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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.ACE inhibitor therapy was administered for2 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.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 (P0.05) 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 (P0.05) 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 (P0.05).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.

Abstract 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 38393 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 38393, or YM 435 (1 to 10 μmol/L), and this prevention was reversed by Sch 23390 (1 to 10 μmol/l), a specific D1-like antagonist. These actions are mimicked by forskolin (1 to 10 μmol/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.

Abstract 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 μg/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 μg/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.

Abstract 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.

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, specific D1-like agonists SKF 38,393, and YM 435 on platelet-derived growth factor (PDGF) BB-mediated VSMC migration, proliferation, and hypertrophy were studied. We observed that cells stimulated by 5 ng/ml PDGF BB showed increased migration, proliferation and hypertrophy. These effects were prevented by coincubation with dopamine, SKF 38,393, or YM 435 at 1-10 mumol/l, and this prevention was reversed by Sch 23,390 (1-10 mumol/l), a specific D1-like antagonist. These actions are mimicked by 1-10 mumol/l forskolin, a direct activator of adenylate cyclase and 8-bromocyclic AMP at 0.1-1 mmol/l. The actions are blocked by a specific protein kinase A (PKA) inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline-sulfonamide (H 89), but are not blocked by its negative control, N-[2-(N-formyl-p-chlorocinnamylamino) ethyl]-5-isoquinoline sulfonamide (H 85). PDGF-BB (5 ng/ml)-mediated activation of phospholipase D (PLD), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity were significantly suppressed by coincubation with dopamine. These results suggest that vascular D1-like receptor agonists inhibit migration, proliferation and hypertrophy of VSMC, possibly through PKA activation and suppression of activated PLD, PKC and MAPK activity.

Acute hypotension is a major cardiovascular complication of haemodialysis. The cardiac output falls but the total peripheral resistance remains unchanged at the time when hypotension develops. Nitric oxide affects myocardial contraction and noradrenergic response, and regulates vascular tone. This review discusses the mechanisms of acute hypotension occurring during haemodialysis, focusing on the role of nitric oxide in the associated cardiovascular instability.

Abstract Adrenomedullin has recently been isolated from human pheochromocytoma. We designed the present study to examine the effect of adrenomedullin on the production of the vasoconstrictive and growth-promoting peptide endothelin-1 (ET-1) after stimulation with platelet-derived growth factor (PDGF) in cultured rat glomerular mesangial cells. PDGF stimulated ET-1 production in a concentration-dependent manner. Rat adrenomedullin inhibited this stimulated ET-1 production in a concentration-dependent manner between 10 −7 and 10 −8 mol/L. Rat adrenomedullin also increased the cellular level of cAMP in a concentration-dependent manner between 10 −7 and 10 −8 mol/L. Human adrenomedullin was less effective than rat adrenomedullin with respect to inhibiting ET-1 production and increasing cAMP levels. The addition of 8-bromo-cAMP (10 −3 and 10 −4 mol/L) reduced PDGF-induced ET-1 production. Furthermore, forskolin (10 −4 and 10 −5 mol/L), an activator of adenylate cyclase, reduced PDGF-induced ET-1 production. In contrast, the basal production of ET-1 was not significantly altered by rat and human adrenomedullin. These results indicate that adrenomedullin inhibits PDGF-induced ET-1 production in cultured rat mesangial cells, probably through a cAMP-dependent process.

Abstract Adrenomedullin recently has been found to potently stimulate cAMP formation in cultured rat vascular smooth muscle cells (VSMCs). In the present study, we examined the effect of adrenomedullin on the production of a vasoconstrictive and growth-promoting peptide, endothelin-1, after stimulation with a clotting enzyme, thrombin, and a potent mitogen, platelet-derived growth factor (PDGF), in cultured rat VSMCs. Thrombin and PDGF stimulated endothelin-1 production in a dose-dependent manner. Rat adrenomedullin significantly inhibited thrombin- and PDGF-stimulated endothelin-1 production in a dose-dependent manner between 10 −7 and 10 −9 mol/L. Inhibition by rat adrenomedullin of thrombin- and PDGF-stimulated endothelin-1 production was paralleled by an increase in the cellular level of cAMP. Human adrenomedullin also inhibited thrombin- and PDGF-stimulated endothelin-1 production and increased cAMP levels. The addition of 8-bromo-cAMP, a cAMP analogue, reduced thrombin- and PDGF-induced endothelin-1 production. Furthermore, forskolin, a potent activator of adenylate cyclase, reduced thrombin- and PDGF-induced endothelin-1 production. In contrast, basal production of endothelin-1 was not altered by rat or human adrenomedullin. These results indicate that adrenomedullin inhibits not basal but thrombin- and PDGF-induced ET-1 production in cultured VSMCs probably through a cAMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may modulate vascular tone as a paracrine regulator partially through the inhibition of VSMC endothelin-1 production in some pathophysiological states.

Purpose Secretion of brain natriuretic peptide (BNP), a cardiac hormone, is accelerated via hypertrophied ventricles in experimental hypertension. The present study examined whether regression of left ventricular (LV) hypertrophy by long-term treatment with an angiotensin-converting enzyme inhibitor (ACEI) affects plasma BNP concentration in patients with essential hypertension. Patients and methods Thirty-one hypertensive patients with LV hypertrophy were treated with ACEI (16 with enalapril; 15 with lisinopril) for 1 year. Serial changes were recorded in LV mass index, LV systolic function, and plasma concentrations of BNP and atrial natriuretic peptide (ANP). Results ACEI therapy significantly reduced LV mass index at 6 months, and more so at 1 year. Septal and posterior wall thicknesses were also reduced. Plasma BNP and ANP were markedly elevated at study entry, but only BNP levels correlated with LV mass index. Both peptide levels declined after 6 months, and this decline was enhanced at 1 year. There was a close relation between BNP decline and LV mass index reduction overall and with enalapril and lisinopril separately. Changes in ANP and in LV mass index were not related. Conclusion Long-term ACEI therapy can reduce elevated plasma BNP. In this study, changes in BNP reflected the magnitude of regression of LVH. Plasma BNP may be a useful marker for LVH during antihypertensive therapy in patients with essential hypertension and LVH.

Cyclosporine A (CSA) stimulates vascular endothelial cell production of endothelin-1 (ET-1). The present study was designed to test two hypotheses: (1) CSA stimulates ET-1 secretion in cultured rat mesangial cells, and (2) cardiac natriuretic peptides, atrial and brain natriuretic peptides (ANP and BNP), inhibit the above-mentioned secretion in these cells. CSA stimulated ET-1 secretion in a concentration-dependent manner between 10 and 100 ng/mL. In contrast, high concentrations of CSA (10 and 100 micrograms/mL) were cytotoxic and failed to stimulate ET-1 secretion. Rat ANP (1-28) and rat BNP-45 exhibited clearly concentration-related inhibition of CSA-induced ET-1 secretion. This inhibition by ANP and BNP was paralleed by an increase in the cellular level of cyclic guanosine-3',5'-monophosphate (cGMP). Rat ANP (5-25) was less effective than rat ANP (1-28) with respect to inhibiting ET-1 secretion and increasing cellular cGMP. Addition of a cGMP analog, 8-bromo-cGMP, reduced CSA-induced ET-1 secretion. On the other hand, addition of a cyclic adenosine-3',5'-monophosphate (cAMP) analog, 8-bromo-cAMP, did not affect CSA-induced ET-1 secretion. These findings suggest that CSA in low concentrations stimulates ET-1 production in cultured rat mesangial cells, and that cardiac natriuretic peptides inhibit this stimulated production, probably through a cGMP-dependent process.

We showed that two isoforms of platelet-derived growth factor (PDGF), AB and BB, stimulate the secretion of endothelin (ET)-1 from cultured rat mesangial cells. Then, we examined whether PDGF AB and BB stimulate mesangial cell proliferation through the modulation of the endogenous production of ET-1 in these cells. Mitogenesis experiments were assessed by tritiated thymidine incorporation into DNA under highest concentrations (10 ng/ml) of PDGF AB and BB in the presence and absence of anti-ET-1 antiserum or a selective A-type endothelin receptor (ETA receptor) antagonist, BQ-123. PDGF AB and BB potently stimulate thymidine incorporation. This stimulation was significantly attenuated in the presence of either anti-ET-1 antiserum or BQ-123 (10(-7)-10(-5)M). Results suggest that PDGF AB and BB stimulate ET-1 secretion in rat mesangial cells through PDGF beta-receptors, and endogenously produced ET-1 serves to modulate the mitogenic effect of PDGF AB and BB, probably via ETA receptors in these cells.

Heparin inhibits endothelin-1 production in cultured rat mesangial cells. The present study was designed to examine whether heparin inhibits basal or stimulated endothelin-1 production by arginine vasopressin (AVP) and platelet-derived growth factor (PDGF) in cultured rat mesangial cells. In addition, the reversibility of the heparin effect on mesangial cell endothelin-1 production was examined. AVP and PDGF stimulated endothelin-1 secretion in a concentration-dependent manner in these cells. Heparin (10 to 100 U/ml) exhibited concentration-related inhibition of AVP- and PDGF-stimulated endothelin-1 secretion. Heparin also had weak but significant inhibitory effects on basal endothelin-1 secretion in these cells. The protein kinase (PKC)-activating phorbor ester, phorbor myristate acetate (PMA), stimulated endothelin-1 secretion and heparin inhibited PMA-stimulated endothelin-1 secretion. In addition, the inhibitory effect of heparin was completely abolished in PKC-depleted mesangial cells. Mesangial cells which were exposed to a high concentration (100 U/ml) of heparin for 24 hours were capable of producing endothelin-1 after a short lag period of removal of heparin from the culture medium. These mesangial cells also showed recovery of responses to AVP and PDGF by secreting a significantly greater amount of endothelin-1 than the non-stimulated level. These results indicate that heparin potently inhibits mesangial cell endothelin-1 production, especially when stimulated by AVP or PDGF. This inhibitory effect of heparin is probably PKC dependent, and reversible.

Heparin shows blood pressure lowering effect in hypertensive patients and animal models. The present study examined the effect of heparin on vasoconstrictor endothelin-1 (ET-1) production in cultured human umbilical vein endothelial cells (ECs) to elucidate the mechanism of antihypertensive effect of heparin. Heparin suppressed both basal and thrombin-stimulated ET-1 mRNA expression paralleled with a decrease in ET-1 peptide release in a dose-dependent manner. Heparin concomitantly enhanced nitric oxide (NO) formation measured by NO2/NO3 levels and cGMP production in ECs. These enhancements were more marked when ECs were stimulated by thrombin. However, these heparin's effects were blunted in the presence of endothelium-derived nitric oxide (EDNO) synthesizing inhibitor NG-monomethyl L-arginine. Therefore, these results suggest that suppression of ET-1 production by heparin is EDNO mediated.

To examine the role of brain natriuretic peptide (BNP) in acute myocardial infarction (AMI), we measured the plasma concentration of immunoreactive (ir) BNP together with that of atrial natriuretic peptide (ANP) over the 4-week course of AMI in 16 patients treated with early coronary angioplasty. Both the plasma ir-ANP and ir-BNP levels were increased on the first day of the infarction compared with the values in normal subjects. During the clinical course of the infarction, the plasma ir-ANP concentration soon decreased, while the plasma ir-BNP level remained elevated at 2 weeks after the infarction, also exhibiting a high level at 4 weeks. Plasma ir-BNP levels on day 1 or days 14 and 28 were inversely correlated with left ventricular ejection fraction obtained by left ventriculography at the acute or chronic phase, respectively. Plasma ir-BNP concentrations on days 14 and 28 were positively correlated with the maximal myosin light chain I level, an indicator of infarct size. These observations suggest that the plasma ir-BNP level increased to compensate for the ventricular dysfunction associated with the size of the infarct in AMI. BNP may act as a cardiac hormone in AMI, differing somewhat from ANP in its synthetic, secretory, or clearance behavior.

To examine the effects of lipoproteins on the secretion of endothelin-1 from endothelial cells, we measured immunoreactive (ir) endothelin-1 release from cultured human umbilical vein endothelial cells in the presence or absence of various concentrations of native low density lipoprotein (LDL), oxidized LDL, and very low density lipoprotein (VLDL). Cultured endothelial cells secreted ir-endothelin-1 into serum-free medium in a time-dependent manner, and the secretion was clearly stimulated following a 15-24-h incubation with 10 micrograms/ml oxidized LDL. The secretion of ir-endothelin-1 increased in a dose-dependent manner after a 24-h incubation with oxidized LDL, while only a high dose of native LDL and VLDL significantly increased ir-endothelin-1 secretion. The release of ir-endothelin-1 stimulated by 20 micrograms/ml oxidized LDL was reproduced by the same concentration of acetylated LDL but not native LDL. These observations indicate that the release of ir-endothelin-1 from endothelial cells is stimulated by lipoproteins, in particular by oxidized LDL, probably through the endothelial scavenger receptor. This increase in ir-endothelin-1 release induced by oxidized LDL may contribute to the development of atherosclerotic vascular lesions.

The present study examined the effects of atrial, brain, and C-type natriuretic peptides (ANP, BNP, and CNP, respectively) on endothelin-1 (ET-1) secretion after stimulation with arginine vasopressin (AVP), using cultured rat glomerular mesangial cells. AVP stimulated immunoreactive (ir) ET-1 secretion in a concentration-dependent manner via a receptor-mediated process. Rat ANP-(1-28) and rat BNP-45 potently inhibited this stimulated secretion in a concentration-dependent manner. Inhibition by ANP and BNP of AVP-stimulated ET-1 secretion was paralleled by an increase in the medium level of guanosine 3',5'-cyclic monophosphate (cGMP). The addition of a cGMP analogue, 8-bromo-cGMP, reduced the stimulated ET-1 secretion. CNP was much less effective than rat ANP-(1-28) or rat BNP-45 with respect to inhibiting irET-1 secretion and increasing cGMP levels. High-performance liquid chromatography indicated that the major component of irET-1 in the culture medium corresponds to ET-1-(1-21). These findings indicate that AVP stimulates ET-1 secretion in cultured rat mesangial cells and that rat ANP and BNP inhibit this stimulated secretion, probably through a cGMP-dependent process.

In this paper, we present Zuzie2, a computer application designed to help people extend their interpretation of the meaning of their activities, and propose that Zuzie2 is effective in cultivating the power of understanding and expression. In an earlier paper we presented the Constructive Scrapbook computer application which has the potential to make the user analyze expressions, extract significances to consider them deeply, and then create new expressions [1]. Zuzie2 is an improved version of the Constructive Scrapbook. Using this tool, in the same way as with the earlier version, the user arranges compositions of pictures in a two-dimensional space, makes various compositions, and switches them freely. In Zuzie2, we have added a new function that enables users to import composition grounds that show the viewpoints of other users into their works. Our objective is to have children and ordinary people use various facets to analyze their activities and then create new expressions. Humans think and express something in a conceptual framework such as ordering, classification, or quantity. However, the thoughts of a single person have limitations due to the fixed frame of viewpoint. We have designed this tool so that the viewpoints of other persons combine with the user’s work to form new expressive works. We held a workshop using the Zuzie2 application. The results show that this tool has the potential to make users analyze their activities, import other viewpoints to consider them deeply, and then create new expressions.

We examined the inhibitory effect of porcine C-type natriuretic peptide (CNP) on endothelin-1 secretion stimulated by thrombin and angiotensin II (Ang II) in cultured porcine endothelial cells. The results were compared with the effects of atrial (ANP) and brain (BNP) natriuretic peptides. Thrombin and Ang II produced a concentration-dependent stimulation of immunoreactive endothelin-1 secretion, and porcine CNP-22 potently inhibited this stimulated secretion in a concentration-dependent manner. CNP-22 had a stronger inhibitory effect than either porcine ANP(1-28) or porcine BNP-26. In addition, CNP potently increased the cellular level of cyclic guanosine 3',5'-monophosphate (GMP), with the inhibition of immunoreactive endothelin-1 secretion in response to thrombin and Ang II being paralleled by the increase in the cyclic GMP level. The increase of cyclic GMP produced by CNP was also greater than that due to porcine ANP(1-28) or porcine BNP-26. The immunoreactive endothelin-1 in the culture medium had two components on high-performance liquid chromatography; the major one corresponded to endothelin-1 (1-21) and the minor one to big endothelin-1 (porcine 1-39). Treatment with CNP did not affect this profile. Our results suggest that CNP probably inhibits the endothelin-1 secretion stimulated by thrombin and Ang II through a cyclic GMP-dependent process. The increase of cyclic GMP levels and the inhibition of immunoreactive endothelin-1 secretion produced by CNP appear to be greater than those produced by ANP or BNP.

We have recently shown that the porcine aorta releases immunoreactive endothelin-1 in a time-dependent way. Here, we examined the inhibition by atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) of endothelin-1 secretion after stimulation with angiotensin II (Ang II) by using porcine aorta. Ang II dose-dependently stimulated immunoreactive endothelin-1 secretion. Porcine ANP-(1-28) and porcine BNP-26 both inhibited such secretion in a dose-dependent way. The addition of a cyclic guanosine 5'-monophosphate (cGMP) analogue, 8-bromo-cGMP, reduced the immunoreactive endothelin-1 secretion after stimulation with Ang II. In cultured porcine endothelial cells the inhibition by porcine ANP-(1-28) and porcine BNP-26 of immunoreactive endothelin-1 secretion after stimulation with Ang II was paralleled by an increase in the cellular cGMP level. Rat ANP-(5-25) was weaker than porcine ANP-(1-28) in inhibiting immunoreactive endothelin-1 secretion and increasing cGMP in cultured cells. There was negative correlation between the percent decrease in immunoreactive endothelin-1 and the percent increase in cGMP. Neither porcine ANP-(1-28) nor BNP-26 affected the number or sensitivity of Ang II binding sites in cultured porcine endothelial cells. These results suggest that ANP and BNP inhibit endothelin-1 secretion after stimulation with Ang II, probably through a cGMP-dependent process.

In this paper, we present how to use the Constructive Scrapbook to integrate expression and analysis and propose that its design is effective for learning. Constructive Scrapbook is a computer application in which the user arranges compositions of pictures in a two-dimensional space, makes various compositions, and switches them freely. Although subjective expression and objective analysis are treated as different activities in the educational world today, we have designed a tool that handles both types of activities simultaneously through constructive learning. Our objective is to have children and ordinary persons use various facets to analyze their expressions and then create new expressions.We held a workshop using the Constructive Scrapbook. The results show that the tool has the potential to make the user analyze expressions, extract significances to consider them deeply, and then create new expressions.

Recently, we have reported two cases with endothelin (ET)-secreting tumor presenting with hypertension and elevated plasma endothelin-1 (ET-1) levels. The present study examines the histopathology of the ET-secreting tumor in one of these cases. The neoplasm was located in the skin and microscopically characterized as a malignant hemangioendothelioma by remarkable intravascular proliferations of atypical endothelium with the expression of Factor VIII-related antigen in the tumor cells. The tumor enlarged rapidly with rising ET-1 and blood pressure levels. The ET-1 content and its messenger RNA expression in the tumor extract were higher than those from normal parts of skin. ET-1 may play a pathophysiological role in patients with ET-secreting malignant hemangioendothelioma.

The effect of glucocorticoids on the atrial natriuretic factor (ANF)-mediated formation of cyclic guanosine monophosphate (cGMP) by intact vascular smooth muscle cells (VSMC) was studied in rats. Cultured VSMC were obtained from the renal arteries of 14-week-old Wistar rats by the explant method. Micromolar concentrations of dexamethasone, given as pretreatment for 48 hours, suppressed the ANF-mediated response. The dexamethasone-induced suppression was detectable at 6 hours and reached a maximum 24 hours after administration in a dose-dependent manner. Inhibitors of protein synthesis blocked this effect of the glucocorticoid. The basal activity of guanylate cyclase in the dexamethasone-treated cells was lower than in the control cells. Other steroids having glucocorticoid action mimicked this suppression of the ANF-mediated response. This suppression was blocked by a glucocorticoid receptor antagonist. The results suggest that glucocorticoids suppress ANF-mediated cGMP formation by VSMC through glucocorticoid type II receptors and the induction of protein synthesis. Suppression of the ANF-mediated response may play a role in glucocorticoid-induced hypertension.

Endothelin plays a role in the regulation of vascular tonus. Therefore, it has been hypothesized that increased production or release of endothelin or both may contribute to the pathogenesis of hypertension. To assess any changes in the plasma endothelin concentration in essential hypertension, plasma immunoreactive endothelin concentrations were measured in patients with essential hypertension.We measured plasma immunoreactive endothelin concentrations in 42 subjects with essential hypertension, 12 subjects with borderline hypertension, and 25 normotensive control subjects.The concentrations were higher in hypertensive patients than in borderline hypertensive patients and normotensive subjects (both p less than 0.05), although values in normotensives and hypertensives overlapped. Reverse-phase high-performance liquid chromatography (HPLC) and radioimmuno-assay showed two components of plasma endothelin, one corresponding to synthetic endothelin-1 (1-21) and the other corresponding to synthetic big endothelin (human, 1-38). The HPLC profile of plasma endothelin of hypertensive patients was the same as that of normotensive subjects. Hypertensives with reduced glomerular filtration rates or increased serum creatinine levels had higher plasma endothelin concentrations than hypertensive patients as a whole (p less than 0.05). Mean blood pressure and serum creatinine levels were correlated to plasma endothelin in the hypertensives. Correlation was negative between glomerular filtration rate and the endothelin level in the hypertensives.Plasma endothelin was elevated in many hypertensive patients with severe hypertension or renal involvement. Its major components were endothelin-1 and big endothelin.

The present study was designed to examine the effect of antihypertensive therapy on plasma and atrial concentration of atrial natriuretic peptides (ANP) in spontaneously hypertensive rats (SHR) by using alpha-methyldopa and hydralazine. Methyldopa and hydralazine treatment reduced blood pressure (P less than .05, P less than .05, respectively); however, ventricular weight was reduced by methyldopa (P less than .05) but not by hydralazine. Plasma ANP concentration in untreated SHR was higher than that observed in Wistar-Kyoto rats (WKY). Methyldopa treatment decreased plasma ANP concentration, but hydralazine treatment did not. Moreover, plasma ANP concentration and ventricular weight were positively correlated in untreated and treated SHR. The left atrial ANP concentration in untreated SHR was lower than that observed in WKY. Methyldopa treatment increased left atrial ANP concentration, but hydralazine treatment did not. These results suggest that the ANP release from the left atrium is chronically stimulated in adult SHR, and that a decrease in plasma ANP concentration by methyldopa treatment is, in part, associated with the decline of ANP release from the heart due to the reductions of blood pressure and cardiac hypertrophy.

The acute effects of endothelin, a potent vasoconstrictor peptide, were investigated on renal hemodynamics, blood pressure and heart rate in conscious and unrestrained DOCA-salt hypertensive rats to compare with those in normotensive, sham-operated rats. The plasma concentration of immunoreactive endothelin was measured following the administration of endothelin, 0.4 nmole IV. After a dose of 1 nmole/kg IV, the blood pressure fell transiently and then rose gradually, while the renal blood flow remained decreased throughout the observation period. Both the blood pressure elevation and the renal blood flow decline in DOCA-salt hypertensive rats exceeded that in controls. In both experimental groups the arterial plasma endothelin concentration decreased rapidly after the peak was achieved. The disappearance of endothelin from plasma was significantly delayed in the DOCA-salt hypertensive rats. These findings suggest that the marked increase in blood pressure and the altered renal hemodynamics induced by endothelin in DOCA-salt hypertensive rats are due in part to a decrease in endothelin clearance.

Summary 1. Hyperglycaemia is believed to be a major cause of diabetic vascular complications such as accelerated atherosclerosis. In order to elucidate the effect of hyperglycaemia on vascular response in spontaneously hypertensive rats (SHR), the natriuretic peptides receptor responses to vascular smooth muscle cells (VSMC) which are thought to suppress atherosclerosis were studied under high glucose (HG:22.2 mmol/L) conditions. 2. The total number of cells in SHR is higher and natriuretic peptides receptor response is smaller than that of cells in the Wistar-Kyoto (WKY) rat. Membrane bound protein kinase C (PKC) activity in HG or SHR is higher compared to that of cells in normal glucose (NG:5.6 mmol/L) or WKY. Cells cultured in HG for at least 2 passages had higher total cell number and receptor mediated cGMP formation were suppressed compared to cells cultured in NG both in SHR and WKY. Specific PKC inhibitor PKC (19–36) 1 μmol/L prevented HG induced suppression of natriuretic peptides response. 3. These results show that hyperglycaemia may be linked to suppressed natriuretic peptides receptor response which is caused by increased PKC activity both in WKY and SHR. This suppressed response may cause the accelerated atherosclerosis by hyperglycaemia.

Heparin shows a blood pressure-lowering effect in various hypertensive rat models. This study was designed to examine the effect of heparin on vasoconstrictor endothelin-1 (ET-1) production by cultured human umbilical vein endothelial cells (HUVECs). ET-1 and cyclic GMP levels in the medium were determined by radioimmunoassay. ET-1 mRNA was quantified by densitometric Northern blot analysis. ET-1 was released into the medium in a time-dependent manner, and its release was augmented by thrombin (10 U/ml). Heparin suppressed both basal and thrombin-stimulated ET-1 secretion and its mRNA expression in a dose-dependent manner. Heparin suppressed ET-1 mRNA expression in a time-dependent fashion. Heparin did not suppress both basal and thrombin-stimulated ET-1 production in the presence of NG-monomethyl-L-arginine (L-NMMA) (10(-5) M). The production of cGMP stimulated by thrombin was significantly enhanced by heparin, but not in the presence of L-NMMA (10(-5) M). Heparin may suppress vasoconstrictor ET-1 production mediated by the enhancement of endothelium-derived nitric oxide in HUVECs.

Brain natriuretic peptide (BNP) is secreted through the coronary sinus of the human heart. The purpose of this study was to determine whether BNP secretion from the heart is stimulated by exercise and to examine the relationship between pulmonary arterial BNP concentrations and hemodynamic measurements, especially cardiopulmonary hemodynamics, during exercise in patients with essential hypertension. The exercise protocol consisted of three fixed workloads (25, 50, 75 W) on a bicycle ergometer in the supine position. The mean pulmonary arterial BNP level at rest was 14.8 +/- 4.1 pg/mL, and BNP values gradually increased with higher stages of exercise. At the maximum exercise stage, the BNP value increased to 40.9 +/- 6.5 pg/mL. Close correlations of pulmonary arterial pressure (PAP) and pulmonary arterial wedge pressure (PAWP) with pulmonary arterial BNP level were observed at four points at rest and during each stage of exercise. In contrast, heart rate, mean blood pressure, cardiac index (CI), and stroke index (SI) were not correlated with BNP values. Results suggest that cardiac secretion of BNP was increased during exercise in essential hypertensive subjects, and the observed increase of BNP may be related to elevated PAP and PAWP. The enhancement of BNP secretion during exercise in these patients may reflect increased redistribution of blood to the cardiopulmonary compartment.

The present study was designed to examine the possible influence of hypoxia on plasma immunoreactive (ir) endothelin-1 concentrations in anesthetized rats. Plasma ir-endothelin-1 concentration, blood pressure, heart rate, and arterial gas levels were measured 1 and 2 hours after exposure to normoxic (20% O2), mildly hypoxic (16% O2), and severely hypoxic (12% O2) gas. Mean blood pressure and heart rate were significantly decreased and the plasma ir-endothelin-1 concentration was significantly increased in severely hypoxic rats after both 1 and 2 hours. In mildly hypoxic rats, the plasma ir-endothelin-1 concentration was also increased, but this value was not statistically significant. The plasma ir-endothelin-1 concentration was inversely correlated with arterial blood PO2 in the three study groups (normoxic, mildly hypoxic, and severely hypoxic rats) after 1 hour (n = 18, r = -.74, P less than .01), and after 2 hours (n = 18, r = .71, P less than .01). Our results indicate that severe hypoxia increased the plasma ir-endothelin-1 level in anesthetized rats. The observed increase in plasma ir-endothelin-1 level may represent a compensatory mechanism against the blood pressure reduction associated with severe hypoxia.

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.

Background —To explore the role of intracellular oxidative stress in high glucose–induced atherogenesis, we examined the effect of probucol and/or α-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, [ 3 H]thymidine incorporation, and cell number compared with VSMCs treated with normal-glucose medium (5.6 mmol/L+16.6 mmol/L mannose). Probucol and α-tocopherol significantly suppressed high glucose–induced increase in VSMC migration, cell number, and [ 3 H]thymidine incorporation. Probucol and α-tocopherol suppressed high glucose–induced elevation of the cytosolic ratio of NADH/NAD + , phospholipase D, and membrane-bound protein kinase C activation. Probucol, α-tocopherol, and calphostin C improved the high glucose–induced suppression of insulin-mediated [ 3 H]deoxyglucose uptake. Chronic high-glucose treatment increased the oxidative stress, which was significantly suppressed by probucol, α-tocopherol, suramin, and calphostin C. Conclusions —These findings suggest that probucol and α-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.

The present study was designed to examine the effect of synthetic rat endothelin, a novel potent vasoconstrictor isolated from endothelial cells, on the release of immunoreactive atrial natriuretic factor (ir-ANF) in anesthetized rats. Systemic blood pressure and plasma ir-ANF concentration were measured at 1, 3, 5, 15, 30, and 60 minutes after rat endothelin administration (0.01, 0.10, 1.00 nmol/kg body weight [BW]). Administration of rat endothelin caused a long-lasting increase in mean blood pressure and produced a dose-dependent increase in plasma ir-ANF that peaked 5 minutes after the injection and remained higher than the basal value 60 minutes after the injection. These data suggest that administration of pharmacological doses of rat endothelin produces a profound release of ir-ANF into the circulation, which may cause vasodilation and diuresis to antagonize the effect of endothelin.

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 hepari is reversible and not simply a function of killing cells.

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-1 (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 5×10 −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 5×10 −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-β 1 . 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.

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 μmol/L) stimulated ET-1 mRNA expression in a dose-dependent manner. A nitric oxide synthesis inhibitor, N G -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.

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 Ca 2+ 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 Ca 2+ elevation.

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 ET A 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 ET A 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.

Abstract 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%, [ 3 H]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. Troglitazone at 100 nmol/L and 1 μmol/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 [ 3 H]thymidine incorporation by 45% and 60% (n=6, P 3 H]deoxyglucose uptake was blocked by a protein kinase C (PKC) inhibitor (calphostin C, 1 μmol/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 [ 3 H]thymidine incorporation was suppressed by troglitazone. Troglitazone (1 μmol/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 μmol/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.

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.

Abstract 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.

Erythrocyte deformation is an important regulatory factor of the microcirculation. The present study was designed to examine whether erythrocyte deformability is altered in hypercholesterolemic patients and, if so, whether cholesterol-lowering therapy affects this parameter in these patients. The erythrocyte deformability of 37 hypercholesterolemic patients was evaluated before and after 1 year of therapy with pravastatin, an inhibitor of hepatic hydroxymethyl glutaryl coenzyme A reductase, under various shear stresses (4.7, 9.5, 23.6, 47.3, 118.1, and 236.2 dyne/cm2) using laser diffractometry. At study entry, erythrocyte deformability under 4.7 and 9.5 dyne/cm2 shear stress, which is actually observed in human vessels, was reduced compared with that in 20 age-matched normocholesterolemic subjects and was inversely correlated with serum cholesterol and low-density lipoprotein (LDL) cholesterol. Pravastatin therapy for 1 year, which reduced serum cholesterol from 288 ± 28 to 223 ± 20 mg/dL, significantly improved erythrocyte deformability by approximately 20%. There was a significant relation between the improvement of erythrocyte deformability and the reduction of serum cholesterol or LDL cholesterol. The results suggest that erythrocyte deformability is reduced in hypercholesterolemic patients, and that long-term cholesterol-lowering therapy can improve reduced erythrocyte deformability, which may contribute to the improvement of organ perfusion.

Vascular smooth muscle cell (VSMC) hypertrophy is believed to play some roles in atherosclerosis. To elucidate the role of vascular D1-like receptors in VSMC hypertrophy, the effects of dopamine and specific D1-like receptor agonist SKF 38393 and YM 435 on platelet-derived growth factor (PDGF) BB-mediated VSMC hypertrophy was studied. We observed that cells stimulated by PDGF-BB 5 ng/mL showed increased VSMC hypertrophy. These effects were prevented by coincubation with dopamine, SKF 38393, and YM 435 1-10 μmol/L, and this prevention was reversed by Sch 23390 1 to 10 μmol/L, a specific D1-like receptor antagonist. These actions are mimicked by forskolin 1 to 10 μmol/L, a direct activator of adenylate cyclase and 8-bromo-cAMP 0.1 to 1 mmol/L, and are blocked by a specific protein kinase A (PKA) inhibitor N -[2-(P-bromocinnamylamino)ethyl]-5-isoquinoline-sulfonamide (H 89) but not blocked by its negative control. PDGF-BB (5 ng/mL)-mediated mitogen-activated protein kinase (MAPK) activity was significantly suppressed by coincubation with D1-like receptor agonists, which were reversed by PKA inhibitor H 89. These results suggest that vascular D1-like receptor agonists inhibit hypertrophy of VSMC, possibly through PKA activation and suppression of activated MAPK activity.

OBJECTIVE The present study was designed to examine whether adrenomedullin affects fetal calf serum (FCS)-stimulated proliferation in cultured rat vascular smooth muscle cells (VSMCs). METHODS Rat VSMCs were grown from explants of Sprague-Dawley rat aorta and were grown using the standard cell culture method. After incubation for 24 h with various concentrations of adrenomedullin in the presence of 5% FCS, trichloroacetic acid-insoluble tritiated thymidine was measured in a liquid scintillation counter. After incubation for 48 h, cell counts were performed. Cyclic adenosine 3',5'-monophosphate (AMP) levels were determined by radioimmunoassay. RESULTS Rat adrenomedullin exhibited concentration-dependent inhibition of the FCS-stimulated increase in thymidine incorporation between 10(-7) and 10(-9) mol/l and of cell number at 10(-7) mol/l. However, the calcitonin generelated peptide (CGRP) receptor antagonist human CGRP(8-37) abolished these antiproliferative effects of rat adrenomedullin. Inhibition by adrenomedullin of FCS-stimulated cellular proliferation was paralleled by an increase in the cellular level of cyclic AMP. 8-Bromocyclic AMP, a cyclic AMP analogue, and forskolin, an activator of adenylate cyclase, inhibited the FCS-stimulated increase in thymidine incorporation and cell number. CONCLUSIONS These results suggest that adrenomedullin inhibits FCS-stimulated proliferation in cultured rat VSMCs, probably through a cyclic AMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may play a role as an antiproliferative factor for VSMCs in a paracrine fashion.

Abstract We designed the present study to assess any changes in plasma concentrations of the novel vasorelaxant peptide adrenomedullin in patients with essential hypertension. Plasma adrenomedullin concentrations were measured in 45 patients with untreated essential hypertension, 15 patients with borderline hypertension, and 30 normotensive control subjects. After 4 weeks of effective calcium channel blocker–based antihypertensive therapy, adrenomedullin concentrations were measured again. The concentrations were higher in hypertensive patients with increased serum creatinine levels or decreased glomerular filtration rates compared with borderline hypertensive patients and normotensive subjects, although values in normotensive and hypertensive individuals overlapped. Plasma adrenomedullin concentrations were positively correlated with serum creatinine levels and inversely correlated with glomerular filtration rates in the hypertensive patients, whereas adrenomedullin values were not correlated with blood pressure level, left ventricular mass index, or left ventricular ejection fraction. Despite blood pressure control with antihypertensive therapy, plasma adrenomedullin concentrations were not changed. Reversed-phase high-performance liquid chromatographic analysis showed that a major component of immunoreactive adrenomedullin in the plasma of normotensive subjects and hypertensive patients is human adrenomedullin-(1-52). These results indicate that plasma adrenomedullin concentrations are elevated in many hypertensive patients with renal dysfunction and its major component is human adrenomedullin-(1-52).

Abstract Vascular remodeling is a key process in the pathophysiology of atherosclerosis. Recent evidence suggests that high glucose levels may function as a vascular smooth muscle growth and proliferation–promoting substance. To explore the role of the polyol pathway in this process, we examined the effect of an aldose reductase inhibitor (ARI), epalrestat, on the growth characteristics of cultured rat vascular smooth muscle cells (VSMCs). Epalrestat (10 nmol/L, 1 μmol/L) significantly suppressed the high glucose–induced proliferative effect as measured by [ 3 H]thymidine incorporation by 67% and 82% in cell number, suggesting ARI as an antimitogenic factor. In VSMCs, epalrestat (10 nmol/L, 1 μmol/L) significantly suppressed the high glucose–induced incorporation of [ 3 H]leucine by 45% and 58% with the concomitant reduction of the cell size estimated by flowcytometry. Epalrestat (1 μmol/L) also suppressed high glucose–induced intracellular NADH/NAD + increase and membrane-bound protein kinase C activation. These results indicate that this ARI possesses an antiproliferative and antihypertrophic action on VSMCs induced by high glucose possibly through protein kinase C suppression.