HLA and atopic dermatitis with high serum IgE levels

Patients with atopic dermatitis usually exhibit allergen-specific IgE antibodies against several environmental antigens. HLA restriction is presumed to be involved in the recognition of such antigens, but several previous reports have so far failed to find a significant association between atopic dermatitis and HLA antigens. In this study we examined 38 unrelated Japanese patients with severe atopic dermatitis and high serum IgE levels (greater than 800 U/ml). We investigated the serological HLA types and HLA class II alleles in this group of patients with atopic dermatitis. Frequencies of HLA-A24, A33, Cwblank, B44, DR13 and HLA-DRB1*1302, DQB1*0604, DPB1*0301 alleles were increased in the patients. In contrast, frequencies of HLA-Cw1, Bw6, DR4, DR53, and HLA-DQB1*0302 allele were decreased. However, none of these remained significant after p values were corrected. Further study on HLA association with atopic dermatitis through characterization of specific antigens or antigen epitopes is needed.

Phosphoinositide turnover signaling stimulated by ET-3 in endothelial cells from spontaneously hypertensive rats

Endothelin (ET) B-type receptor-mediated signal transduction after stimulation with ET-3 was examined in cultured aortic endothelial cells obtained from spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. The purpose of this study was to elucidate ETB receptor-mediated response in endothelial cells from hypertensive rat models. Non-isopeptide-selective displacement and affinity in these binding experiments suggest that aortic endothelial cell receptors for ET-3 correspond to ETB receptor subtypes. These receptors for ET-3 were similar in WKY and SHR endothelial cells. ETB receptor mRNA expression in cultured endothelial cells was also similar in WKY and SHR. However, the cytosolic free Ca2+ level in the absence of extracellular Ca2+ as well as the inositol 1,4,5-trisphosphate level in response to ET-3 were greater in endothelial cells from SHR than in those from WKY. Phospholipase C and protein kinase C activities after stimulation with ET-3 were also greater in SHR than in WKY. The 6-ketoprostaglandin F1 alpha production was also augmented in SHR, although nitric oxide formation and guanosine 3',5'-cyclic monophosphate production after stimulation with ET-3 were similar in WKY and SHR. We conclude that the phosphoinositide turnover signaling stimulated by ET-3 is augmented in cultured aortic endothelial cells from SHR compared with those from WKY.

Involvement of enzymatic degradation in the inactivation of tachykinin neurotransmitters in neonatal rat spinal cord

1. The possible involvement of enzymatic degradation in the inactivation of tachykinin neurotransmitters was examined in the spinal cord of the neonatal rat. 2. The magnitude of substance P (SP)- or neurokinin A (NKA)-evoked depolarization of a lumbar ventral root in the isolated spinal cord preparation was increased by a mixture of peptidase inhibitors, consisting of actinonin (6 microM), arphamenine B (6 microM), bestatin (10 microM), captopril (10 microM) and thiorphan (0.3 microM). The mixture augmented the response to NKA more markedly than that to SP. 3. In the isolated spinal cord-cutaneous nerve preparation, the saphenous nerve-evoked slow depolarization of the L3 ventral root was augmented by the mixture of peptidase inhibitors in the presence of naloxone (0.5 microM) but not in the presence of both naloxone and a tachykinin receptor antagonist, GR71251 (5 microM). 4. Application of capsaicin (0.5 microM) for 6 min to the spinal cord evoked an increase in the release of SP from the spinal cord. The amount of SP released was significantly augmented by the mixture of peptidase inhibitors. 5. Synaptic membrane fractions were prepared from neonatal rat spinal cords. These fractions showed degrading activities for SP and NKA and the activities were inhibited by the mixture of peptidase inhibitors. The degrading activity for NKA was higher than that for SP and the inhibitory effect of the mixture for NKA was more marked than that for SP. Although some other fractions obtained from homogenates of spinal cords showed higher degrading activities for SP, these activities were insensitive to the mixture of peptidase inhibitors. 6. Effects of individual peptidase inhibitors on the enzymatic degradation of SP and NKA by synaptic membrane fractions were examined. Thiorphan, actinonin and captopril inhibited SP degradation, while thiorphan and actinonin, but not captopril, inhibited NKA degradation. The potency of the inhibition of each peptidase inhibitor was lower than that of the mixture.7. The present results suggest that enzymatic degradation is involved in the inactivation of tachykinin neurotransmitters in the spinal cord of the neonatal rat.

ECE-1: a membrane-bound metalloprotease that catalyzes the proteolytic activation of big endothelin-1

Endothelin-1 (ET-1), a 21-residue vasoactive peptide, is produced in vascular endothelial cells from the 38-residue inactive intermediate big endothelin-1 via a specific cleavage at Trp-21-Val-22. The protease that catalyzes the conversion, endothelin-converting enzyme (ECE), constitutes a potential regulatory site for the production of the active peptide. We report the identification of ECE-1, a novel membrane-bound neutral metalloprotease that is expressed abundantly in endothelial cells in vivo and is structurally related to neutral endopeptidase 24.11 and Kell blood group protein. When transfected into cultured cells that normally secrete only big ET-1, the ECE-1 cDNA conferred the ability to secrete mature ET-1. In transfected cells, ECE-1 processes endogenously synthesized big ET-1 as well as exogenously supplied big ET-1, which interacts with ECE-1 on the cell surface. ECE-1 may provide a target for pharmacological intervention to alter ET-1 production.

Effects of tumour necrosis factor alpha and interleukin 1 beta on the proliferation of cultured glomerular epithelial cells

Rat glomerular epithelial cells were cultured with human monocyte supernatant or with recombinant cytokines. A primary glomerular culture and a glomerular epithelial cell culture were made; supernatant from monocyte cultures derived from healthy humans, and recombinant tumour necrosis factor alpha (TNF alpha) or recombinant interleukin 1 beta (IL-1 beta) were added. Cell proliferation rates were assayed by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. In serum-free media, consistent proliferation of glomerular epithelial cells (GEC) was observed throughout the 3 week culture period. Significant growth-stimulatory effects were induced by lipopolysaccharide-treated monocyte conditioned medium and by 1-50 ng/ml of TNF alpha, growth being up to 400% more than in the control culture. The effect of TNF alpha depended mainly on its interaction with epidermal growth factor (EGF). In contrast to TNF alpha, IL-1 beta inhibited GEC proliferation; this was due to the early appearance and proliferation of mesangial cells, despite the culture being serum-free. This study showed that activated monocytes secrete growth factors for GEC in vitro, and that interaction between both TNF alpha and IL-1 beta and between TNF alpha and EGF can modulate GEC proliferation. These findings suggest that, under pathological conditions, monocytes or macrophages affect GEC proliferation, probably being involved in crescent formation.

Hepatic calcification in an anicteric patient with biliary atresia after hepatic portoenterostomy

Hepatic calcification was found in an anicteric infant with biliary atresia after hepatic portoenterostomy. When she was 2 years of age, ultrasonography detected an echogenic structure with acoustic shadowing. Computerized tomography located it at the proximal portion of Segment 6 in the right lobe. Although both techniques failed to exhibit dilatation of the peripheral bile ducts, we believe intrahepatic cholelithiasis provides the most likely diagnosis. Although seven cases with biliary atresia were reported to have this complication, all of them were icteric when the diagnosis was confirmed. The patient should be carefully followed up since the succeeding stones may cause jaundice by obstructing the main duct.

Fusarium merismoides Corda NR 6356, the source of the protein kinase C inhibitor, azepinostatin. Taxonomy, yield improvement, fermentation and biological activity

Fungal strain NR 6356, Fusarium merismoides Corda, was discovered as the source of the protein kinase C (PKC) inhibitor, azepinostatin. The strain was identified based on its growth on potato sucrose agar, slender conidial shape, characteristic polyphialide and production of abundant chlamydospores. Fusarium aquaeductuum Lagh. IMI 103658 and Fusarium sp. NR 7222 were also found to produce the same inhibitor. After single colony isolation and medium optimization trials, a more than 30-fold increase in the production of azepinostatin over the original culture was achieved. Azepinostatin selectively and potently inhibited rat brain PKC with an IC50 value of 70 nM. Other enzymes utilizing ATP, including hexokinase, were not affected. The Ki of azepinostatin for PKC was 0.5 nM. The inhibition of PKC was competitive with ATP and uncompetitive with histone.

Human melanoma cells express functional endothelin-1 receptors

Current evidence suggests that endothelium-derived factors enhance human melanoma vascular invasion. Therefore, we studied human melanoma cell expression of receptors to the endothelium-derived peptide, endothelin-1 (ET-1), and determined if they respond to ET-1 with proliferation and chemokinesis. Human metastatic melanoma cell lines were found to have specific, saturable, high affinity ET-1 binding. Northern analysis and competitive inhibition studies confirmed that melanoma cells express the ETB receptor isoform. Ten nanomolar ET-1 caused an 8.2 to 25.5-fold increase in intracellular free calcium. ET-1 was found to be a weak mitogen for melanoma cells, however, melanoma cell chemokinesis was significantly increased by ET-1. These data suggest that ET-1 may be involved in providing a chemokinetic and growth factor environment that enhances perivascular proliferation and invasiveness of melanoma cells.

Left ventricular contractile state in preterm infants: relation between wall stress and velocity of circumferential fiber shortening

Fetal and newborn lambs' hearts have limited capacity to adapt to increased afterload. In human preterm infants, however, this limited left ventricular pump function has not been investigated. To determine the normal left ventricular resting contractile state in preterm infants, we studied the relation of end-systolic wall stress to the rate-corrected velocity of circumferential fiber shortening (VCF) in 11 preterm infants of gestational ages 28 to 36 weeks. We performed the first (7 to 14 days of postnatal age) and the second (29 to 39 days of postnatal age) examinations. There was a significant inverse linear correlation between wall stress and VCF in the first and the second examinations (r = -0.616 and r = -0.715, respectively). Both regression lines had slopes that were steeper than those previously reported for older age groups. The preterm infants had high VCF values (mean 1.05 and 1.09 cir/sec, respectively) and low-wall stress values (mean 36.0 and 36.9 gm/cm2, respectively) in the first and the second examinations. We therefore suggest that the preterm infants have a high resting contractile state, but left ventricular performance may deteriorate in the face of increased afterload.

Pseudo-noncompetitive antagonism by BQ123 of intracellular calcium transients mediated by human ETA endothelin receptor

The family of endothelins, endothelin-1 (ET-1), ET-2 and ET-3, act on two subtypes of receptors called ETA and ETB receptors. BQ123 is an ETA-selective competitive antagonist. In this study, however, BQ123 inhibited ET-1-induced transients of cytosolic Ca2+ concentrations ([Ca2+]i) in an apparently noncompetitive manner in mouse L cell stably expressing cloned human ETA receptor. BQ123 (3-30 nM) did not change the EC50 of ET-1 (6.6 nM), but reduced the maximum responses down to 15.0%. In an non-equilibrium binding assay which mimicks the conditions of [Ca2+]i transient assay (cells were incubated with [125I]ET-1 only for 30 s), BQ123 (30 nM) constantly decreased the specific [125I]ET-1 binding to approximately 13% of that without the antagonist. Thus, the apparent noncompetitive antagonism by BQ123 of ETA receptor-mediated [Ca2+]i transient is due to the assay condition where the interactions of the agonist, antagonist and receptor remained non-equilibrium state.

Endotoxin and pro-inflammatory cytokines stimulate endothelin-1 expression and release by airway epithelial cells

Endothelin is a potent bronchoconstrictor peptide first identified as a novel vasoconstrictor produced by vascular endothelial cells. Recent reports suggest that airway epithelial cells are also capable of releasing this active peptide. To investigate the regulatory mechanism of endothelin expression, we studied the effects of endotoxin and pro-inflammatory cytokines such as interleukin-1 and tumour necrosis factor on the expression and release of endothelin-1 by airway epithelial cells. Both endotoxin and the cytokines stimulated endothelin-1 release by human bronchial epithelial cells. Northern blot analysis showed increased expression of preproendothelin-1 mRNA by these factors. These results suggested that airway epithelial cells might play a role in the local airway smooth muscle tone through the production of endothelin, which might be upregulated by inflammatory products in the airways.

Heparin suppresses endothelin-1 peptide and mRNA expression in cultured endothelial cells of spontaneously hypertensive rats

Heparin given sc consistently lowers blood pressure in spontaneously hypertensive rats (SHR). This study was designed to examine heparin's effect on vasoconstrictor endothelin-1 production in cultured aortic endothelial cells (EC). Aortic EC from SHR and normotensive Wistar Kyoto rats (WKY) were cultured and incubated with or without different concentrations of heparin. Heparin suppressed endothelin-1 release and endothelin-1 mRNA expression in a dose- and a time-dependent fashion in both WKY and SHR. The suppressive effects were more augmented in SHR than in WKY: SHR versus WKY--endothelin-1 level at 6 h = 8 +/- 1.8 versus 14 +/- 2.2 pg/10(6) cells (P < 0.01) and mRNA expression--85 versus 52% maximal inhibition by heparin, 10 U/mL (=70 micrograms/mL) (P < 0.01). When heparin was added with transcriptional inhibitor actinomycin D and incubated for 30 min, no further inhibition of endothelin-1 mRNA level measured after another 30 minutes was observed compared with the endothelin-1 mRNA level in cultured EC of SHR treated with just actinomycin D at 30 min. These results suggest that heparin regulates endogenous endothelin-1 production by cultured EC, probably at the transcriptional level, and that this effect is more marked in SHR than in WKY.

Changes of the expression and distribution of retinoic acid receptors during neurogenesis in mouse embryos

The expression and distribution of three retinoic acid receptors, alpha, beta, and gamma, were investigated in the CNS of mouse embryos during development. mRNAs and protein of RAR-beta that were expressed in the spinal cord of the 12.5-day mouse embryo decreased during development but they were not decreased in the brain. The RAR-beta-positive cells were already present in the ventral region of the spinal cord of 10.5-day mouse embryos, gradually appeared in the dorsal region during development and then disappeared from the spinal cord after birth. In the brain, RAR-beta-positive cells were detected in the mesencephalon and rhombencephalon but not in the telencephalon of the 12.5-day mouse embryos. RAR-beta-positive cells were present in the hippocampus and cingulum but not in the neocortex of 14.5-day mouse embryos. Most neurons in the hippocampus of 16.5-day mouse embryos and the cortex of newborn mice were RAR-beta-positive. In the spinal cord, RAR-alpha mRNAs and proteins also decreased during development but more gradually than RAR-beta mRNAs and proteins. During development, the distributions of RAR-alpha and -beta in the spinal cord and brain did not differ substantially. The main difference was the appearance of a subtypes of RAR-alpha, a 52-kDa protein, in the brain of newborn mice. On the other hand, RAR-gamma proteins were only faintly detected in the spinal cord and the brain of the mice during the embryonal stages but these increased after birth. The distribution of RAR-alpha- or -beta-positive cells were consistent with the neurogenesis during development in the spinal cord and brain.

Afterload reduction by hydralazine in children with a ventricular septal defect as determined by aortic input impedance

Hydralazine was administered at cardiac catheterization to eight children with a ventricular septal defect (age: 2.2-8.8 years), and the extent of afterload reduction was determined using aortic input impedance and wall stress. The pulmonary to systemic blood flow ratio decreased from 2.2 +/- 0.8 to 1.8 +/- 0.4 (p < 0.05) and the pulmonary systemic resistance ratio increased from 0.11 +/- 0.08 to 0.13 +/- 0.10 (p < 0.05) after hydralazine administration. Hydralazine reduced mean aortic pressure and the amplitude of the late systolic peak of the aortic pressure wave. Peak flow velocity in the descending aorta increased from 62 +/- 14 to 81 +/- 24 cm/sec (p < 0.05). Peripheral resistance decreased significantly from 13.3 +/- 5.9 to 6.6 +/- 3.7 10(3) dyn sec/cm3 (p < 0.05). The modulus of the first harmonic, indicating pulse wave reflection, decreased from 1196 +/- 575 to 815 +/- 382 dyn sec/cm3 (p < 0.05). The characteristic impedance, indicating aortic stiffness, did not change. End-systolic wall stress decreased significantly from 54.4 +/- 16.7 to 34.8 +/- 10.2 g/cm2 (p < 0.01). Hydralazine acutely achieved afterload reduction by reducing both peripheral resistance and pulse wave reflection, and increased stroke volume.

Hispidospermidin, a novel phospholipase C inhibitor produced by Chaetosphaeronema hispidulum (Cda) Moesz NR 7127. I. Screening, taxonomy, and fermentation

A novel phospholipase C inhibitor, hispidospermidin, was discovered from a fungal culture broth. The producing fungus, NR 7127, formed abundant pycnidia on banana leaf agar under near UV light. The ostiolate pycnidia were dark colored with a short beak possessing numerous protruding setae. The conidiogeneous cells were phialidic. The conidia were hyaline, 1 septate, smooth and spindle-shaped. From these distinctive characteristics, this strain was identified as Chaetosphaeronema hispidulum (Cda) Moesz of the Coelomycetes. Hispidospermidin was produced in a 50-liter jar fermentor containing 2% glucose, 2% potato starch, 2% Toast soya, 0.5% yeast extract, 0.25% NaCl, 0.0005% ZnSO4.7H2O, 0.0005% CuSO4.5H2O, 0.0005% MnSO4.4H2O, 0.32% CaCO3, and 0.3% Nissan disfoam CA-115. Fermentation was conducted at 27 degrees C at an aeration rate of 30 liters/minute and agitated at 500 rpm for 95 hours. Maximum production yield of hispidospermidin was observed after 72 hours. Hispidospermidin inhibited rat brain phospholipase C at 16 microM of IC50. This is the first recorded discovery of a secondary metabolite from the genus Chaetosphaeronema.

Human primitive hematopoietic progenitor cells are more enriched in KITlow cells than in KIThigh cells

To clarify the phenotypes of various classes of human hematopoietic progenitor cells, we used a multicolor staining protocol in conjunction with CD34 and a newly developed mouse antihuman c-kit proto-oncogene product (KIT) monoclonal antibody (MoAb). We characterized three cell fractions in CD34+ cells that express KITlow and KIThigh cells in addition to KIT- cells. A clonogenic assay showed that most granulocyte-macrophage colony-forming cells (GM-CFC) were present in CD34+KIThigh populations, whereas erythroid burst-forming cells (BFU-E) were detected mainly in the CD34+KITlow population. CD34(+)-KIT- fraction contained a small number of BFU-E. Morphologic analysis showed that blast-like cells were more enriched in the CD34+KITlow fraction. KITlow cells contained CD34+CD38- cells that were considered to be very primitive progenitor cells, as determined by a replating assay. To clarify the biologic differences between both fractions, we examined the more primitive progenitor cell functions by assessing long-term culture-initiating cells (LTC-IC) on the stromal cells. At week 2, more CFC recovered from the culture in the fraction initiated with a CD34+KIThigh population. However, more LTC-IC were present during weeks 5 to 9 in the CD34+KITlow population. These results indicate that primitive progenitors are more enriched in the KITlow population and that the KIThigh population contains many GM-committed progenitor cells. We also showed that anti-KIT MoAb inhibited the ability of CD34+ cells to generate CFC on the stromal layer in the LTC system. This suppressive effect was more evident in the generation of BFU-E by CD34+KITlow cells. Moreover, we confirmed that CD34+KIThigh cells emerged from CD34+KITlow cells during coculture with allogeneic stromal cells or from liquid culture in the presence of stem cell factor (SCF), interleukin-6, and erythropoietin. These results emphasize the pivotal role of the KIT and SCF interaction in hematopoiesis and indicate that KITlow cells are more primitive than KIThigh cells.

Depression of primary afferent-evoked responses by GR71251 in the isolated spinal cord of the neonatal rat

1. The pharmacological profile of GR71251, a new tachykinin receptor antagonist, and its effect on the responses evoked by stimulation of primary afferent fibres were studied in isolated spinal cord preparations of neonatal rats. Potential changes were recorded extracellularly from a lumbar ventral root (L3-L5). 2. Bath-application of substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) at 0.01-3 microM to the spinal cord induced depolarization of the ventral root in normal artificial cerebrospinal fluid (CSF). The NK1 agonist, acetyl-Arg6-septide, and the NK3 agonist, senktide, at 0.01-3 microM, also had potent depolarizing actions whereas two NK2 agonists, beta-Ala8NKA4-10 and Nle10NKA4-10, showed little depolarizing effects at 1 microM. 3. GR71251 (0.3-3 microM) caused a rightward shift of the concentration-response curves for SP, acetyl-Arg6-septide and NKA with pA2 values of 6.14, 6.75 or 6.70, respectively. The effects of GR71251 were readily reversible within 15-30 min after its removal. By contrast, GR71251 (1-5 microM) had little effect on the depolarizing responses to NKB and senktide. 4. GR71251 (1-3 microM) did not depress the depolarizing responses to bombesin, neuromedin B and gastrin-releasing peptide in normal artificial CSF. 5. Application of capsaicin to the spinal cord induced a depolarizing response, which was partially depressed by GR71251 (3-10 microM). 6. In the isolated spinal cord preparation, intense electrical stimulation of a dorsal root evoked a slow depolarizing response of the contralateral ventral root of the same segment. A similar slow ventral root depolarization was evoked by electrical stimulation of the ipsilateral saphenous nerve in an isolated spinal cord-saphenous nerve preparation. GR71251 (0.3-10 microM) dose-dependently depressed these slow ventral root potentials.7. In the spinal cord-peripheral nerve preparation, conditioning stimulation of the saphenous nerve evoked an inhibition of the muscle nerve-evoked monosynaptic reflex lasting about 20 s. The late part of the inhibition was markedly depressed by GR71251 (1-3 microM).8. The present results indicate that GR71251 is a potent and specific antagonist for tachykinin receptors in the spinal cord. The present study further provides evidence for the involvement of SP and NKA in the slow ventral root depolarization and the prolonged inhibition of monosynaptic reflex that are evoked by primary afferent stimulation.

[Methylmalonic acidemia with bilateral MRI high intensities of the globus pallidus]

We report a patient with methylmalonic acidemia who developed an acute extrapyramidal disorder after severe ketoacidosis. The neurologic findings resulted from bilateral destruction of the globus pallidus. A 10-year-old girl was the term product of an uncomplicated pregnancy and delivery. Poor feeding and vomiting were noted after one month. She was hospitalized at 6 months of age with vomiting, coma and tachypnea. Analysis of urinary organic acids revealed a massive amount methylmalonic acid. She was not vitamin B 12-responsive and was maintained on a low-protein diet. At 33 months of age, she was able to walk and speak, but she developed acute severe ketoacidosis. Involuntary movements and spastic paraplegia became evident two days after admission. Subsequently, the patient has had metabolic ketoacidosis once or twice a year. Her intelligence quotient was 47. Neurologic examination revealed spastic paraplegia and generalized hypotonicity with mild dystonia. Some relief from dystonic symptoms has been obtained through the use of L-dopa. A brain CT scan at 5 years of age disclosed bilaterally symmetric lucencies of the globus pallidus. T2-weighted brain MRI at 8 years of age showed bilateral symmetric high intensities of the globus pallidus.

Usefulness of bone SPECT of the cervical spine: with special reference to separate visualization of the trachea and thyroid cartilage

We applied bone SPECT for the examination of the cervical spine. A three-head rotating gamma camera SPECT system was employed for this study. The SPECT image disclosed 42.7% of abnormal accumulations in the skeleton not seen with planar imagings. SPECT could separately visualize the trachea and thyroid cartilage and also provided interpretation of abnormality in the anterior part of the vertebral body being difficult with planar imagings only. The trachea cartilage was seen in 55.4% and the thyroid cartilage was seen in 47.3% of patients with anterior neck density in planar imagings. SPECT clarified that marked cervical curvature and diffuse high uptake by the skeleton might cause high intensity of the anterior neck in planar imagings in the case of non-pathological change. We concluded that bone SPECT is a useful diagnostic tool in detecting occult lesion in the skeleton and to rule out extraskeletal accumulations in examination of the cervical spine.

Heparin regulates endothelin production through endothelium-derived nitric oxide in human endothelial cells

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.