/L), although ET-3 was less active (ET-1 = ET-2 > ET-3). In contrast, big ET-1 was without significant activity on PDGF-BB-or Ang II-induced SMC migration. The potentiation of SMC migration by ET peptides was clearly inhibited by the ETA receptor antagonist BG-123 in a concentration-dependent manner. These results suggest that the ET family of peptides, especially ET-1 and ET-2, can induce human coronary artery SMC migration in combination with PDGF-BB or Ang II, probably via ETA receptors. Taken together with the finding that the concentrations of ET, PDGF-BB and Ang II are locally increased at sites of endothelial injury, this indicates that ET may be an initial stimulus for human coronary artery medial SMC recruitment during coronary atherosclerosis, possibly in combination with PDGF-BB or Ang II.

Heparin suppresses cyclosporine-induced endothelin-1 synthesis in rat endothelial cells.

Cyclosporine stimulates vasoconstrictor endothelin-1 (ET-1) synthesis. This study examined the effect of heparin on cyclosporine-induced ET-1 synthesis in Wistar rat aortic endothelial cells in culture. Cyclosporine (0.01-5 mumol/L) stimulated ET-1 mRNA expression in a dose-dependent manner. A nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA) (10(-5) mol/L), did not affect cyclosporine-induced ET-1 mRNA expression. Heparin (1-20 U/ml) suppressed cyclosporine-induced ET-1 mRNA expression in a dose-dependent manner. The inhibitory effect of heparin was blunted in the presence of either L-NMMA (10(-5) mol/L) or calmodulin inhibitors such as N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) (5 x 10(-5) mol/L) or calmidazolium (5 x 10(-5) mol/L) in the presence of the phosphodiesterase inhibitor 3-isobutyl 1-methylxanthine (0.1 mmol/L). These results suggest that heparin suppresses cyclosporine-induced ET-1 mRNA expression via both NO- and calmodulin-dependent pathways.

Suppression of endothelin-3-induced nitric oxide synthesis by triglyceride in human endothelial cells.

Reduced endothelium-derived nitric oxide (NO) production characterizes several vascular diseases. This study examined the effect of triglyceride on NO production induced by endothelin-3 (ET-3) in cultured human umbilical vein endothelial cells. Triglyceride-rich human plasma obtained after a high-carbohydrate diet with white wine was used in an ex vivo study. The plasma triglyceride fraction was found to consist of large amounts of palmitic and oleic acids detected by gas-liquid chromatography. Therefore, the effect of synthetic tripalmitin and triolein emulsion on NO production was also examined. ET-3 stimulated NO and guanosine 3',5'-cyclic monophosphate production and increased cytosolic Ca2+ levels in the endothelial cells (ECs). After incubation of the ECs with the triglyceride-rich plasma for 2 h, these responses to ET-3 were ameliorated in a triglyceride concentration-dependent manner (50-200 mg/dl). A synthesized emulsion of tripalmitin (100 mg/dl) and triolein (100 mg/dl) also blunted the responses to ET-3. Neither endothelial constitutive NO synthase mRNA expression nor its protein level was affected by treatment with triglycerides. These results suggest that triglyceride suppresses ET-3-induced NO synthesis in human ECs by inhibiting cytosolic Ca2+ elevation.

Functional anatomy of gliding membrane muscles in the sugar glider (Petaurus breviceps).

In order to clarify the morphological adaptation for gliding behavior in the marsupial mammals, the gliding membrane muscles in the sugar glider (Petaurus breviceps) were observed. Unlike the styliform cartilage in flying squirrels, the sugar glider has a well-developed tibiocarpalis muscle in the most lateral area of the gliding membrane. The gliding membrane substantially consists of the humerodorsalis and tibioabdominalis muscle complex. We believe that the thick tibiocarpalis bundle and the humerodorsalis and tibioabdominalis muscle complex may serve as a membrane controller in the gliding behavior. A characteristic thin membranous structure between the cutaneous and deeper muscles was observed. In addition to the direct powerful control exerted by trunk and limb movement, we suggest that indirect power conduction by this thin membranous structure may contribute to gliding membrane control.

Mechanisms of action of troglitazone in the prevention of high glucose-induced migration and proliferation of cultured coronary smooth muscle cells.

Recent findings suggest that high glucose levels may promote atherosclerosis in coronary vascular smooth muscle cells (VSMCs). To explore the intracellular mechanisms of action by which troglitazone affects this process, we examined the effect of troglitazone on the migration and growth characteristics of cultured rabbit coronary VSMCs. Treatment with chronic high glucose medium (22.2 mmol/L) for 5 days increased VSMC migration by 92%, [3H]thymidine incorporation by 135%, and cell number by 32% compared with VSMCs treated with normal glucose (5.5 mmol/L glucose + 16.6 mmol/L mannose) medium. Trolitazone at 100 nmol/L and 1 mumol/L significantly suppressed high glucose-induced VSMC migration by 34% and 42%, respectively, the proliferative effect (as measured by cell number) by 17% and 27%, and [3H]thymidine incorporation by 45% and 60% (n = 6, P < .05). The high glucose-induced impairment of insulin-mediated [3H]deoxyglucose uptake was blocked by a protein kinase C (PKC) inhibitor (calphostin C, 1 mumol/L) and was also improved by troglitazone without any change in insulin receptor number and affinity. The high glucose-induced insulin-mediated increase in cell number and in [3H]thymidine incorporation was suppressed by troglitazone. Troglitazone (1 mumol/L) also suppressed high glucose-induced phospholipase D activation, elevation of the cytosolic NADH/NAD+ ratio (as measured by the cytosolic ratio of lactate/pyruvate), and membrane-bound PKC activation. Flow cytometric DNA histogram analysis of cell cycle stage showed that high glucose-induced increase in the percentage of cells in the S phase was suppressed by 1 mumol/L troglitazone. These findings suggest that PKC may be a link between impairment of insulin-mediated glucose uptake and the increase in migration and proliferation induced by high glucose levels and that troglitazone may be clinically useful for the treatment of high glucose-induced coronary atherosclerosis.

Dopamine as a novel antimigration and antiproliferative factor of vascular smooth muscle cells through dopamine D1-like receptors.

Vascular smooth muscle cell (VSMC) migration and proliferation are believed to play key roles in atherosclerosis. To elucidate the role of vascular dopamine D1-like receptors in atherosclerosis, the effects of dopamine and specific D1-like agonists SKF 38,393 and YM 435 on platelet-derived growth factor (PDGF) BB-mediated VSMC migration and proliferation were studied. We observed that cells stimulated by PDGF-BB (5 ng/mL), showed increased migration and proliferation. These effects were prevented by coincubation with dopamine, SKF 38,393, or YM 435 (1 to 10 mumol/L), and this prevention was reversed by Sch 23,390 (1 to 10 mumol/l), a specific D1-like antagonist. These actions are mimicked by forskolin (1 to 10 mumol/L), a direct activator of adenylate cyclase and 8-bromo-cAMP at 0.1 to 1 mmol/L and are blocked by a specific protein kinase A inhibitor, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H 89), but not blocked by its negative control, N-[2-(N-formyl)-p-chlorociannamylamino)ethyl]-5-isoquinoline sulfonamide (H 85). PDGF-BB (5 ng/mL)-mediated activation of phospholipase D, protein kinase C, and mitogen activated protein kinase activity were significantly suppressed by coincubation with dopamine. These results suggest that vascular D1-like receptor agonists inhibit migration and proliferation of VSMC, possibly through protein kinase A activation and suppression of activated phospholipase D, protein kinase C, and mitogen-activated protein kinase activity.

Effect of natriuretic peptide family on the oxidized LDL-induced migration of human coronary artery smooth muscle cells.

The migration of medial smooth muscle cells (SMCs) into the intima is proposed to be an important process of intimal thickening in atherosclerotic lesions. The present study examined the possible effect of a novel endothelium-derived relaxing peptide, C-type natriuretic peptide (CNP), on oxidized low-density lipoprotein (LDL)-induced migration of cultured human coronary artery SMCs by the Boyden's chamber method. The effect of CNP was compared with that of atrial and brain natriuretic peptides (ANP and BNP, respectively). Oxidized LDL stimulates SMC migration in a concentration-dependent manner between 20 and 200 micrograms/mL. This stimulation was chemotactic in nature but was not chemokinetic. By contrast, native LDL was without significant activity. CNP-22 clearly inhibited SMC migration stimulated with 200 micrograms/mL oxidized LDL in a concentration-dependent manner between 10(-9) and 10(-6) mol/L. ANP-(1-28) and BNP-32 also inhibited oxidized LDL-induced SMC migration at concentrations of 10(-7) and 10(-6) mol/L, but these effects were weaker than the effect of CNP-22. Such inhibition by these natriuretic peptides was paralleled by an increase in the cellular level of cGMP. Oxidized LDL-induced migration was significantly inhibited by a stable analogue of cGMP, 8-bromo-cGMP, or an activator of the cytosolic guanylate cyclase, sodium nitroprusside. These natriuretic peptides did not suppress the cell adhesion either in the absence or presence of oxidized LDL. These data indicate that oxidized LDL stimulates migration of human coronary artery SMCs and that natriuretic peptides, especially CNP, inhibit this stimulated SMC migration, at least in part, through a cGMP-dependent process. Taken together with the finding that oxidized LDL is present in the intima, CNP may play a role as a local antimigration factor during the process of intimal thickening in hypercholesterolemia-induced coronary atherosclerosis.

Renoprotective effects of a combined endothelin type A/type B receptor antagonist in experimental malignant hypertension.

We previously showed that plasma endothelin-1 (ET-1) concentration was increased in deoxycorticosterone acetate (DOCA)-salt-induced malignant hypertension in spontaneously hypertensive rats (SHR). In contrast, in normal SHR, this value is similar to that seen in Wistar-Kyoto (WKY) rats. The purpose of this study was to examine the effects of the new combined ET type A/type B (ETA/B) receptor antagonist, TAK-044, on the development of hypertension in this model of malignant hypertension. TAK-044 10 mg/kg, which effectively blocks both ETA and ETB receptors, was administered intraperitoneally once per day for 4 weeks in DOCA-salt SHR, and the effects on ET-1 and other parameters were compared with the same values in untreated WKY rats, untreated DOCA-salt SHR, and hydralazine-treated DOCA-salt SHR. DOCA-salt caused marked increases in blood pressure, blood urea nitrogen (BUN), serum creatinine, and plasma ET-1 concentrations in SHR. Both TAK-044 and hydralazine significantly suppressed the increase in blood pressure in DOCA-salt SHR to the same extent. Both treatments also suppressed the increase in BUN and serum creatinine, but this attenuation was less marked with hydralazine than with TAK-044. Neither TAK-044 nor hydralazine affected plasma ET-1 concentration in this model. TAK-044 significantly reduced kidney weight in DOCA-salt SHR, whereas the decrease seen with hydralazine was less marked. Prevention of DOCA-salt-induced renal structural injury (mesangial hypercellularity, glomerular sclerotic changes, and tubulointerstitial damage) in this model was clearly greater with TAK-044 treatment than with hydralazine treatment. These results suggest that endogenous ET-1 may, at least in part, contribute to renal functional and structural damage in malignant DOCA-salt SHR. Our results raise the possibility of renoprotective effects of ETA/B receptor blockers in certain forms of malignant hypertension.

Adrenomedullin is a potent inhibitor of angiotensin II-induced migration of human coronary artery smooth muscle cells.

The migration of coronary artery medial smooth muscle cells (SMCs) into the intima is proposed to be an important process of intimal thickening in coronary atherosclerotic lesions. In the current study, we examined the possible interaction of adrenomedullin, a novel vasorelaxant peptide, and angiotensin II (Ang II) on human coronary artery SMC migration using Boyden's chamber method. Ang II stimulated SMC migration in a concentration-dependent manner between 10(6) and 10(8) mol/L. This stimulation was clearly blocked by the Ang II type 1 receptor antagonist losartan but not by the type 2 receptor antagonist PD 123319. The migration stimulatory effect of Ang II was chemotactic in nature for cultured human coronary artery SMCs but was not chemokinetic. Human adrenomedullin clearly inhibited Ang II-induced migration in a concentration-dependent manner. Human adrenomedullin stimulated cAMP formation in these cells. Inhibition by adrenomedullin of Ang II-induced SMC migration was paralleled by an increase in the cellular level of cAMP. 8-Bromo-cAMP, a cAMP analogue, and forskolin, an activator of adenylate cyclase, inhibited the Ang II-induced SMC migration. These results suggest that Ang II stimulates SMC migration via type 1 receptors in human coronary artery and adrenomedullin inhibits Ang II-induced migration at least partly through a cAMP-dependent mechanism. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, this peptide may play a role as a local antimigration factor in certain pathological conditions.

Natriuretic peptide family as a novel antimigration factor of vascular smooth muscle cells.

Vascular smooth muscle cell (SMC) migration is proposed to be an important process in the initiation and/or progression of atherosclerosis. The present study examined the effects of the natriuretic peptide family (atrial, brain, and C-type natriuretic peptides; ANP, BNP, and CNP) on the migration of cultured rat SMCs, using Boyden's chamber methods. Fetal calf serum (FCS) and platelet-derived growth factor (PDGF)-BB potently stimulated SMC migration. Rat ANP(1-28), rat BNP-45, and rat CNP-22 clearly inhibited SMC migration stimulated with FCS or PDGF-BB in a concentration-dependent manner. CNP-22 had the most potent inhibitory effect compared with other natriuretic peptides. When PDGF-BB-induced migration was separated into chemotactic and chemokinetic activities, the chemotactic component was strongly inhibited by these natriuretic peptides. Such inhibition by these natriuretic peptides was paralleled by an increase in the cellular level of cyclic GMP. The addition of a cyclic GMP analogue, 8-bromo cyclic GMP, and an activator of the cytosolic guanylate cyclase, sodium nitroprusside, significantly inhibited FCS- and PDGF-BB-stimulated migration in a concentration-dependent manner. These results suggest that natriuretic peptides, especially CNP-22, inhibit FCS- or PDGF-BB-stimulated SMC migration at least in part through a cyclic GMP-dependent process. Thus, the natriuretic peptide family may play a role as an antimigration factor of SMCs under certain circumstances.