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C J Lowenstein

Publications and source records attributed to C J Lowenstein.

At least 55 records · Page 3Linked to original sources
PubMed1995

Induction of nitric oxide synthase activity by cytokines in ventricular myocytes is necessary but not sufficient to decrease contractile responsiveness to beta-adrenergic agonists.

Recent evidence has documented that increased activity of an inducible nitric oxide synthase (iNOS; type 2 NO synthase) in primary isolates of adult rat ventricular myocytes after exposure to soluble mediators in medium conditioned by lipopolysaccharide-activated macrophages is associated with a decrease in their contractile responsiveness to beta-adrenergic agonists. It remained unclear which specific inflammatory cytokines in this medium contribute to the induction of iNOS activity in myocytes and whether induction of iNOS would result in an obligatory decline in contractile function. Interleukin (IL)-1 beta and tumor necrosis factor-alpha (TNF-alpha) were both present in the lipopolysaccharide-activated macrophage-conditioned medium. However, only IL-1 receptor antagonist and not an anti-rat TNF-alpha antiserum diminished the extent of iNOS induction in myocytes exposed to this medium and prevented a decline in contractile responsiveness to isoproterenol. When recombinant cytokines were used, IL-1 beta, TNF-alpha, and IFN-gamma each induced iNOS activity in cardiac myocytes at 24 hours. However, only the combination of IL-1 beta and IFN-gamma reproducibly caused contractile dysfunction in cardiac myocytes. Among the constituents of the defined medium routinely used for maintenance of adult rat ventricular myocytes in primary culture, it was noted that insulin (10(-7) mol/L) was required for NO production, as detected by nitrite release in cytokine-pretreated myocytes, although insulin had no effect on the extent of induction of iNOS mRNA or maximal enzyme activity in myocyte cell lysates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1995

Prolonged in vivo hypoxia enhances nitric oxide synthase type I and type III gene expression in adult rat lung.

Prolonged hypoxia in the adult rat causes a decline in endothelium-derived nitric oxide (NO) production in the pulmonary circulation. To evaluate whether this is related to a decrease in endothelial NO synthase (NOS-III) expression, we determined the effects of hypobaric hypoxia (7 or 21 days) on NOS-III gene expression in adult rat lung. Neuronal NOS (NOS-I) expression was also examined; NOS-I has been immunohistochemically localized to rat bronchiolar epithelium. NOS-III and NOS-I mRNA abundance were assessed in reverse transcription-polymerase chain reaction assays and the proteins were evaluated by immunoblot analysis. After 7 and 21 days of hypoxia, there were increases in the steady-state levels of both NOS-III and NOS-I mRNA, rising 2.7- to 3.0-fold and 2.5- to 2.8-fold, respectively. These findings were confirmed by Northern analyses. In parallel, NOS-III and NOS-I protein abundance were also increased with hypoxia by 3.0- to 3.5-fold and 2.4- to 3.0-fold, respectively. NOS activity detected by [3H]arginine to [3H]citrulline conversion rose 109%. Thus, prolonged in vivo hypoxia causes enhancement of NOS-III and NOS-I gene expression in adult rat lung, indicating that the pulmonary expression of these genes is modulated in vivo. The increase in NOS-III expression does not explain the declines in pulmonary endothelial NO production previously observed following prolonged hypoxia in this model. Alternatively, the fall in NO production may be related to diminished NOS co-factor availability.

Amino Acid Oxidoreductases↗
PubMed1995

First place winner of the Conrad Jobst Award in the gold medal paper competition. Nitric oxide synthase inhibitors N-monomethylarginine and aminoguanidine prevent the progressive and severe hypotension associated with a rat model of pancreatitis.

The objective of this study was to determine whether the observed vascular collapse and other pathologic features of severe pancreatitis may be related to the induction of nitric oxide synthase (NOS). The rat model of pancreatitis reported by Schmidt et al. was employed. Rats in the experimental groups received pretreatment with known NOS inhibitors, N-Monomethylarginine (NMMA) or Aminoguanidine (AG). Controls included sham-operated rats without pancreatic insult and a diseased control group which received pretreatment with normal saline (NS). Arterial blood pressure was continuously recorded with a femoral arterial catheter connected to a transducer and monitor. Fluid resuscitation for hypotension followed a strict protocol with the administration of 5.0 cc NS for sustained decreases in systolic blood pressure (SBP) below 90 mm Hg at 5-minute intervals. Laboratory parameters and histopathology confirmed the induction of pancreatitis, with 6 to 15-fold increases in serum amylase levels and an average of approximately 20% decrease in serum ionized Ca++ levels. Immunohistochemical studies of the pancreas revealed that pancreatic insult resulted in the induction of NOS. Rats in the saline control group (n = 5) became hypotensive (SBP less than 90 mm Hg) between 3 and 4 hours post pancreatic insult and required an average of 110.0 cc (3-4 x blood volume) of NS fluid resuscitation. Rats which were not resuscitated (n = 5) did not survive.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗
PubMed1994

Elevated expression of Th1 cytokines and nitric oxide synthase in the lungs of vaccinated mice after challenge infection with Schistosoma mansoni.

C57BL/6 mice were vaccinated with irradiated cercariae of Schistosoma mansoni, and, at various times after challenge infection, total lung mRNA was isolated to assess the induction of several cytokines that previously had been shown in in vitro studies to be involved in the activation of macrophages and/or endothelial cells for nitric oxide (NO) production and killing of schistosomula. Vaccinated mice demonstrated a highly significant increase in IFN-gamma mRNA upon subsequent infection when compared with infected nonvaccinated controls. A similar, although less dramatic, increase in two other macrophage-activating cytokines, TNF-alpha and IL-2, also was observed. In contrast, although the Th2 cytokines IL-4, IL-5, IL-10, and IL-13 were elevated in challenged vaccinated animals, only IL-10 and IL-13 showed increases that were significant with respect to the mRNA levels observed in challenged controls. Neutralization of IFN-gamma reduced immunity in vaccinated animals and resulted in decreased IFN-gamma, IL-2, IL-10, TNF-alpha, and IL-12 p40 but markedly increased IL-4, IL-5, and IL-13 mRNA expression and serum IgE levels. Pulmonary NO synthase expression was elevated in immunized mice at a time at which immune elimination of schistosomula is believed to occur. Moreover, suppression of NO synthase activity with the inhibitor aminoguanidine reduced immunity, as measured by a 32 to 33% increase in worm burden. Together, these data support previous in vitro studies that suggest a role for NO in schistosomulum killing. Furthermore, the observation that the down-regulatory cytokines IL-4, IL-10, and IL-13 are induced together with IFN-gamma may provide an explanation for the failure of this vaccine to provide complete protection.

Amino Acid Oxidoreductases↗
PubMed1994

Cytokine-inducible nitric oxide synthase (iNOS) expression in cardiac myocytes. Characterization and regulation of iNOS expression and detection of iNOS activity in single cardiac myocytes in vitro.

Cellular constituents of heart muscle contain both constitutive and inducible nitric oxide (NO) signaling pathways that modulate the contractile properties of cardiac myocytes. The identities of the inducible NO synthase (iNOS) isoform(s) expressed in cardiac muscle, and of the specific cell types expressing iNOS activity, remain poorly characterized. We amplified a 217-base pair cDNA by reverse transcriptase-polymerase chain reaction from primary cultures of inflammatory cytokine-pretreated adult rat ventricular myocytes (ARVM) that was nearly identical to other iNOS cDNA sequences. Using this 217-base pair cDNA as a probe in Northern blots, we found no evidence of iNOS mRNA in control myocytes, but both interleukin-1 beta and interferon-gamma individually increased iNOS mRNA abundance in primary cultures of ARVM, with maximal expression at 12 h. The half-life of iNOS mRNA in actinomycin C1-treated cells was 4 h. Both dexamethasone and transforming growth factor-beta attenuated the induction of iNOS mRNA abundance and enzyme activity by IL-1 beta and INF gamma. Pretreatment with dexamethasone also abolished the induction of iNOS mRNA, but not the increase in GTP cyclohydrolase mRNA in purified cardiac myocytes from lipopolysaccharide-injected rats. In order to further characterize the specific cell type producing NO, we used a NO-specific porphyrinic/Nafion-coated microsensor to record NO release from a single, isolated ARVM pretreated with IL-1 beta and IFN gamma in L-arginine-depleted medium. NO release could be detected following microinjection of L-arginine in the vicinity of the cell juxtaposed to the NO microsensor, but not following microinjection of D-arginine, and not from ARVM pretreated with L-N-monomethylarginine. Cytokine-pretreated ARVM that had been maintained in L-arginine-depleted medium also exhibited a depressed contractile response to isoproterenol after addition of L-arginine, but not D-arginine. These results indicate that altered contractile function of cardiac myocytes following exposure to specific inflammatory cytokines is due to induction of myocyte iNOS.

Amino Acid Oxidoreductases↗
PubMed1994

Nitric oxide: a physiologic messenger.

PURPOSE: To review the physiologic role of nitric oxide, an unusual messenger molecule that mediates blood vessel relaxation, neurotransmission, and pathogen suppression. DATA SOURCES: A MEDLINE search of articles published from 1987 to 1993 that addressed nitric oxide and the enzyme that synthesizes it, nitric oxide synthase. STUDY SELECTION: Animal and human studies were selected from 3044 articles to analyze the clinical importance of nitric oxide. Descriptions of the structure and function of nitric oxide synthase were selected to show how nitric oxide acts as a biological messenger molecule. DATA EXTRACTION: Biochemical and physiologic studies were analyzed if the same results were found by three or more independent observers. DATA SYNTHESIS: Two major classes of nitric oxide synthase enzymes produce nitric oxide. The constitutive isoforms found in endothelial cells and neurons release small amounts of nitric oxide for brief periods to signal adjacent cells, whereas the inducible isoform found in macrophages releases large amounts of nitric oxide continuously to eliminate bacteria and parasites. By diffusing into adjacent cells and binding to enzymes that contain iron, nitric oxide plays many important physiologic roles. It regulates blood pressure, transmits signals between neurons, and suppresses pathogens. Excess amounts, however, can damage host cells, causing neurotoxicity during strokes and causing the hypotension associated with sepsis. CONCLUSIONS: Nitric oxide is a simple molecule with many physiologic roles in the cardiovascular, neurologic, and immune systems. Although the general principles of nitric oxide synthesis are known, further research is necessary to determine what role it plays in causing disease.

Animals↗
PubMed1994

Nitric oxide synthase type I and type III gene expression are developmentally regulated in rat lung.

The successful transition from fetal to neonatal life involves a marked decline in pulmonary vascular resistance which is modulated in part by endothelium-derived nitric oxide. To define the molecular processes which prepare the pulmonary circulation for nitric oxide mediation of vasodilatation at the time of birth, we determined the ontogeny of endothelial nitric oxide synthase (NOS-III) gene expression in lungs from fetal and newborn rats. Maturational changes in lung neuronal NOS (NOS-I) expression were also investigated; the latter isoform has been localized to rat bronchiolar epithelium. NOS proteins were examined by immunoblot analysis, and mRNA abundance was assessed in reverse transcription-polymerase chain reaction assays. Both NOS-III and NOS-I protein were detectable in 16-day fetal lung, they increased 3.8- and 3.1-fold, respectively, to maximal levels at 20 days of gestation (term = 22 day), and they fell postnatally (1-5 days). In parallel with the findings for NOS-III protein, NOS-III mRNA increased from 16 to 20 days gestation and fell after birth. In contrast, NOS-I mRNA abundance declined during late fetal life and rose postnatally. These findings were confirmed by Northern analyses. Thus NOS-III and NOS-I gene expression are developmentally regulated in rat lung, with maximal NOS-III and NOS-I protein present near term. The regulation of pulmonary NOS-III may primarily involve alterations in transcription or mRNA stability, whereas NOS-I expression in the maturing lung may also be mediated by additional posttranscriptional processes.

Aging↗
PubMed1994

Culture of pulmonary microvascular smooth muscle cells from intraacinar arteries of the rat: characterization and inducible production of nitric oxide.

Pulmonary arterial microvascular smooth muscle function governs many aspects of lung physiology and pathophysiology. Acutely, microvascular smooth muscle cells (SMC) modulate pulmonary vascular resistance; chronically, they contribute to vascular remodeling. Recent work has also suggested a possible immune function for pulmonary smooth muscle through cytokine-stimulated nitric oxide production. To facilitate study of the mechanisms underlying these functions, we have developed methods for isolating pulmonary arterial microvessels from the rat and culturing SMC from these vessels. The pulmonary arterial circulation was filled with a suspension of iron oxide in agar, and a subpleural tissue sample was obtained. The vessels were cleared of surrounding lung parenchyma by partial collagenase digestion, and the iron-containing arteries were separated magnetically. The diameter of the harvested arteries confirmed an intraacinar origin, and the cultured cells expressed smooth muscle isoforms of alpha-actin and myosin but did not take up acetylated low density lipoprotein. To assess a possible immune effector role for these cells, confluent monolayers were stimulated with cytokines and endotoxin. At 24 h, immunofluorescent staining for inducible nitric oxide synthase was prominent within these cells. Nitric oxide production, as measured by nitrite levels in the cell-conditioned medium, was also markedly elevated but reduced by adding NG-monomethyl-L-arginine. We conclude that rat pulmonary arterial microvascular SMC can be obtained by the iron oxide infusion method and that these cells express an inducible nitric oxide synthase after cytokine stimulation.

Amino Acid Oxidoreductases↗
PubMed1994

Constitutive expression of inducible nitric oxide synthase in human bronchial epithelial cells induces c-fos and stimulates the cGMP pathway.

Two major roles have been defined for nitric oxide (NO): cell-cell communication mediated by the stimulation of cyclic guanosine 3',5'-monophosphate (cGMP) synthesis and cytotoxicity by direct or indirect interaction of the free radical NO with cellular targets. Thus, pathologic states might result from an alteration of NO pathways, e.g., by deregulated activity of NO synthase. To investigate this hypothesis, we introduced the murine-inducible NO synthase (iNOS) sequence into immortalized human bronchial epithelial cells (BEAS-2B). iNOS activity, measured by conversion of [14C]arginine to [14C]citrulline in the presence of 1 mM EGTA, was higher than 100 pmol/min/mg protein in early passages of iNOS-transfected cells but decreased with cell subculturing. No iNOS activity could be detected in control vector-transfected cells. NO stimulated cGMP production in iNOS-transfected cells, and this effect was inhibited by the iNOS inhibitor NG-monomethyl-L-arginine. In addition, NO production induced c-fos expression and did not interfere with clonal cell growth. These results suggest that BEAS-2B cells constitute a suitable model to study the consequences of iNOS activity on signal transduction pathways in bronchial epithelium.

Amino Acid Oxidoreductases↗
PubMed1993

Macrophage nitric oxide synthase gene: two upstream regions mediate induction by interferon gamma and lipopolysaccharide.

The promoter region of the mouse gene for macrophage-inducible nitric oxide synthase (mac-NOS; EC 1.14.13.39) has been characterized. A putative TATA box is 30 base pairs upstream of the transcription start site. Computer analysis reveals numerous potential binding sites for transcription factors, many of them associated with stimuli that induce mac-NOS expression. To localize functionally important portions of the regulatory region, we constructed deletion mutants of the mac-NOS 5' flanking region and placed them upstream of a luciferase reporter gene. The macrophage cell line RAW 264.7, when transfected with a minimal promoter construct, expresses little luciferase activity when stimulated by lipopolysaccharide (LPS), interferon gamma (IFN-gamma), or both. Maximal expression depends on two discrete regulatory regions upstream of the putative TATA box. Region I (position -48 to -209) increases luciferase activity approximately 75-fold over the minimal promoter construct. Region I contains LPS-related responsive elements, including a binding site for nuclear factor interleukin 6 (NF-IL6) and the kappa B binding site for NF-kappa B, suggesting that this region regulates LPS-induced expression of the mac-NOS gene. Region II (position -913 to -1029) alone does not increase luciferase expression, but together with region I it causes an additional 10-fold increase in expression. Together the two regions increase expression 750-fold over activity obtained from a minimal promoter construct. Region II contains motifs for binding IFN-related transcription factors and thus probably is responsible for IFN-mediated regulation of LPS-induced mac-NOS. Delineation of these two cooperative regions explains at the level of transcription how IFN-gamma and LPS act in concert to induce maximally the mac-NOS gene and, furthermore, how IFN-gamma augments the inflammatory response to LPS.

Amino Acid Oxidoreductases↗
PubMed1993

Molecular cloning and expression of inducible nitric oxide synthase from human hepatocytes.

Nitric oxide is a short-lived biologic mediator for diverse cell types. Synthesis of an inducible nitric oxide synthase (NOS) in murine macrophages is stimulated by lipopolysaccharide (LPS) and interferon gamma. In human hepatocytes, NOS activity is induced by treatment with a combination of tumor necrosis factor, interleukin 1, interferon gamma, and LPS. We now report the molecular cloning and expression of an inducible human hepatocyte NOS (hep-NOS) cDNA. hep-NOS has 80% amino acid sequence homology to macrophage NOS (mac-NOS). Like other NOS isoforms, recognition sites for FMN, FAD, and NADPH are present, as well as a consensus calmodulin binding site. NOS activity in human 293 kidney cells transfected with hep-NOS cDNA is diminished by Ca2+ chelation and a calmodulin antagonist, reflecting a Ca2+ dependence not evident for mac-NOS. Northern blot analysis with hep-NOS cDNA reveals a 4.5-kb mRNA in both human hepatocytes and aortic smooth muscle cells following stimulation with LPS and cytokines. Human genomic Southern blots probed with human hep-NOS and human endothelial NOS cDNA clones display different genomic restriction enzyme fragments, suggesting distinct gene products for these NOS isoforms. hep-NOS appears to be an inducible form of NOS that is distinct from mac-NOS as well as brain and endothelial NOS isozymes.

Amino Acid Oxidoreductases↗
PubMed1993

Expression of the nitric oxide synthase gene in mouse macrophages activated for tumor cell killing. Molecular basis for the synergy between interferon-gamma and lipopolysaccharide.

Macrophages can become activated to kill both tumor cells and a variety of microbes. Results here show that synthesis of nitric oxide (NO), a mediator of many macrophage cytotoxic functions, was greatly increased when cells of the mouse macrophage cell line RAW 264.7 were costimulated with bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), compared to LPS alone. This increase paralleled increases in cytotoxicity. Northern analysis showed that increased production of NO was preceded by markedly enhanced expression of mRNA for the inducible form of macrophage NO synthase (mac-NOS), which catalyzes the synthesis of NO. Cycloheximide inhibited the induction of mac-NOS mRNA by IFN-gamma and LPS, indicating that expression of this mRNA required de novo protein synthesis. Elevated expression of mac-NOS mRNA was not due to an increase in its stability. Rather, the combination of IFN-gamma and LPS induced a much higher rate of transcription of the mac-NOS gene than did stimulation with LPS alone. These results provide one explanation of why priming and triggering stimuli, such as IFN-gamma and LPS, respectively, synergistically activate macrophages and may be applicable to explaining how IFN-gamma augments NO-dependent microbicidal activity in macrophages as well.

Amino Acid Oxidoreductases↗
PubMed1993

Cytokines, endotoxin, and glucocorticoids regulate the expression of inducible nitric oxide synthase in hepatocytes.

Nitric oxide (NO.) is a short-lived mediator which can be induced in a variety of cell types and produces many physiologic and metabolic changes in target cells. The inducible or high-output NO. synthase (NOS) pathway was first characterized in macrophages activated by lipopolysaccharide (LPS) and interferon gamma (IFN-gamma). Hepatocytes also express an inducible NOS following exposure to the combination of endotoxin (LPS) and tumor necrosis factor (TNF), interleukin 1 (IL-1), and IFN-gamma. In this study, to identify which of these cytokines, if any, was acting to induce the gene expression for hepatocyte NOS, we measured the levels of rat hepatocyte NOS mRNA by Northern blot analysis after stimulation by various combinations of endotoxin and cytokines in vitro. We found the mRNA for hepatocyte NOS to be a single band at approximately 4.5 kilobases which was maximally up-regulated (approximately 70-fold) by the combination of TNF, IL-1, IFN-gamma, and LPS. Abundance of NOS mRNA peaked 6-8 hr after stimulation and then declined by 25% at 24 hr. Unstimulated hepatocytes in vitro showed only a trace mRNA band after prolonged autoradiographic exposure. As single agents, TNF and IL-1 were the most effective inducers of hepatocyte NOS mRNA. Combinations of two or three stimuli revealed strong synergy between TNF, IL-1, and IFN-gamma. The increased mRNA levels correlated with elevated nitrogen oxide release and cGMP levels in the culture supernatants. Dexamethasone and cycloheximide inhibited induction of mRNA for hepatocyte NOS in a dose-dependent fashion. The addition of NG-monomethyl-L-arginine had no effect on mRNA levels but effectively blocked NO. formation. The inducible hepatocyte NOS mRNA was also detected in rat hepatocytes following chronic hepatic inflammation triggered by Corynebacterium parvum injection in vivo. These data demonstrate that the inducible NOS is functional in rat hepatocytes both in vitro and in vivo and that this pathway is under complex control. Endotoxin and inflammatory cytokines act synergistically to up-regulate gene expression for hepatocyte NOS, whereas glucocorticoids down-regulate the mRNA.

Amino Acid Oxidoreductases↗
PubMed1993

Nitric oxide synthase distribution in the enteric nervous system of Hirschsprung's disease.

BACKGROUND: Hirschsprung's disease is characterized histologically by aganglionosis and functionally by impaired relaxation of the gut. Nitric oxide has recently been described pharmacologically as a major inhibitory mediator in the gut musculature in laboratory animals. The present study hypothesized that NO could be involved in motility disorders of the human gut. The aim was to study the neuronal enzyme synthetizing NO in the ganglionic and aganglionic human gut. METHODS: Reduced nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry and immunohistochemistry with a specific polyclonal antiserum were used to examine NO synthase distribution in the enteric nervous system in six patients with Hirschsprung's disease and five control patients. RESULTS: NO synthase was selectively absent in the plexus area and in the musculature of the aganglionic segments, whereas moderate staining was observed in the hypertrophied nerve bundles in the submucosa. In contrast, in the ganglionic segment NO synthase was abundantly present, in a pattern similar to that of the normal colon. CONCLUSIONS: These findings suggest the involvement of NO in the physiopathology of Hirschsprung's disease.

Amino Acid Oxidoreductases↗
PubMed1993

Immunohistochemical localization of nitric oxide synthase in the autonomic innervation of the human penis.

An improved understanding of the physiology of penile erection has resulted from recent evidence that implicates nitric oxide as the principal mediator of erectile function. Previously, the neuroanatomy of erection in man was established with descriptions of the autonomic innervation of the pelvic organs and external genitalia. The basis upon which novel physiological concepts of erection relate to earlier neuroanatomical principles remains to be determined. In the present study these relationships were explored with nitric oxide synthase immunohistochemistry and reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry of select pelvic tissue specimens obtained from 4 men (3 at radical prostatectomy and 1 at autopsy). Nitric oxide synthase, the enzyme that catalyzes nitric oxide production, was identified in discrete neuronal locations, including the pelvic plexus, cavernous nerves and their terminal endings within the corporeal erectile tissue, branches of the dorsal penile nerves and nerve plexuses in the adventitia of the deep cavernous arteries. This distribution of nitric oxide synthase-containing nerves suggests that nitric oxide neuronally modulates local vascular smooth musculature of the penis. On this basis, nitric oxide is identified as a neuronal mediator of penile erection in man.

Aged↗
PubMed1993

Nitric oxide synthase in human and rat lung: immunocytochemical and histochemical localization.

Nitric oxide synthase (NOS) produces nitric oxide, a mediator of potential importance in numerous physiologic and inflammatory processes in the lung. We localized constitutive NOS (c-NOS) and inducible NOS (i-NOS) within lung tissue by immunoperoxidase labeling with specific antibodies or by histochemical demonstration of the characteristic NADPH diaphorase activity of NOS. We analyzed human airway (n = 4) or parenchyma (n = 10) specimens obtained from uninvolved areas of surgical tumor resections. We also studied human fetal lung samples (n = 6) and normal or inflamed (16 h after intratracheal LPS instillation) rat lung tissue. Immunostaining with anti-c-NOS identified c-NOS antigen in rat lung nerves, endothelium, and airway epithelium. Normal or inflamed rat macrophages were not stained. Human nerve elements and large-vessel endothelium showed immunostaining with the anti-c-NOS, but no labeling of the airway or alveolar epithelium was seen. Immunostaining with anti-i-NOS showed strong labeling of rat macrophages after LPS treatment, in vivo or in vitro, while normals were negative. Human alveolar macrophages were occasionally positive for i-NOS, especially in areas of chronic inflammation, which also showed focal immunolabeling of endothelium. Uniform labeling of epithelium in large, cartilaginous airways was found with anti-i-NOS in both human bronchi and normal rat trachea samples, suggesting a constitutive role for a NOS that shares epitope(s) with or is highly homologous to the inducible, macrophage type of NOS. Histochemical staining for NADPH diaphorase activity was consistent with immunolocalization of NOS antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗