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Biomedical subjects

M Suematsu

Publications and source records attributed to M Suematsu.

At least 55 records · Page 3Linked to original sources
PubMed1999

Chronic inflammation upregulates chemokine receptors and induces neutrophil migration to monocyte chemoattractant protein-1.

Monocyte chemoattractant protein-1 (MCP-1) is a CC chemokine that stimulates monocyte recruitment when injected into tissues of healthy animals. However, the function of this chemokine in models with preexisting inflammation is not known. Therefore, MCP-1 was superfused over the mesentery of naive rats or rats with chronic adjuvant-induced vasculitis. MCP-1 elicited increased leukocyte transendothelial migration in adjuvant-immunized rats compared with naive animals. Surprisingly, histology revealed that neutrophils constituted the majority of leukocytes recruited in adjuvant-immunized animals. In vitro, MCP-1 was also able to induce chemotaxis of neutrophils isolated from adjuvant-immunized rats but not from naive rats. Flow cytometry revealed novel expression of the CC chemokine receptors CCR1 and CCR2 on neutrophils from adjuvant-immunized animals. In naive animals, an antibody against CD18 blocked leukocyte adhesion and emigration in response to MCP-1. In adjuvant-immunized animals, leukocyte adhesion was reduced by antibodies against the alpha4-integrin but not by antibodies against CD18. However, the CD18 antibody did block emigration. To our knowledge, this study is the first to show increased sensitivity to a CC chemokine in a model with preexisting inflammation, and altered leukocyte recruitment profiles in response to MCP-1. It also demonstrates that CD18 is required for chemokine-induced leukocyte transendothelial migration, independent of its known role in mediating firm adhesion. J. Clin. Invest. 103:1269-1276 (1999).

Animals↗
PubMed1999

Development of functional zonation in the rat adrenal cortex.

In an attempt to elucidate the mechanism(s) through which the functional adrenal cortex is established, we analyzed immunohistochemically the expression of various markers for the adrenocortical zones, i.e. the zona glomerulosa (zG), the zona fasciculata (zF), and the zona reticularis (zR), as well as markers for the medulla, and further examined the distribution and behavior of DNA-synthesizing cells in rat adrenal glands during development. The results showed that 1) separation of the cortex and medulla, and the development of functional zonation in the cortex began at around the time of birth, 2) at fetal stages when cortical zonation was not established, DNA-synthesizing cells were found scattered throughout the gland, where they proliferated without significant migration, and 3) after birth in the adrenal cortex with established cortical zonation, DNA-synthesizing cells were localized near the undifferentiated zone between zG and zF, and then they migrated centripetally. Cell death appeared to occur in the innermost portion of the cortex, where many resident macrophages are present. These findings illustrate basic processes underlying adrenal development and suggest that the undifferentiated region is apparently the stem cell zone of the adrenal cortex that maintains the cortical zonation.

Adrenal Glands↗
PubMed1999

Nitric oxide inhibits microvascular protein leakage induced by leukocyte adhesion-independent and adhesion-dependent inflammatory mediators.

OBJECTIVE: The purpose of this study was to determine whether exogenous nitric oxide could block permeability alterations induced by neutrophil-independent (histamine) and neutrophil-dependent (CINC/gro) inflammatory mediators. METHODS: Intravital microscopy was used in the rat mesentery to examine leukocyte adhesion, transvascular FITC-albumin leakage, and perivascular mast cell activation (ruthenium red uptake) in response to local superfusion with histamine or the chemokine CINC/gro. The effects of the nitric oxide donor spermine-NO, or the cGMP analog 8-Br-cGMP were examined. RESULTS: Histamine superfusion increased vascular protein leakage within minutes, but did not increase firm adhesion above that seen in control preparations. The increase in albumin leakage could be prevented by co-administration of spermine-NO, but was not affected by 8-Br-cGMP. CINC/gro elicited a linear increase in vascular protein leakage and a profound increase in leukocyte adhesion. Treatment with spermine-NO or 8-Br-cGMP significantly attenuated increases in both adhesion and albumin leakage. The actions of spermine-NO and 8-Br-cGMP were not due to mast cell stabilization as neither histamine nor CINC/gro elicited mast cell activation. CONCLUSIONS: This study demonstrates that exogenous nitric oxide and 8-Br-cGMP could block adhesion dependent alterations in vascular permeability induced by CINC/gro, while adhesion-independent alterations in permeability induced by histamine could be blocked by exogenous NO but not 8-Br-cGMP. This suggests that different NO-dependent signalling pathways are important in modulating these two types of vascular protein leakage.

Animals↗
PubMed1999

Microvascular oxidative stress, immune reaction and apoptosis in hypertensives.

The mechanisms that lead to organ injury in hypertension are incompletely understood. In particular, there is a lack of evidence that serves to link the elevation of arterial blood pressure with end organ damage. Experimental models of hypertension have a range of microvascular abnormalities in addition to a shift in blood pressure. There is evidence for an oxidative stress in microvascular endothelium derived from xanthine and NADPH oxidase. Furthermore, there exists an immune suppression accompanied by abnormally elevated circulating leukocyte counts, depression of selectin membrane adhesion to the endothelium and enhanced cell apoptosis. Many of the deficiencies in the spontaneously hypertensive rats can be corrected by adrenalectomy, suggesting a contribution of glucocorticoids to the abnormalities in this model. These observations suggest a significantly enhanced vascular oxidative stress which is accompanied by a frustrated inflammatory response due to a glucocorticoid dependent deficiency of leukocyte adhesion to vascular endothelium.

Animals↗
PubMed1998

Xanthine oxidase activity associated with arterial blood pressure in spontaneously hypertensive rats.

Recent evidence in vivo indicates that spontaneously hypertensive rats (SHR) exhibit an increase in oxyradical production in and around microvascular endothelium. This study is aimed to examine whether xanthine oxidase plays a role in overproduction of oxidants and thereby may contribute to hypertensive states as a consequence of the increasing microvascular tone. The xanthine oxidase activity in SHR was inhibited by dietary supplement of tungsten (0.7 g/kg) that depletes molybdenum as a cofactor for the enzyme activity as well as by administration of (-)BOF4272 [(-)-8-(3-methoxy-4-phenylsulfinylphenyl)pyrazolo(1,5-alpha)-1,3, 5-triazine-4-monohydrate], a synthetic inhibitor of the enzyme. The characteristic elevation of mean arterial pressure in SHR was normalized by the tungsten diet, whereas Wistar Koto (WKY) rats displayed no significant alteration in the pressure. Multifunctional intravital videomicroscopy in mesentery microvessels with hydroethidine, an oxidant-sensitive fluoroprobe, showed that SHR endothelium exhibited overproduction of oxyradicals that coincided with the elevated arteriolar tone as compared with WKY rats. The tungsten diet significantly repressed these changes toward the levels observed in WKY rats. The activity of oxyradical-producing form of xanthine oxidase in the mesenteric tissue of SHR was approximately 3-fold greater than that of WKY rats, and pretreatment with the tungsten diet eliminated detectable levels of the enzyme activity. The inhibitory effects of the tungsten diet on the increasing blood pressure and arteriolar tone in SHR were also reproducible by administration of (-)BOF4272. These results suggest that xanthine oxidase accounts for a putative source of oxyradical generation that is associated with an increasing arteriolar tone in this form of hypertension.

Animals↗
PubMed1998

Distribution of heme oxygenase isoforms in rat liver. Topographic basis for carbon monoxide-mediated microvascular relaxation.

Carbon monoxide (CO) derived from heme oxygenase has recently been shown to play a role in controlling hepatobiliary function, but intrahepatic distribution of the enzyme is unknown. We examined distribution of two kinds of the heme oxygenase isoforms (HO-1 and HO-2) in rat liver immunohistochemically using monoclonal antibodies. The results showed that distribution of the two isoforms had distinct topographic patterns: HO-1, an inducible isoform, was observed only in Kupffer cells, while HO-2, a constitutive form, distributed to parenchymal cells, but not to Kupffer cells. Both isoforms were undetectable in hepatic stellate cells and sinusoidal endothelial cells. Of the two isoforms, HO-2 in the parenchymal cell rather than HO-1 in the Kupffer cell, appears to play a major role in regulation of microvascular tone. In the perfused liver, administration of HbO2, a CO-trapping reagent that can diffuse across the fenestrated endothelium into the space of Disse, elicited a marked sinusoidal constriction, while administration of a liposome-encapsulated Hb that cannot enter the space had no effect on the microvascular tone. These results suggest that CO evolved by HO-2 in the parenchymal cells, and, released to the extrasinusoidal space, served as the physiological relaxant for hepatic sinusoids.

Animals↗
PubMed1998

Nitric oxide suppression reversibly attenuates mitochondrial dysfunction and cholestasis in endotoxemic rat liver.

This study aimed to examine whether nitric oxide (NO) plays a causal role in endotoxin-induced dysfunction of biliary transport. Rats were treated with intraperitoneal injection of endotoxin (O111B4, 4 mg/kg). At 2 hours, the liver was excised and perfused ex vivo with taurocholate (TC)-containing Krebs-Ringer solution under monitoring bile output and NO2 in the perfusate and tissue cyclic guanosine monophosphate (cGMP) levels as indices of NO production. The endotoxin treatment evoked a marked decrease in the bile acid-dependent bile formation concurrent with the increasing NO2 output, cGMP elevation, and a reduction of hepatic adenosine triphosphate (ATP) contents and oxygen consumption. Perfusion with 1 mmol/L aminoguanidine (AG), an inhibitor of inducible NO synthase, but not with L-nitroarginine methyl ester, an inhibitor of the constitutive form of the enzyme, significantly reversed the endotoxin-induced increment of the bile formation in concert with the recovery of oxygen consumption and ATP levels. Laser confocal microfluorography of the liver lobules using rhodamine 123 (Rh), a fluoroprobe sensitive to mitochondrial membrane potential, revealed that endotoxin elicited a significant mitochondrial dysfunction panlobularly. The AG administration reversed the endotoxin-induced decrease in mitochondrial membrane potential. Collectively, up-regulation of NO by inducible NO synthase accounts for a mechanism through which endotoxin impairs the bile formation, and its suppression serves as a therapeutic strategy for improvement of hepatobiliary function.

Animals↗
PubMed1998

Carbon monoxide as a regulator of bile canalicular contractility in cultured rat hepatocytes.

This study aimed to examine the mechanism(s) by which carbon monoxide (CO), a product of heme oxygenase reaction, controls the contractility of bile canaliculus (BC) in hepatocytes. When BCs associated with the couplet cells in cultured rat hepatocyte suspension were observed using time-lapse video microscopy, they exhibited periodical contractions with a most-probable interval of 6 minutes under our experimental conditions. The addition of 1 micromol/L zinc protoporphyrin IX (ZnPP), a potent inhibitor of heme oxygenase, to the culture medium elicited a 40% shortening of the interval time together with an increase in intracellular calcium concentrations, while the same concentration of iron protoporphyrin IX did not induce such changes. The production of CO, which was 0.5 nmol/h/10(8) cells in the absence of ZnPP, diminished to less than 0.1 nmol/h/10(8) cells upon application of ZnPP. The ZnPP-elicited increases in both contractile frequency and intracellular calcium concentrations were attenuated by the addition of 1 micromol/L CO or 50 micromol/L 1,2-bis(2-aminophenoxy) ethane-tetraacetate, a calcium chelator. Clotrimazole or metyrapone, inhibitors of cytochrome P450-dependent monooxygenase activities, also attenuated the ZnPP-induced elevation of the contractile frequency. On the other hand, intracellular cyclic guanosine monophosphate (cGMP) contents were not altered significantly by the application of ZnPP or by CO. These results indicate that CO generated by heme oxygenase controls the BC function by changing intracellular calcium concentrations presumably through a mechanism involving the cytochrome P450 reaction.

Animals↗
PubMed1998

Discontinuous total parenteral nutrition prevents postischemic mitochondrial dysfunction in rat liver.

Although discontinuous total parenteral nutrition (d-TPN) has recently been favored for clinical use over continuous total parenteral nutrition (c-TPN) to ameliorate liver dysfunction, mechanisms for the protection against postoperative liver dysfunction remain unknown. This study aimed to examine differences in mitochondrial function in d-TPN- and c-TPN-pretreated livers during ischemia-reperfusion. Rat livers pretreated with d-TPN or c-TPN were perfused with Krebs-Ringer buffer and were exposed to 25% low-flow hypoxia followed by reperfusion. Intrahepatic mitochondrial membrane potential (triangle up) and cell viability were assessed by dual-color digital microfluorography using rhodamine 123 (Rh123) and propidium iodide (PI), respectively. In response to hypoxia, livers pretreated with c-TPN, d-TPN, and an ordinary chow diet exhibited a significant triangle up reduction among the entire lobules. Upon reperfusion, the regional triangle up values further decreased in the c-TPN liver, whereas those in the d-TPN-treated or chow-treated livers displayed a rapid recovery toward the control levels. The severity of cell injury did not differ among the groups, showing that the reperfusion-induced triangle up drop in the c-TPN-pretreated liver is not a consequence of cell injury. Differences in the triangle up drop among the groups appear to occur irrespective of those in the glycogen storage, because the livers undergoing d-TPN display a marked triangle up recovery even when reperfused at the end of a fasted state. These results indicate that c-TPN, but not d-TPN, jeopardizes mitochondrial re-energization and suggest that a circadian pattern of the TPN serves as a potentially beneficial strategy to reduce the risk of postischemic mitochondrial dysfunction in the liver.

Animals↗
PubMed1998

Nitric oxide modulates T-lymphocyte migration in Peyer's patches and villous submucosa of rat small intestine.

BACKGROUND & AIMS: Although nitric oxide (NO) is known to influence the recruitment of neutrophils in inflamed tissue, its role in lymphocyte-endothelial cell interactions remains poorly understood. The objectives of this study were to assess the effects of NO synthesis inhibition on T-lymphocyte migration in microvessels of rat small intestine and to define the role of adhesion molecules in this process. METHODS: T lymphocytes collected from rat intestinal lymph were labeled with carboxyfluorescein diacetate succinimidyl ester and injected into the jugular vein of recipient rats. The migration of T lymphocytes into normal and NG-nitro-L-arginine methyl ester (L-NAME)-treated intestinal microvessels was monitored by using an intravital microscope. RESULTS: L-NAME significantly increased rolling and adherence of lymphocytes in postcapillary venules of Peyer's patches and submucosal venules without significantly decreasing red blood cell velocity. The subsequent appearance of lymphocytes in the initial lymphatics was also accelerated by L-NAME. Anti-4-integrin antibody markedly inhibited the L-NAME-induced lymphocyte-endothelial cell interaction. Anti-P-selectin monoclonal antibody also significantly attenuated these adhesive interactions in both vascular regions. CONCLUSIONS: These data suggest that NO is an important modulator of lymphocyte migration in Peyer's patches and in nonlymphoid regions of the intestine.

Animals↗
PubMed1998

Differential contribution of various adhesion molecules to leukocyte kinetics in pulmonary microvessels of hyperoxia-exposed rat lungs.

To elucidate the differential role of various adhesion molecules in distorting leukocyte behavior in the microvasculature of hyperoxia-exposed rat lungs, we investigated fluorescein-labeled leukocyte and erythrocyte kinetics in isolated lungs taken from the animals exposed to 90% O2 for 48 h under conditions in which endothelial intercellular adhesion molecule-1 (ICAM-1) and P-selectin were inhibited by appropriate monoclonal antibodies (1A29 for ICAM-1 and ARP2-4 for P-selectin), while leukocyte L-selectin was restrained with fucoidin. Measurements of blood cell kinetics were made by a confocal laser luminescence microscope coupled with a high-speed video camera. In addition, we histologically examined leukocyte accumulation within the alveolar septa and ICAM-1 as well as P-selectin expressions in the lung. We found that P-selectin expression was sparsely enhanced only in arterioles, whereas ICAM-1 was significantly induced in both venules and capillaries. Firm adhesion of leukocytes was not identified in arterioles and venules, whereas leukocyte rolling was evident in both the vessels. Arteriolar rolling was regulated via a P-selectin- and ICAM-1-independent but L-selectin-dependent mechanism, whereas venular rolling was mediated via a P-selectin-independent but ICAM-1- and L-selectin-dependent pathway. Leukocyte sequestration within capillaries was augmented by an ICAM-1-related mechanism. These findings may suggest that, in hyperoxia-exposed lungs, induction of adhesion molecules and their obstacles to leukocyte behavior are qualitatively different among arterioles, venules, and capillaries.

Animals↗
PubMed1998

[Changes in acetylcholine level and its related enzyme activities in rat brain following focal ischemia].

At 1 to 4 weeks following middle cerebral artery occlusion in Wistar rats, levels of acetylcholine, which is neuro-transmitter, were measured. In the hippocampus, which plays an important role in memory, levels of acetylcholine in the ischemic group could not be detected the significant difference compared with those in the sham-operated group. But in the anterior cortex and the caudate-putamen, levels of acetylcholine in the ischemic group were recognized the significant difference compared with those in the sham operated group. Moreover activities of choline acetyltransferase, which is the synthetic enzyme of acetylcholine, and activities of acetylcholinesterase, which is the degradative enzyme of acetylcholine, were measured in the anterior cortex which was recognized decrease of the acetylcholine level and the hippocampus which could not be detected the difference of the acetylcholine level. Activities of both enzymes in the hippocampus could not be recognized the significant difference between the ischemic group and the normal group. But in the anterior cortex activities of both enzymes in the ischemic group were significantly decreased compared with those in the normal group. These results suggest that these decreases in the ischemic group were due to damage of injection of cholinergic neuron from Meynert nucleus (basal nucleus of Meynert) to anterior cortex.

Acetylcholine↗
PubMed1998

Effect of rebamipide on H. pylori-associated gastric mucosal injury in Mongolian gerbils.

Helicobacter pylori colonized to gastric mucosa plays an important pathogenic role in gastric mucosal lesions. We previously reported that ethanol pretreatment promotes the extension of H. pylori-associated lesions. The present study was designed to examine the effect of rebamipide, a mucosal protective agent, on H. pylori-associated injury. Male Mongolian gerbils were orally inoculated with H. pylori; 30 min prior to inoculation, 40% ethanol was administered orally to these gerbils (Hp group). Controls were given 40% ethanol with culture medium (control group). Some gerbils in the Hp and control groups were fed rebamipide-containing diets, and the remaining gerbils received laboratory chow diets. H. pylori infection was evaluated by quantitative bacterial culture and histological examination. Although H. pylori was persistently detected and a remarkable mucosal leukocyte infiltration was observed in the Hp groups, the bacteria had disappeared naturally in 67% of the gerbils and mucosal damage was mitigated in the Hp + rebamipide group at four weeks after the inoculation. Collectively, rebamipide might play a role in inhibiting the level of H. pylori colonization and gastric lesion formation in Mongolian gerbils.

Alanine↗
PubMed1997

Disparity between serotonin- and acetylcholine-provoked coronary artery spasm.

BACKGROUND AND HYPOTHESIS: Intrinsic vasoactive substances, such as serotonin and acetylcholine, are known to provoke coronary artery spasm in patients with vasospastic angina. It remains unclear, however, whether these different agents, which activate different receptors, produce spasms at the same sites in these patients. The present study was designed to clarify the disparity of receptor agonist-induced coronary artery spasms in the same patients. METHODS: We conducted sequential provocative tests of coronary artery spasm by acetylcholine, serotonin, and ergonovine in 20 patients with rest angina examined with quantitative coronary angiography. RESULTS: Coronary artery spasms were provoked in all patients at 27 spastic sites. In 13 patients, ergonovine provoked spasms and in 10 of 13 patients who were diagnosed with variant angina, both acetylcholine and serotonin provoked spasms at the same sites where ergonovine also did. In 4 of 13 patients, spasms were provoked by serotonin but not by acetylcholine. In the remaining seven patients, whose spasms were induced by ergonovine, spasms were produced by acetylcholine but not by serotonin. On coronary angiography, the spastic sites for both acetylcholine and serotonin, and those for serotonin alone, were located in the proximal segments of coronary arteries, whereas the spastic sites for acetylcholine alone were located in the distal segments. CONCLUSIONS: This study documented the disparity between serotonin- and acetylcholine-induced spasms. Provocative tests using agents that activate different receptors may produce coronary artery spasms at the same and/or different sites, and this disparity may reflect the clinical heterogeneity of vasospastic ischemic syndrome.

Acetylcholine↗
PubMed1997

Behavior of stimulated leukocytes in the pulmonary microcirculation of perfused rat lungs.

To investigate the dynamics of activated leukocytes and the roles of CD18-ICAM-1 pathway, we examined the effects of rat IL-8 and monoclonal antibodies (mAbs) against CD18 and ICAM-1 on the behavior of leukocytes in microvessels of perfused rat lungs. Specific pathogen free male Sprague-Dawley rats were used. Perfused rat lungs were prepared so as to obtain stable physiological shear rates. We used a confocal laser scanning microscope equipped with a high speed video analysis system to visualize pulmonary microcirculation. Rat leukocytes were activated with rat IL-8. No rolling leukocytes were observed in either pulmonary arterioles or venules, and leukocytes were sequestered in capillaries. The majority of unstimulated capillary leukocytes moved smoothly. About 50% of stimulated leukocytes, however, showed a transient cessation of movement in pulmonary capillaries. Rat IL-8 decreased the relative leukocyte velocities against mean blood velocities in capillaries (45%) and venules (65%), and increased intracapillary neutrophils. Anti-CD18 and anti-ICAM-1 mAbs attenuated these changes. These results suggest that unique features exist in the interaction between activated leukocytes and pulmonary microvessels, and that CD18-ICAM-1-dependent capillary sequestration is one of the major mechanisms by which activated leukocytes accumulate in lungs.

Analysis of Variance↗
PubMed1997

Effect of lipopolysaccharides on erythrocyte flow velocity in rat liver.

Although endotoxin exacerbates hepatic microcirculatory disturbance, little is known of the way in which it acts on the hepatic microcirculation. We measured endotoxin-induced changes in hepatic microcirculation and investigated the effect of endotoxin on hepatic microcirculation in rats. After male Wistar rats were anesthetized, a lobe of the liver was observed with an inverted intravital microscope. Erythrocytes (RBC) were labeled with fluorescein isothiocyanate (FITC) and injected. The flow velocity (FV) of FITC-RBC in sinusoids was measured with an off-line velocimeter. Portal pressure (PP) and mean arterial pressure (MAP) were measured with a catheter cannulated in the portal vein and the left carotid artery, respectively. After a small dose (1 mg/kg) of endotoxin had been administered intravenously, FV decreased and PP increased gradually after 30 min. MAP showed no significant change, except for an initial decrease. However, when 5 mg/kg of endotoxin was administered, FV and PP increased, with a peak at 10 min, which was not observed with the small dose. In the late phase, FV decreased and PP increased, as was seen with the small dose. Endotoxin increased serum aspartate aminotransferase and lactate dehydrogenase activities. These results suggest that endotoxin induces hepatic microcirculatory disturbance, which may cause liver injury.

Alanine Transaminase↗
PubMed1997

Endothelial-derived nitric oxide preserves anticoagulant heparan sulfate expression in cultured porcine aortic endothelial cells.

Nitric oxide (NO) has been shown to inhibit platelet adhesion and aggregation, but there are no reports on its interaction with the coagulation system. We investigated the effect of the L-arginine analogues, N-nitro-L-arginine (LNA), N(G)-nitro-L-arginine methyl ester (L-NAME), and N(G)-monomethyl-L arginine (L-NMMA), competitive inhibitors of NO production, on endothelial-surface heparan sulfate. Addition of LNA to porcine aortic endothelial cells reduced 125I-labeled antithrombin III binding to the cell surface heparan sulfate in a dose- and time-dependent fashion. Significant inhibition was observed with 1 mM LNA, and the maximal suppression (-50% of control) occurred at 10 mM LNA after 12 h. L-NAME (1 mM) and L-NMMA (1 mM) also significantly inhibited the antithrombin III binding. The iron chelator desferrioxamine significantly prevented the reduction of antithrombin III binding to LNA-treated cells. We further investigated the effect of L-NAME on intracellular oxidative stress of endothelial cells using a hydroperoxide-sensitive fluorochrome, carboxy-dichloro-dihydrofluorescein diacetate bisacetoxymethyl ester probe, and revealed that inhibition of NO synthesis by L-NAME led to a marked increase in intracellular oxidative stress. These results demonstrated that the prolonged inhibition of NO synthesis in porcine aortic endothelial cells decreases the expression of anticoagulant heparan sulfate on endothelial cells through the increase in intracellular oxidative stress, perhaps comprising another mechanism by which NO affects the coagulation system in the vasculature.

Animals↗