Ciliostimulatory effects mediated by nitric oxide

The effects of sildenafil on ciliary beat frequency in patients with pulmonary non-tuberculous mycobacteria disease: phase I/II trial

Rationale

Pulmonary non-tuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Abnormal mucociliary clearance and abnormal nasal nitric oxide (nNO) have been associated with PNTM disease in other patient cohorts. Mucociliary clearance can be affected by NO-cyclic guanosine monophosphate signalling and, therefore, modulation of the pathway may be possible with phosphodiesterase inhibitors such as sildenafil as a novel therapeutic approach.

Objective

To define ex vivo characteristics of PNTM disease affected by sildenafil.

Methods

Subjects with PNTM infections were recruited into an open-label dose-escalation trial of sildenafil. Laboratory measurements and mucociliary measurements—ciliary beat frequency, nNO and 24-hour sputum production—were collected throughout the study period. Patients received sildenafil daily during the study period, with escalation from 20 to 40 mg three times per day.

Measurements and main results

Increased ciliary beat frequency occurred after a single dose of 40 mg sildenafil and after extended dosing of 40 mg sildenafil. The increase ciliary beat frequency was not seen with 20 mg sildenafil dosing. There were no changes in sputum production, nNO production, Quality of Life-Bronchiectasis-NTM module (QOL-B-NTM) questionnaire or the St George’s Respiratory Questionnaire during the study period.

Conclusion

Sildenafil, 40 mg, increased ciliary beat frequency acutely as well as with extended administration.

Effect of Nitric Oxide and Peroxynitrite on Mucociliary Transport Function of Experimental Otitis Media

OBJECTIVES: To determine the role of nitric oxide (NO) and peroxynitrite on mucociliary activity in experimental otitis media with effusion (OME).

STUDY DESIGN AND SETTING: Twenty guinea pigs were divided into 1 control and 3 experimental groups; lipopolysaccharide (LPS), NG-nitro-L-arginine methyl ester (L-NAME), and uric acid (UA) groups. Ten ears were used in each group. OME was induced by transtympanic injection of LPS in experimental groups. Twenty-four hours after the transtympanic injection, dye transfer time (DTT) was measured and the temporal bone was taken for histopathologic examination. Expression of peroxynitrite was determined by immunohistochemical stain for 3-nitrotyrosine (3-NT).

RESULTS: Dye transfer time was significantly delayed in LPS group compared to control group; by contrast it was significantly reduced in L-NAME or UA treated groups ( P < 0.01). Histopathologic examination showed reduced inflammation and mucosal thickening in the treatment groups when compared to LPS group. These findings, however, were not statistically significant. Immunoreactivity to 3-NT was intense in LPS group and decreased in the treatment groups ( P < 0.05).

CONCLUSIONS: It is suggested that LPS induced mucociliary dysfunction in the middle ear by NO and peroxynitrite-mediated pathways.

The effect of drugs and other compounds on the ciliary beat frequency of human respiratory epithelium

BACKGROUND

Cilia in the human respiratory tract play a critical role in clearing mucus and debris from the airways. Their function can be affected by a number of drugs or other substances, many of which alter ciliary beat frequency (CBF). This has implications for diseases of the respiratory tract and nasal drug delivery. This article is a systematic review of the literature that examines 229 substances and their effect on CBF.

METHODS

MEDLINE was the primary database used for data collection. Eligibility criteria based on experimental design were established, and 152 studies were ultimately selected. Each individual trial for the substances tested was noted whenever possible, including concentration, time course, specific effect on CBF, and source of tissue.

RESULTS

There was a high degree of heterogeneity between the various experiments examined in this article. Substances and their general effects (increase, no effect, decrease) were grouped into six categories: antimicrobials and antivirals, pharmacologics, human biological products, organisms and toxins, drug excipients, and natural compounds/other manipulations.

CONCLUSION

Organisms, toxins, and drug excipients tend to show a cilioinhibitory effect, whereas substances in all other categories had mixed effects. All studies examined were in vitro experiments, and application of the results in vivo is confounded by several factors. The data presented in this article should be useful in future respiratory research and examination of compounds for therapeutic and drug delivery purposes.

Cyclic GMP and Cilia Motility

Motile cilia of the lungs respond to environmental challenges by increasing their ciliary beat frequency in order to enhance mucociliary clearance as a fundamental tenant of innate defense. One important second messenger in transducing the regulable nature of motile cilia is cyclic guanosine 3′,5′-monophosphate (cGMP). In this review, the history of cGMP action is presented and a survey of the existing data addressing cGMP action in ciliary motility is presented. Nitric oxide (NO)-mediated regulation of cGMP in ciliated cells is presented in the context of alcohol-induced cilia function and dysfunction.

Abnormal nasal nitric oxide production, ciliary beat frequency, and Toll-like receptor response in pulmonary nontuberculous mycobacterial disease epithelium

RATIONALE

Pulmonary nontuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Despite extensive investigation, no consistent immunological abnormalities have been found. Using evidence from diseases such as cystic fibrosis and primary ciliary dyskinesia, in which mucociliary dysfunction predisposes subjects to high rates of nontuberculous mycobacterial disease that increase with age, we investigated correlates of mucociliary function in subjects with PNTM infections and healthy control subjects.

OBJECTIVES

To define ex vivo characteristics of PNTM disease.

METHODS

From 2009 to 2012, 58 subjects with PNTM infections and 40 control subjects were recruited. Nasal nitric oxide (nNO) was determined at the time of respiratory epithelial collection. Ciliary beat frequency at rest and in response to Toll-like receptor (TLR) and other agonists was determined using high-speed video microscopy.

MEASUREMENTS AND MAIN RESULTS

We found decreased nNO production, abnormally low resting ciliary beat frequency, and abnormal responses to agonists of TLR2, -3, -5, -7/8, and -9 in subjects with PNTM compared with healthy control subjects. The low ciliary beat frequency in subjects with PNTM was normalized ex vivo by augmentation of the NO-cyclic guanosine monophosphate pathway without normalization of their TLR agonist responses.

CONCLUSIONS

Impaired nNO, ciliary beat frequency, and TLR responses in PNTM disease epithelium identify possible underlying susceptibility mechanisms as well as possible avenues for directed investigation and therapy.

Bronchial epithelium as a target for innovative treatments in asthma

Increasing evidence of a critical role played by the bronchial epithelium in airway homeostasis is opening new therapeutic avenues. Its unique situation at the interface with the environment suggests that the subtle regulation orchestrated by the epithelium between tolerance and specific immune response might be impaired in asthma. Airway mucus is acting as a physical and a biological fluid between the environment and the epithelium, synergistically moved by the cilia. In asthma, excessive mucus production is a hallmark of airway remodeling. Since many years we tried to therapeutically target mucus hypersecretion, but actually this option is still not achieved. The present review discusses the dynamic processes regulating airway mucus production. Airway inflammation is central in current asthma management. Understanding of how the airway epithelium influences the TH2 paradigm in response to deleterious agents is improving. The multiple receptors expressed by the airway epithelium are the transducers of the biological signals induced by various invasive agents to develop the most adapted response. Airway remodeling is observed in severe chronic airway diseases and may result from ongoing disturbance of signal transduction and epithelial renewal. Chronic airway diseases such as asthma will require assessment of these epithelial abnormalities to identify phenotypic characteristics associated with predicting a clinical benefit for epithelial-directed therapies.

Effect of nitric oxide on epithelial ion transports in noncystic fibrosis and cystic fibrosis human proximal and distal airways

The airways of patients with cystic fibrosis (CF) exhibit decreased nitric oxide (NO) concentrations, which might affect airway function. The aim of this study was to determine the effects of NO on ion transport in human airway epithelia. Primary cultures of non-CF and CF bronchial and bronchiolar epithelial cells were exposed to the NO donor sodium nitroprusside (SNP), and bioelectric variables were measured in Ussing chambers. Amiloride was added to inhibit the Na+channel ENaC, and forskolin and ATP were added successively to stimulate cAMP- and Ca2+-dependent Cl−secretions, respectively. The involvement of cGMP was assessed by measuring the intracellular cGMP concentration in bronchial cells exposed to SNP and the ion transports in cultures exposed to 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one, an inhibitor of the soluble guanylate cyclase (ODQ), or to 8Z, a cocktail of 8-bromo-cGMP and zaprinast (phosphodiesterase 5 inhibitor). SNP decreased the baseline short-circuit current ( Isc) and the changes in Iscinduced by amiloride, forskolin, and ATP in non-CF bronchial and bronchiolar cultures. The mechanism of this inhibition was studied in bronchial cells. SNP increased the intracellular cGMP concentration ([cGMP]i). The inhibitory effect of SNP was abolished by 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, an NO scavenger (PTIO) and ODQ and was partly mimicked by increasing [cGMP]i. In CF cultures, SNP did not significantly modify ion transport; in CF bronchial cells, 8Z had no effect; however, SNP increased the [cGMP]i. In conclusion, exogenous NO may reduce transepithelial Na+absorption and Cl−secretion in human non-CF airway epithelia through a cGMP-dependent pathway. In CF airways, the NO/cGMP pathway appears to exert no effect on transepithelial ion transport.

Effects of nitric oxide in mucociliary transport

The airways are made up of ciliated epithelium which secretes mucous, protecting the respiratory tract from particles inhaled during breathing. Its is paramount to understand the physiology and the mechanisms involved in mucociliary activity. Literature suggests that Nitric oxide (NO), especially the one produced by iNOS expression, maintains the mucociliary function and the immune defense of the nasal cavity.

Aim

to assess NO participation and the enzymatic pathways in the production of NO and mucociliary transport, using constructive and inductive NO synthetase inhibitors, L-NAME and aminoguanidine, respectively.

Materials and methods

frog palates were prepared and immerse in ringer (control), L-NAME or aminoguanidine solutions. The palates were immerse in these solutions for four periods of 15 minutes. Mucociliary transport measures were carried out before and after each exposure.

Results

control palates maintained stable their transportation speed. L-NAME increased, while aminoguanidine reduced mucous transportation velocity.

Conclusion

unspecific cNOS block with L-NAME and relatively specific iNOS block with aminoguanidine results leads us to propose that depending on the pathway, the NO can increase or reduce mucociliary transport in frog palates.

Documentation of the nasal nitric oxide response to humming: methods evaluation

RATIONALE

Nitric oxide (NO) is present at higher concentrations in the nasal cavity than in the lower airway, and at even higher concentrations within the paranasal sinuses proper. When the paranasal sinus ostia are patent, acoustic activity produced by vocalization with closed lips (humming) promotes mixing of sinus with nasal gases, producing a further increase in nasal NO. We wished to evaluate procedures for the documentation of the nasal NO response to humming.

MATERIALS AND METHODS

We compared two ATS-recommended sampling methods: 1) active exhalation of lower airway gas (parallel technique) and 2) passive aspiration of nasal gas with closed velopharynx (series technique). Variables controlled for included sampling rate, external resistance (parallel method), humming frequency, humming duration, and intertrial interval. Prior to upper airway sampling, exhaled lower airway NO was determined utilizing ATS-standardized technique.

RESULTS

Ten volunteers (seven males and three females, aged 21-58) with no history of respiratory allergies or sino-nasal disease were studied in a single session each. The parallel technique documented an increase in nasal NO during the humming manoeuvre in all subjects (mean ratio of humming-to-quiet NO, 4.2), whereas the series technique did so in eight of 10 subjects (mean ratio 2.1). Correcting for admixture from the lower airway, the ratio of humming-to-quiet NO was greater with the parallel than series sampling technique (P < 0.05).

CONCLUSIONS

Documentation of the response of nasal NO to humming in subjects without sino-nasal disease was consistently achievable by parallel sampling using commercially available equipment. Specific operational procedures are proposed.

Caveolin-3 and eNOS colocalize and interact in ciliated airway epithelial cells in the rat

In ciliated airway epithelial cells endothelial nitric oxide synthase as well as several other membrane bound proteins are located in the apical cell pole. To date, mechanisms that serve to target and to keep these proteins in this region are unknown. Endothelial nitric oxide synthase is known to target to caveolae by interaction with caveolin-1 or caveolin-3. Since caveolin-1 is found only in a subpopulation of ciliated cells at the basolateral cell membrane, we examined if caveolin-3 could be responsible for the apical localization of endothelial nitric oxide synthase in ciliated cells. We used real-time RT-PCR, laser-assisted microdissection, Western blotting and double-labeling immunohistochemistry to examine the presence of caveolin-3 in the airway epithelium of the rat. Indeed, we found caveolin-3-mRNA as well as protein in ciliated cells throughout the trachea and the bronchial tree. Caveolin-3-immunoreactivity was confined to the apical region and was colocalized with endothelial nitric oxide synthase and the high affinity choline transporter in a compartment distinct from the plasma membrane at the light microscopic level. No caveolae were found in the apical plasma membrane of ciliated cells but a tubulovesicular network was present in the apical region that reached up to the basal bodies of the cilia and was in close contact with mitochondria. Co-immunoprecipitation of caveolin-3 with endothelial nitric oxide synthase verified that both proteins interact in airway ciliated cells. These findings indicate that caveolin-3 is responsible to keep endothelial nitric oxide synthase in a membrane compartment in the apical region of ciliated cells.

Nervous control of ciliary beating by Cl-, Ca2+ and calmodulin inTritonia diomedea

In vertebrates, motile cilia line airways, oviducts and ventricles. Invertebrate cilia often control feeding, swimming and crawling, or gliding. Yet control and coordination of ciliary beating remains poorly understood. Evidence from the nudibranch mollusc, Tritonia diomedea, suggests that locomotory ciliated epithelial cells may be under direct electrical control. Here we report that depolarization of ciliated pedal epithelial (CPE)cells increases ciliary beating frequency (CBF), and elicits CBF increases similar to those caused by dopamine and the neuropeptide, TPep-NLS. Further,four CBF stimulants (zero external Cl-, depolarization, dopamine and TPep-NLS) depend on a common mode of action, viz. Ca2+influx, possibly through voltage-gated Ca2+ channels, and can be blocked by nifedipine. Ca2+ influx alone, however, does not provide all the internal Ca2+ necessary for CBF change. Ryanodine receptor(RyR) channel-gated internal stores are also necessary for CBF excitation. Caffeine can stimulate CBF and is sensitive to the presence of the RyR blocker dantrolene. Dantrolene also reduces CBF excitation induced by dopamine and TPep-NLS. Finally, W-7 and calmidazolium both block CBF excitation by caffeine and dopamine, and W-7 is effective at blocking TPep-NLS excitation. The effects of calmidazolium and W-7 suggest a role for Ca2+-calmodulin in regulating CBF, either directly or via Ca2+-calmodulin dependent kinases or phosphodiesterases. From these results we hypothesize dopamine and TPep-NLS induce depolarization-driven Ca2+ influx and Ca2+ release from internal stores that activates Ca2+-calmodulin, thereby increasing CBF.

Silent and humming nasal NO measurements in adults aged 18-70 years

BACKGROUND

The concentration of nitric oxide (NO) measured from the nose is much higher than in the lower airways and increases during humming. We assessed nasal NO (nNO) normal values during breath hold and during humming in healthy adults.

MATERIALS AND METHODS

Nasal NO concentrations were measured in healthy adults (ages 18-70). They held their breath for 10 s and thereafter hummed as loud as possible with their mouths closed also for 10 s. During breath hold, air was passively extracted from one nostril with 700 mL min(-1). The average NO concentration at the plateau after 7-10 s was recorded and the mean of three consecutive measurements was calculated. During humming, air was extracted with 1200 mL min(-1), the peak NO values were recorded.

RESULTS

One hundred healthy adults participated (37 men). The nNO concentrations during breath hold were distributed normally (mean: 455 parts per billion (p.p.b.), SD 147). A random subgroup of 40 out of the 100 subjects (15 men) performed nNO measurement during humming. The median peak NO value was 1019 p.p.b. (SD 561) at the first, and 837 p.p.b. (SD 408) at the second measurement. There was a significant difference between the peak NO values of first and second humming.

CONCLUSION

We present normal values for nNO in adults, which can be used to assess the value of nNO in respiratory illnesses. The peak nNO values during humming are variable, and their clinical relevance remains to be shown.

Effect of isoproterenol on the regulation of rabbit airway ciliary beat frequency measured with high-speed digital and fluorescence microscopy

To investigate how isoproterenol, a beta-adrenergic agonist, regulates airway ciliary beat frequency (CBF), we simultaneously quantified changes in rabbit airway CBF and intracellular calcium concentration ([Ca2+]i) in response to isoproterenol (100 micromol/L) by using high-speed (240 frames per second) and fluorescence microscopy. At approximately 30 degrees C, isoproterenol induced a change in CBF that could be separated into two parts. First, isoproterenol induced a moderate increase in the basal CBF that was calcium-independent. This response was unaffected by buffering the [Ca2+]i with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrapotassium salt (BAPTA). Second, isoproterenol induced a transient increase in CBF that was superimposed on the increased basal CBF and correlated with a simultaneous transient increase in [Ca2+]i. This transient increase in CBF was abolished by BAPTA. We conclude that isoproterenol initially increases CBF through a calcium-independent mechanism, probably via protein kinase A, and subsequently through a calcium-dependent mechanism mediated by an increase in [Ca2+]i.

The effect of endogenous nitric oxide on cholinergic ciliary stimulation of human nasal mucosa

OBJECTIVES/HYPOTHESIS

Endogenous nitric oxide (NO) production by inducible nitric oxide synthase is enhanced in the nasal ciliated respiratory tract epithelium of patients with allergic rhinitis. Recent experimental data have suggested endogenous NO to be strongly involved in the complex regulation of ciliary activity, the driving force of the mucociliary transport system. The authors investigated the effect of endogenous NO on acetylcholine-stimulated ciliary activity of human nasal mucosa.

STUDY DESIGN

In vitro study.

METHODS

Cultures of human nasal mucosa explants were incubated with tumor necrosis factor-alpha and bacterial lipopolysaccharides to enhance endogenous NO production. Expression of inducible NO synthase was morphologically demonstrated by immunohistochemistry. Ciliary beat frequency was determined by phase-contrast microscopy of ciliated epithelium, using a computerized photoelectric technique. Stimulation experiments were performed in vitro with acetylcholine and N(G)-nitro-l-arginine methyl ester (L-NAME), a NO synthase inhibitor.

RESULTS

Upregulation of inducible NO synthase in the respiratory tract epithelium after stimulation with tumor necrosis factor-alpha and lipopolysaccharide was visualized by immunohistochemical analysis. Experimental inhibition of enhanced endogenous NO production by 10 mol/L L-NAME significantly reduced baseline ciliary beat frequency from 8.6 +/- 0.2 to 7.8 +/- 0.2 Hz (P < .05). Cholinergic ciliary stimulation above baseline by 10 mol/L acetylcholine was not significantly different before (11.5%) or after (10.8%) blocking of endogenous NO production.

CONCLUSION

Taken together, the study results suggest that baseline ciliary activity depends on endogenous NO production but that the extent of cholinergic ciliary stimulation is independent of endogenous NO production. The combination of the two effects may improve nasal mucociliary clearance of inhaled allergens in patients with allergic rhinitis.

New Insights Into the Pathogenesis of Cystic Fibrosis

The cystic fibrosis transmembrane regulator (CFTR) should no longer be viewed primarily as a 'chloride channel' but recognized as a channel that also controls the efflux of other physiologically important anions, such as glutathione (GSH) and bicarbonate. More effective approaches to cystic fibrosis treatment may result from this reconceptualization of the CFTR by researchers and clinicians. For example, oxidant damage in cystic fibrosis has been assumed to be a significant part of the pathophysiology of the disease. Generally speaking, antioxidant status in cystic fibrosis is compromised. However, until recently this was seen as secondary to the excessive chemoattraction of neutrophils in this disease caused by mutation of the CFTR protein, leading to a high oxidant burden. New findings suggest that the cystic fibrosis mutations in fact cause a primary dysfunction in the system of one of the body's most important antioxidant and immune-signaling substances: the reduced GSH system. Cystic fibrosis mutations significantly decrease GSH efflux from cells without redundant channels to the CFTR; this leads to deficiency of GSH in the epithelial lining fluid of the lung, as well as in other compartments, including immune system cells and the gastrointestinal tract. This deficiency is exaggerated over time as the higher-than-normal oxidant burden of cystic fibrosis leads to successively larger decrements in GSH without the normal opportunity to fully recover physiologic levels. This GSH system dysfunction may be the trigger for initial depletion of other antioxidants and may also play a role in initiating the over-inflammation characteristic of cystic fibrosis. Proper GSH system functioning also affects immune system competence and mucus viscosity, both of relevance to cystic fibrosis pathophysiology. In a way, cystic fibrosis may be thought of as the first identified disease with GSH system dysfunction.This overview provides a review of the most pertinent recent research findings in this area. Exogenous augmentation of GSH in the lung epithelial lining fluid is possible, and therapeutic approaches include administration of aerosolized buffered GSH, intravenous GSH, and oral GSH. However, it is important to remember that the pathophysiology of cystic fibrosis is multifactorial, and rectification of GSH system dysfunction in patients with cystic fibrosis will not eliminate all harmful effects of the disease. The promising results of two clinical trials of aerosolized buffered GSH in cystic fibrosis patients have been published or accepted for publication at the time of this writing. GSH depletion in lung epithelial lining fluid has also been noted in other respiratory diseases such as COPD, idiopathic pulmonary fibrosis, and adult respiratory distress syndrome, and therapies to augment GSH may also be contemplated in these diseases.

The role of cGMP in the regulation of rabbit airway ciliary beat frequency

The involvement of cyclic guanosine 3',5'-monophosphate (cGMP) and cGMP-dependent protein kinase (PKG) and their interaction with the Ca2+-dependent mechanisms in the regulation of ciliary activity are not well understood. To investigate how cGMP regulates ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca2+]i) of rabbit tracheal ciliated cells in response to 8-bromo-cGMP (Br-cGMP) were simultaneously quantified using digital, high-speed phase-contrast and fluorescence imaging. Br-cGMP induced a response in ciliary activity that could be separated into two parts. Firstly, Br-cGMP induced a concentration-dependent increase in the basal CBF that occurred without increasing the [Ca2+]i. This response was not affected by excessively buffering the [Ca2+]i with BAPTA but was abolished by KT5823, a PKG inhibitor. Secondly, Br-cGMP induced a series of transient increases in CBF that were superimposed on the sustained increases in CBF. These transient increases in CBF correlated with the stimulation of a series of transient increases in [Ca2+]i and were abolished by BAPTA, but were unaffected by KT5823. The magnitude of the transient increases in CBF and [Ca2+]i were not dependent on the concentration of Br-cGMP. The Ca2+-dependent changes in CBF induced by ionomycin or ATP were not affected by KT5823. From these results, we propose that cGMP increases CBF in two ways: firstly through a Ca2+-independent mechanism involving PKG, and secondly through a Ca2+-dependent mechanism following the stimulation of changes in [Ca2+]i. In addition, we suggest that the Ca2+-dependent stimulation of rabbit airway ciliary activity does not initially require PKG activation.

Rethinking cystic fibrosis pathology: the critical role of abnormal reduced glutathione (GSH) transport caused by CFTR mutation

Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed.

Substance P abolishes the facilitatory effect of ATP on spontaneous glycine release in neurons of the trigeminal nucleus pars caudalis

Glycine release was facilitated by the activation of presynaptic ATP receptors (P(2X)-type) in a preparation of dissociated trigeminal nucleus pars caudalis neurons in which the native synaptic boutons were preserved. The action of ATP was completely blocked by substance P (SP) without alteration of the miniature IPSC (mIPSC) amplitude distribution. SP itself had no effect on mIPSC frequency or amplitude. The inhibitory effect of SP on ATP action was blocked by CP99994, indicating that the SP receptors are of the neurokinin-1 type. The ATP-induced facilitation of the mIPSC frequency was unaffected by Cd(2+). Moreover, SP did not inhibit the increase in mIPSC frequency induced high K(+) application, suggesting that SP did not modulate voltage-dependent calcium channels or subsequent steps in the release process. KT5720 and phorbol 12-myristate 13-acetate did not block SP action, indicating that neither the cAMP-protein kinase A nor the protein kinase C pathway mediates the SP effects. However, in the presence of N-(6-aminohexyl)-5-chloro-1-naphthalene sulphonamide (W-7), SP was no longer able to inhibit the ATP-induced stimulation of mIPSC frequency. 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine also suppressed the SP action, suggesting that SP modulates P(2X) receptors via a Ca(2+)/calmodulin-dependent protein kinase II-mediated pathway. In conventional whole-cell mode, the presence of W-7 in the patch pipette did not affect the SP inhibitory action. Thus, SP is not likely to be generating its modulation through the production of a retrograde signal (involving calmodulin) from the postsynaptic cell to the presynaptic boutons. These results are the first demonstration of the modulation of one presynaptic receptor by another. Because SP inhibits the ATP stimulation of glycine release, SP may play a significant role in hyperalgesia or chronic pain.

Regulation of mucociliary motility by nitric oxide and expression of nitric oxide synthase in the human sinus epithelial cells

OBJECTIVES

This study was performed to investigate the changes in ciliary beat frequency (CBF) after treatment with Larginine in the human sinus mucosa and to determine the distribution of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in the healthy sinus mucosa.

STUDY DESIGN/METHODS

CBF was measured in the sphenoid sinus mucosa of 12 patients who underwent trans-septal trans-sphenoidal hypophysectomy for the treatment of pituitary gland tumor. CBF was measured over 24 hours in Dulbecco's modified Eagle's medium (DMEM) after treatment with L-arginine, its inactive spatial isomer D-arginine, or an NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). DMEM without treatment with these materials was used as a control. Other pieces of the mucosa were exposed to L-NAME and its inactive spatial isomer D-NAME after preincubation with L-arginine. The specimens were immunohistochemically stained for iNOS and eNOS.

RESULTS

CBF increased 24 hours after treatment with L-arginine as compared with control groups. CBF increased in proportion to the increasing concentrations of L-arginine. There was no significant change after treatment with D-arginine or L-NAME. CBF increased after treatment with L-arginine at 30 minutes and maintained for 24 hours. L-NAME inhibited the increase in CBF by L-arginine, but D-NAME showed no such effect. Immunoreactivity to both iNOS and eNOS was frequently observed in the ciliated epithelial cells and was stronger to eNOS than to iNOS.

CONCLUSIONS

From the results of this study it is suggested that nitric oxide (NO) produced by iNOS and eNOS using L-arginine may increase CBF in the healthy sinus mucosa and that NO may have a regulatory function in ciliary motility in the human sinus mucosa.