[A case of multiple and metachronous pleural tuberculomas during the course of anti-tuberculous chemotherapy and follow-up of a caseous pneumonia]

A 21-year-old woman was admitted to our hospital because of high fever, a productive cough and general fatigue. Her chest radiography scan revealed dense consolidation with air-bronchograms in the left lower lobe. Bacterial pneumonia was diagnosed and she was treated with antibiotics, although the specific cause could not be identified. After one month, a bronchoscopy was performed due to lack of improvement of consolidation in chest radiography. A smear examination of the bronchial washing specimen was positive for acid-fast bacilli (AFB) and Mycobacterium tuberculosis (MTB) was confirmed by PCR. After anti-tuberculous drugs (INH, RFP, EB, and PZA) were prescribed for 6 months, chest X-ray findings improved markedly. Two pleural tuberculomas were found in the left upper and lower lung fields 3 months after beginning therapy, and a new pleural tuberculoma appeared in the left upper lung fields 6 months after finishing therapy. Histopathological findings (HE stain) of a CT-guided needle lung biopsy showed epithelioid cell granulomas without caseous necrosis with multinuclear giant cells which were negative for acid-fast bacterium. All of the pleural tuberculomas improved without any additional therapy 18 months after finishing therapy. It was thought that such cases of multiple and metachronous pleural tuberculomas during the course of anti-tuberculous chemotherapy and follow-up of caseous pneumonia are rare. We suggest the possibility that the pleural tuberculomas were due to a paradoxical or hypersensitive reaction to the anti-tuberculous chemotherapy in this case.

[The sequential changes of the serum levels of KL-6, SP-D, and DLCO were followed for a long term in a case of acute bird fancier's lung]

The sequential changes of the serum levels of KL-6, SP-D, and DLco were followed for a long term in a case of acute bird fancier's lung, A 52 years-old-male was admitted to our hospital because of cough, dyspnea on exertion and fever. He has been breeding 12 pigeons in home for the last five years. HRCT of the chest demonstrated diffuse centrilobular nodules and ground-glass opacities with mosaic pattern in bilateral lung fields. Bronchoalveolar lavage (BAL) showed an increased number of lymphocytes with a increased CD4/CD8 ratio, and transbronchial lung biopsy (TBLB) specimen revealed alveolitis with infiltration of lymphoid cells and Masson body in the air spaces. He was diagnosed as having bird fancier's lung because of the elevated antibodies against pigeon dropping extracts (PDE) in the serum and BALF. Respiratory failure continued after complete avoidance of contact with pigeons for a week. Clinical symptoms and chest X-ray findings improved markedly after administration of steroid, and he left the hospital to move into a new house. The serum levels of KL-6 and SP-D were unchanged by antigen avoidance, although those were returning to normal gradually after treatment of steroid. SP-D and KL-6 returned to normal in 8 months and 18 months respectively and DLco was also improved slowly in parallel with a decrease of these markers. These results suggest that the serum KL-6 level and DLco reflect the disease activity showing gradual recovery of alveolitis in such a long period.

[Case of secondary chronic necrotic pulmonary aspergillosis that developed after pneumococcal pneumonia complicated by lung abscess formation]

The patient was a 61-year-old man. From the end of May 2007 he suffered from pain in the left anterior chest, had fever and consulted our hospital on May 27. On admission chest CT revealed consolidation in the left lung. In venous blood and sputum culture Streptococcus pneumoniae was identified as the causative organism, but despite improvement as a result of treatment, the upper lobe of the left lung showed cavity formation. Inside the cavity, fluid level formation was observed and percutaneous cavernous drainage was performed. Pus culture revealed infection with Aspergillus fumigatus, and we diagnosed chronic necrotizing pulmonary aspergillosis (CNPA). In addition to intravenous antifungal drug administration, 20 mg of amphotericin B (AMPH-B) was administered intracavitary. As symptoms and laboratory findings improved, the patient was discharged on October 12. We reported this case because pneumococcal pneumonia complicated by lung abscess formation is relatively rare, and topical treatment was effective against CNPA.

Effect of angiotensin-converting enzyme inhibitor on left ventricular parameters and circulating brain natriuretic peptide in elderly hypertensives with left venticular hypertrophy

In the elderly, left ventricular hypertrophy (LVH) is a powerful risk factor for cardiovascular events and cardiovascular death. The purpose of the present study is to investigate the effect of long-term effective blood pressure control with the angiotensin-converting enzyme (ACE) inhibitor temocapril on left ventricular (LV) mass and function indices and the circulating concentration of the cardiac hormone brain natriuretic peptide (BNP) in elderly hypertensives with LVH. Temocapril treatment was administered for 1 year to 11 elderly hypertensives (mean age, 72 years) with LVH. Cardiac dimensions and circulating concentrations of BNP were monitored before initiation of treatment and after 1 year of treatment. At entry, BNP levels were positively correlated with the LV mass index, but were not correlated with the mean blood pressure, LV ejection fraction, or E/A ratio (the ratio of peak transmitral flow velocity in early diastole, peak E, to that in late diastole, peak A). After 1 year, temocapril treatment resulted in effective control of blood pressure. The treatment did not affect the LV ejection fraction, but modestly increased the E/A ratio. Temocapril significantly reduced septal and posterior wall thickness and the LV mass index. BNP significantly declined after 1 year. Changes in BNP were significantly related to changes in the LV mass index, but were not related to changes in the mean blood pressure, LV ejection fraction, or E/A ratio. The results suggest that long-term ACE inhibitor treatment with temocapril can induce the regression of LV mass and reduce elevated plasma BNP in elderly hypertensive patients with LVH. In this study, changes in BNP reflected the magnitude of regression of LVH.

Dopamine as a Novel Antimigration Factor of Vascular Smooth Muscle Cells Through D 1a and D 1b Dopamine Receptors

P82

Vascular smooth muscle cell (VSMC) migration is believed to play a key role in atherosclerosis. To elucidate the roles of rat vascular D 1A and D 1B dopamine receptors in atherosclerosis, the effect of antisense oligonucleotides (AS) to D 1A (+1-+21 of rat D 1A receptors cDNA) and D 1B (-12-+6 of rat D 1B receptors cDNA) receptors on dopamine-mediated suppression of platelet-derived growth factor (PDGF) BB-mediated VSMC migration evaluated by Boyden′s chamber method was studied. To avoid the degradation, phosphothioate-modified oligodeoxynucleotides were synthesized and purified by high-performance liquid chromatography. These oligonucleotides were added to serum free medium for 24 h before the start of PDGF BB stimulation with transfection using lipofectin reagent. Immunohistochemical studies (double staining) demonstrated the coexistence of D 1A and D 1B dopamine receptors in single VSMC derived from rat renal artery. Western blotting revealed a band of approximately 70 kD for D 1A and D 1B dopamine receptors. Increased VSMC migration by PDGF BB 5 ng/ml (16-fold) was suppressed significantly by coincubation with dopamine 0.025-10 μmol/l (15-59%). This suppression by dopamine 10 μmol/l was reversed by D 1A AS 46% and D 1B AS 51%, but by neither sense (S) nor scramble (RS) oligonucleotides to these receptors. These suppression by antisense oligonucleotides (21-51%) are dose-dependent (1-10 μmol/l) and time-dependent (0-4 hrs). Dopamine 10 μmol/l-induced cyclic AMP formation is also suppressed by D 1A AS 50% and D 1B AS 58%, but by neither S nor RS to these receptors. PDGF BB (5 ng/ml)-mediated activation of phospholipase D (PLD) activity (107%) measured by [ 3 H]-ethanolamine and protein kinase C (PKC) activity (111%) activities measured by synthetic peptide phosphorylation were significantly suppressed by coincubation with dopamine 10 μmol/l (48%, 49%), which was reversed by D 1A AS 45% and D 1B AS 50%, but by neither S nor RS to these receptors. These results suggest that vascular D 1A and D 1B receptors inhibit migration of VSMC, possibly through cAMP formation and suppression of PLD and PKC activity.

Effects of cardiac natriuretic peptides on oxidized low-density lipoprotein- and lysophosphatidylcholine-induced human mesangial cell migration

The objectives of the present study were (1) to determine whether oxidized LDL and lysophosphatidylcholine (lyso-PtdCho), a major phospholipid component of oxidized LDL, stimulate the migration of cultured human mesangial cells and (2) to investigate the possible effects on mesangial cell migration of the cardiac natriuretic peptides atrial and brain natriuretic peptide (ANP and BNP). Oxidized LDL (10 and 100 microg/mL) and lyso-PtdCho (10(-7) to 10(-5) mol/L) stimulated migration in a concentration-dependent manner. In contrast, the effects of native LDL and phosphatidylcholine were modest or nonexistent. Protein kinase C (PKC) inhibitor and downregulation of PKC activity by phorbol ester inhibited oxidized LDL- and lyso-PtdCho-induced migration. Human ANP(1-28) and human BNP-32 significantly inhibited oxidized LDL- and lyso-PtdCho-induced migration in a concentration-dependent manner. C-ANF (des-[Glu(18),Ser(19),Gly(20),Leu(21),Gly(22)]ANP(4-23)), a specific ligand for ANP clearance receptors, could not inhibit oxidized LDL- and lyso-PtdCho-induced migration. Inhibition by ANP and BNP of lyso-PtdCho-induced migration was paralleled by an increase in the cellular level of GMP. Oxidized LDL- and lyso-PtdCho-induced migrations were inhibited by 8-bromo-cGMP. The results suggest that oxidized LDL and lyso-PtdCho stimulate the migration of human mesangial cells, at least in part, through a PKC-dependent process and that ANP and BNP inhibit this stimulated migration, probably through a cGMP-dependent process.

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.

Anti-atherosclerotic action of vascular D1 receptors

1. 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 (D1 and D5) receptors in atherosclerosis, the effects of dopamine and the specific D1-like receptor agonists SKF 38393 and YM 435 on platelet-derived growth factor (PDGF)-BB-mediated VSMC migration, proliferation and hypertrophy were investigated. 2. We observed that cell stimulated by 5 ng/mL PDGF-BB showed increased migration, proliferation and hypertrophy. These effects were prevented by co-incubation with dopamine, SKF 38393 or YM 435 at 1-10 mumol/L and this prevention was reversed by Sch 23390 (1-10 mumol/L), a specific D1-like receptor antagonist. These actions of D1-like receptor agonists were mimicked by 1-10 mumol/L forskolin, a direct activator of adenylate cyclase, and 0.1-1 mmol/L 8-bromo-cAMP. The actions were blocked by the specific protein kinase A (PKA) inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline-sulphonamide (H 89), but were not blocked by its negative control N-[2-(N-formyl-p-chlorocinnamylamino) ethyl]-5-isoquinoline sulphonamide (H 85). Platelet-derived growth factor-BB (5 ng/mL)-mediated activation of phospholipase D (PLD), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity was significantly suppressed by co-incubation with dopamine. 3. These results suggest that vascular D1-like receptor agonists inhibit migration, proliferation and hypertrophy of VSMC, possibly through the activation of PKA and the suppression of activated PLD, PKC and MAPK activity.

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.

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.

Endothelin production in cultured vascular smooth muscle cells--modulation by the atrial, brain, and C-type natriuretic peptide system

We examined the regulatory mechanisms of endothelin-1 (ET-1) production in cultured rat vascular smooth muscle cells (VSMC) with a special focus on the roles of protein kinase C (PKC)- and cyclic guanosine-3',5'-monophosphate (GMP)-mediated signaling systems. Effects of atrial, brain, and C-type natriuretic peptides (ANP, BNP, and CNP) on angiotensin II (Ang II)-, and arginine vasopressin (AVP)-induced production of ET-1 were examined in cultured rat aortic VSMC. Ang II and AVP stimulated ET-1 production in a concentration-dependent manner through angiotensin subtype 1 (AT1) and vasopressin subtype 1 (V1) receptors, respectively. The stimulatory effects of Ang II and AVP were markedly abolished in PKC-depleted cells. Rat ANP (1-28), rat BNP-45, and rat CNP-22 potently inhibited Ang II- and AVP-stimulated ET-1 production in a concentration-dependent manner, respectively. The inhibitory effect by CNP on ET-1 production was paralleled by an increase in the cellular level of cyclic GMR.8-Bromo cyclic GMP reduced the stimulated ET-1 production by Ang II and AVP. These results indicate that Ang II and AVP stimulate ET-1 production in cultured rat VSMC through AT1 and V1 receptors by a mechanism probably involving activation of PKC, and that ANP, BNP, and CNP inhibit this stimulated production through a cyclic GMP-dependent process.

Changes in plasma cardiac natriuretic peptides concentrations during 1 year treatment with angiotensin-converting enzyme inhibitor in elderly hypertensive patients with left ventricular hypertrophy

Plasma concentrations of atrial and brain natriuretic peptides (ANP and BNP) are high in patients with hypertension and congestive heart failure. The present study examined changes in plasma ANP and BNP concentrations during 1 year of monotherapy with enalapril in elderly hypertensive patients with left ventricular (LV) hypertrophy. Eight elderly hypertensive patients with LV hypertrophy were treated with enalapril for 1 year, during which time serial changes were recorded in LV mass index, LV systolic function, and plasma concentrations of ANP and BNP. Enalapril maintained systolic and diastolic blood pressure in the normal range for over 1 year. Treatment significantly reduced posterior wall thickness at 6 months, and more so at 1 year, and tended to reduce septal wall thickness and LV mass index at 1 year. LV ejection fraction was slightly but significantly increased at 1 year. Plasma ANP and BNP, which were markedly elevated at study entry, both decreased after 1 year of enalapril. These results suggest that 1 year of treatment with enalapril caused both a modest regression of LV hypertrophy and a modest improvement in LV systolic function in our selected group of elderly hypertensive patients. The drug reduced elevated plasma ANP and BNP levels but did not alter BUN and serum creatinine levels. Enalapril appears to be useful for the treatment of elderly hypertensive patients with LV hypertrophy.

An accelerated increase of plasma adrenomedullin in acute asthma

A novel vasorelaxant peptide, adrenomedullin (AM), has been isolated from the acid extract of human pheochromocytoma. We have recently shown that AM inhibits histamine- and acetylcholine-induced bronchoconstriction in anesthetized guinea pigs in vivo, and this bronchodilatory effect is long-lasting. Here, we measured plasma AM concentrations in nine patients with an acute attack of bronchial asthma. The results were compared with values in 30 age-matched normal control subjects and seven age-matched stable asthmatic patients. The mean AM concentrations of patients with an acute asthma attack (98 +/- 22 pg/mL) were clearly higher than those of normal control subjects (18 +/- 2 pg/mL) and stable asthmatic patients (21 +/- 3 pg/mL). Reverse-phase high-performance liquid chromatography (HPLC) showed that the major component of plasma immunoreactive AM in patients with an asthma attack and in normal subjects equally corresponded to authentic human AM(1-52). Our results suggest that plasma AM is markedly increased in many of the patients during an acute attack of bronchial asthma, but it is not observed in stable asthmatic patients. Although this report is preliminary, the observed increase of circulating AM during an acute asthma attack may represent a compensatory mechanism against the bronchoconstriction, probably through its bronchodilatory action.

Interaction of adrenomedullin and platelet-derived growth factor on rat mesangial cell production of endothelin

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.

Adrenomedullin as a novel antiproliferative factor of vascular smooth muscle cells

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.

Plasma adrenomedullin concentrations in essential hypertension

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).

Promotion of nitric oxide formation by heparin in cultured aortic endothelial cells from spontaneously hypertensive rats

1. The present study examined the effect of heparin on nitric oxide (NO) formation and cyclic guanosine 3', 5'-monophosphate (cGMP) levels in cultured aortic endothelial cells (EC) from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. 2. Bradykinin (BK), adenosine diphosphate (ADP), Ca2+ ionophore A23187 (Io) and endothelin-3 (ET-3) stimulated the production of NO and cGMP. No significant difference was observed in both NO and cGMP production in EC between WKY and SHR. 3. Heparin enhanced BK-, ADP-, Io- and ET-3-stimulated NO and cGMP production. These enhancements by heparin in EC were significantly greater in SHR than in WKY. 4. Both NO formation and cGMP production stimulated by the agonists and/or heparin were blocked in the presence of NG-monomethyl-L-arginine (LNMMA, 10(-5) mol/L). 5. Increased sulphur level was observed on heparin-treated SHR EC surface compared with that on control SHR EC or on heparin-treated WKY EC surface. 6. These results suggest that heparin promotes agonist-induced NO-cGMP response in cultured EC from SHR.

Promotion of nitric oxide formation by heparin in cultured aortic endothelial cells from spontaneously hypertensive rats

1. The present study examined the effect of heparin on nitric oxide (NO) formation and cyclic guanosine 3', 5'-monophosphate (cGMP) levels in cultured aortic endothelial cells (EC) from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. 2. Bradykinin (BK), adenosine diphosphate (ADP), Ca2+ ionophore A23187 (Io) and endothelin-3 (ET-3) stimulated the production of NO and cGMP. No significant difference was observed in both NO and cGMP production in EC between WKY and SHR. 3. Heparin enhanced BK-, ADP-, Io- and ET-3-stimulated NO and cGMP production. These enhancements by heparin in EC were significantly greater in SHR than in WKY. 4. Both NO formation and cGMP production stimulated by the agonists and/or heparin were blocked in the presence of NG-monomethyl-L-arginine (LNMMA, 10(-5) mol/L). 5. Increased sulphur level was observed on heparin-treated SHR EC surface compared with that on control SHR EC or on heparin-treated WKY EC surface. 6. These results suggest that heparin promotes agonist-induced NO-cGMP response in cultured EC from SHR.

Enhanced phosphoinositide turnover signalling stimulated by endothelin B-type receptor in endothelial cells from spontaneously hypertensive rats

1. Endothelin (ET) B-type (ETB) receptor-mediated signal transduction was examined after stimulation with ET-3 in cultured aortic endothelial cells (EC) from spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats (8 weeks old). 2. The EC from both rat strains expressed only ETB receptor mRNA. The receptor densities and affinities, which were non-selective for ET-1, -2, -3 and Sarafotoxin S6c, and mRNA expression were similar in WKY and SHR. 3. The cytosolic Ca2+ level in the absence of extracellular Ca2+, inositol 1,4,5-trisphosphate levels, protein kinase C and phospholipase C activities in response to ET-3 were greater in SHR EC than in WKY EC. 4. The 45Ca uptake in response to ET-3, which was blocked by Ni2+, was smaller in SHR EC than in WKY EC. 5. The 6-keto-PGF1alpha production was augmented in SHR, though nitric oxide formation after stimulation with ET-3 was similar. 6. These results suggest that ETB receptor-mediated phosphoinositide turnover signalling is augmented in SHR EC through postreceptor mechanism.

Elevated glucose concentration and natriuretic peptides receptor response on vascular smooth muscle of spontaneously hypertensive rats

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 mu mol/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.

Effect of thrombin and PDGF on endothelin production in cultured mesangial cells derived from spontaneously hypertensive rats

1. Basal endothelin-1 (ET-1) production in mesangial cells of spontaneously hypertensive rats (SHR) was not different from that of Wistar-Kyoto (WKY) rats, although a trend toward increased ET-1 production was observed in these cells of SHR. 2. Thrombin and platelet-derived growth factor (PDGF) stimulated ET-1 production in a concentration-dependent manner in these cells of both rat strains, but thrombin- and PDGF-induced stimulation of ET-1 production were clearly greater in cells of SHR than WKY rats. 3. The protein kinase C (PKC)-activating phorbol ester, phorbol myristate acetate, stimulated ET-1 production in cells of both rat strains, but this stimulation was significantly greater in cells of SHR than in cells of WKY rats. 4. An inactive enantiomer of phorbol ester, 4alpha-PDD, had no effect on the ET-1 production in these cells of both rat strains. 5. Neither thrombin nor PDGF stimulated ET-1 production in PKC-depleted cells of both rat strains.