Effects of glucose concentration on osteogenic differentiation of type II diabetes mellitus rat bone marrow-derived mesenchymal stromal cells on a nano-scale modified titanium

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) is a common disease worldwide. Patients with DM have an increased risk of losing their teeth compared with other individuals. Dental implants are a standard of care for treating partial or full edentulism, and various implant surface treatments have recently been developed to increase dental implant stability. However, some studies have reported that DM reduces osseointegration and the success rate of dental implants. The purpose of this study was to determine the effects of high glucose levels for hard tissue formation on a nano-scale modified titanium surface.

MATERIAL AND METHODS

Titanium disks were heated at 600°C for 1 h after treatment with or without 10 m NaOH solution. All disks were incubated with type II DM rat bone marrow-derived mesenchymal stromal cells before exposure to one of four concentrations of glucose (5.5, 8.0, 12.0 or 24.0 mm). The effect of different glucose concentrations on bone marrow-derived mesenchymal stromal cell osteogenesis and inflammatory cytokines on the nano-scale modified titanium surface was evaluated.

RESULTS

Alkaline phosphatase activity decreased with increasing glucose concentration. In contrast, osteocalcin production and calcium deposition were significantly decreased at 8.0 mm glucose, but increased with glucose concentrations over 8.0 mm. Differences in calcium/phosphate ratio associated with the various glucose concentrations were similar to osteocalcin production and calcium deposition. Inflammatory cytokines were expressed at high glucose concentrations, but the nano-scale modified titanium surface inhibited the effect of high glucose concentrations.

CONCLUSION

High glucose concentration increased hard tissue formation, but the quality of the mineralized tissue decreased. Furthermore, the nano-scale modified titanium surface increased mineralized tissue formation and anti-inflammation, but the quality of hard tissue was dependent on glucose concentration.

Adenosine A3 receptor-mediated airway microvascular leakage: role of mast cells and tachykinins

To determine whether adenosine A3 receptor stimulation produces airway inflammation and, if so, what the mechanism of action is, we studied microvascular permeability in the rat trachea. After intravenous injection of Evans blue dye, adenosine and various adenosine analogues were given by inhalation, and the tracheal microvascular permeability was determined by a photometric measurement of extravasated dye. N6-2-(4-aminophenyl)-ethyladenosine (APNEA), an adenosine A3 receptor agonist, dose dependently increased plasma protein extravasation, whereas adenosine, the A1-receptor agonist N6-(R-phenylisopropyl)-adenosine, or the A2-receptor agonist 5'-N-ethyl-carboxamidoadenosine had no effect. The effect of APNEA was not altered by the adenosine A1/A2 receptor antagonist 8-(p-sulphophenyl)-theophylline, but was reduced by depletion of mast cell-derived mediators with compound 48/80 or pretreatment with the tachykinin NK1 receptor antagonist CP99,994. These results suggest that activation of A3 receptor specifically increase airway microvascular permeability probably via mast cell-derived mediators and tachykinins.

Effect of cromolyn on adenosine-induced airway microvascular leakage in sensitized rats

Inhalation of adenosine causes bronchoconstriction in asthmatic subjects, but the effect of this purine nucleotide on airway vascular permeability is unknown. In order to determine whether adenosine produces airway microvascular leakage and, if so, to examine the effect of cromolyn (sodium cromoglycate (SCG)) on this extravasation of Evans blue was measured in the airways of ovalbumin-sensitized Brown Norway rats. Inhaled adenosine caused microvascular leakage in sensitized but not in non-sensitized rats, and the response was abolished by capsaicin pretreatment or the tachykinin neurokinin-1 receptor antagonist FK888. Adenosine-induced vascular leakage became apparent in nonsensitized rats when treated with phosphoramidon, and airway neutral endopeptidase activity was lower in sensitized than in non-sensitized animals. The extravasation induced by adenosine in sensitized rats was dose dependently inhibited by SCG aerosols, SCG likewise inhibited microvascular responses to substance P, but had no effect on those to platelet-activating factor. These results suggest that: 1) adenosine induces airway microvascular leakage in sensitized rats through stimulation of neurokinin-1 receptors; 2) this effect is associated with a sensitization-induced decrease in neutral endopeptidase activity; and 3) sodium cromoglycate inhibits adenosine-induced extravasation, presumably via functional antagonism of tachykinins.

Effect of azelastine on platelet-activating factor-induced microvascular leakage in rat airways

To determine the effect of the antiallergic drug azelastine on airway mucosal inflammation, we studied airway microvascular permeability in response to platelet-activating factor (PAF) in pathogen-free rats. Vascular permeability and neutrophil accumulation were assessed by the percent area occupied by Monastral blue-labeled blood vessels and by myeloperoxidase-containing granulocytes, respectively, in whole mounts of the trachea and main bronchus. Intravenous PAF caused dose-dependent increases in the area density of Monastral blue-labeled vessels and neutrophil influx, and the former effect was inhibited by depletion of circulating neutrophils by cyclophosphamide or treatment with the neutrophil elastase inhibitor ONO-5046. Pretreatment with azelastine inhibited PAF-induced vascular leakage without affecting neutrophil accumulation. This inhibitory effect of azelastine was not seen in neutropenic rats and ONO-5046-treated rats. PAF increased neutrophil elastase contents in bronchoalveolar lavage fluid, an effect that was inhibited by azelastine. Therefore, azelastine attenuates PAF-induced airway mucosal microvascular leakage, probably involving inhibition of the release of neutrophil elastase from activated neutrophils.

[Effect of heparin on airway goblet cell secretion in sensitized guinea pigs]

Heparin and related proteoglycans are released from mast cells and possess anti-inflammatory and anti-complement activities. To elucidate whether heparin affects goblet cell secretion in asthmatic airways and, if so, what the mechanism of action is, we studied guinea pigs sensitized with ovalbumin (OVA) by determining the mucus score (MS) of tracheal goblet cells stained with Alcian blue and PAS. Inhalation of OVA caused a rapid decrease in MS in a dose-dependent manner, with the maximal decrease being from 545 +/- 26 to 192 +/- 35 (p < 0.001), indicating an increase in goblet cell mucus discharge. This effect was selectively inhibited by the histamine H2 receptor blockade with cimetidine. Prior inhalation of heparin inhibited OVA-induced goblet cell secretion in a dose-dependent fashion, but had no effect on histamine-induced goblet cell secretion. The OVA-induced histamine release from the tracheal tissue was likewise inhibited by heparin. These results suggest that allergic challenge stimulates airway goblet cell secretion mainly through the release of histamine and the concomitant activation of histamine H2 receptors on goblet cells, and that heparin protects against this effect by inhibiting the histamine release from mast cells.

Synthesis and antiallergic activity of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonate derivatives

The derivatives of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonates were synthesized and evaluated for antiallergic activity. The 2,3-dihydroxyethoxy group was introduced to the phenyl ring from the standpoint of lipophilicity and electronic effects of substituent. The IgE-induced rat passive cutaneous anaphylaxis (PCA) was inhibited by oral administration of several substituted 2-[(4-propoxyphenyl)carbamoyl]ethyldimethylsulfonium p-toluenesulfonate derivatives. Among them (+/-)-2-[N-[4-(3-ethoxy-2-hydroxypropoxy)phenyl]carbamoyl]ethyldimeth ylsulfonium p-toluenesulfonate (1a, IPD-1151T) was found to possess considerable activity in the PCA test, and it was launched as Suplatast tosilate in Japan.

A human bronchial epithelial cell line releases arginine vasopressin: involvement of Ca2+ -activated K+ channels

To determine whether airway epithelium releases arginine vasopressin (AVP) and, if so, what the mechanism of the release is, we studied cultured human bronchial epithelial cell line, 16-HBE cells, in vitro. The cells spontaneously released small but significant amounts of AVP, and this release was dose dependently increased by platelet-activating factor (PAF) or bradykinin (BK). The PAF- and BK-induced AVP release was inhibited by 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate, a phospholipase C inhibitor, and thapsigargin but not by Ca2+ -free solution. Pretreatment with the big conductance Ca2+-activated K+ channel blocker iberiotoxin attenuated the stimulated release of AVP, whereas apamin and glibenclamide were without effect. These results suggest that human bronchial epithelial cells release AVP and that the release may be stimulated by phospholipase C activation, mobilization of Ca2+ from internal stores and the concomitant activation of big conductance Ca2+-activated K+ channels.

[Effect of adenosine and its analogues on microvascular leakage in the rat trachea]

We examined the effects of adenosine and its analogues on vascular permeability in rat trachea using Evans blue dye as a marker for plasma leakage. Inhalation of N6-2-(4-aminophenyl) ethyladenosine (APNEA), a specific A 3 receptor agonist, increased microvascular leakage in a dose-dependent manner, but adenosine, [R]-N6-(1-Methyl-2-phenylethyl) adenosine (R-PIA), aspecific A 1 receptor agonist, and 5'-(N-ethyl-carboxamide) adenosine (NECA), a specific A 2 receptor agonist, had no effect. Inhalation of capsaicin increased vascular permeability in a dose-dependent manner. Pretreatment with NECA (10-1000 nmol/kg, i.v.) but not adenosine (100 nmol/kg i.v.), R-PIA (100 nmol/kg, i.v.) or APNEA (100 nmol/kg, i.v.) inhibited microvascular leakage produced by capsaicin aerosol (3 x 10(-5) M) in a dose-dependent manner. However, NECA (10-100 nmol/kg, i.v.) failed to inhibit substance P aerosol (10(-4) M)-induced extravasation of the dye. These findings suggest that stimulation of adenosine A 3 receptors produces airway vascular permeability, and that A 2 receptors inhibit neurogenic plasma extravasation, presumably by inhibiting the release of tachykinins from sensory nerves.

[A case of pulmonary eosinophilic granuloma undergoing spontaneous remission]

A case of pulmonary eosinophilic granuloma that underwent spontaneous remission is presented. A 23-year old man presented with dry cough and fever. Chest X-ray film revealed diffuse reticulo-nodular infiltrates in the middle and upper lung fields. Chest CT and HRCT showed multiple cystic lesions with thick walls and small nodules predominantly in the inner zone. Based on radiographic findings, pulmonary eosinophilic granuloma was suspected. Bronchoalveolar lavage cell data showed lymphocyte and eosinophil alveolitis with no increase of CD 1 lymphocytes. The symptoms and radiographic findings improved markedly within 4 months after the onset of symptoms without treatment and upon cessation of smoking. Chest CT and HRCT showed that the cystic walls were thinner and that the small nodules had decreased. Thoracoscopic lung biopsy revealed granulomatous lesions consisting of CD 1 and S-100 protein positive histiocytes with infiltration of eosinophils and fibrous lesions. Pulmonary eosinophilic granuloma was diagnosed. There has been no recurrence for 1 year.

Inhaled cromoglycate reduces airway neurogenic inflammation via tachykinin antagonism

To determine whether sodium cromoglycate (SCG) inhibits airway neurogenic inflammation and, if so, to elucidate the mechanism of its action, we studied plasma extravasation evoked by hypertonic saline in the rat trachea by measuring the amount of extravasated Evans blue dye. Inhalation of hypertonic saline (5-15% NaCl) produced microvascular leakage, an effect that was reduced by pretreatment with SCG in a dose-dependent manner. Inhaled SCG (10 mg/ml) for 2 min did not affect the basal vascular permeability, but significantly inhibited the 10% NaCl-induced plasma extravasation by 34%. SCG likewise inhibited the responses of microvascular leakage to substance P aerosols, whereas it was without effect on those to platelet activating factor aerosols. These results suggest that SCG inhibits airway neurogenic inflammation presumably via functional antagonism of tachykinins, and that this novel effect may be involved in the therapeutic efficacy of SCG in the treatment of airway inflammatory diseases including asthma.

[A case of chronic necrotizing pulmonary aspergillosis successfully treated with combination therapy of antifungal drugs and ulinastatin]

A 64-year-old woman with a history of old tuberculosis, had a fungus ball shadow with meniscus sign in the upper right lung field on a chest X-ray film in 1991. Based on the chest X-ray findings, pulmonary aspergilloma was suspected. Because the size of the intracavitary fungus ball increased, the patient was treated with itraconazole over one year in 1995, but there was no improvement. One month later, she was admitted because of fever, hemoptysis and productive cough, and chest X-ray showed an enlargement of intracavitary mass and infiltrative shadow in the right lung. Chronic necrotizing aspergillosis was diagnosed on the basis of her clinical and radiographic features, and positive serological test. Although itraconazol and amphotericin B were given, cavity and intracavitary fungus ball shadow kept growing. Combination therapy of antifungal drugs and ulinastatin markedly improved symptoms and resulted in complete disappearance of the fungus ball on chest CT scan.

[Role of neutrophil elastase in allergen-induced airway microvascular leakage in sensitized guinea pigs]

To determine the role of neutrophil elastase in allergen-induced airway microvascular leakage, we assessed vascular permeability of guinea pig trachea by measuring the extravasation of Evans blue dye in the circulating blood. Inhalation of ovalbumin (OA) to guinea pigs sensitized with OA caused Evans blue extravasation, indicating an increased microvascular permeability. Pretreatment with ONO-5046 a specific inhibitor of neutrophil elastase, inhibited OA-induced vascular leakage in a dose-dependent manner. Tracheal instillation of human neutrophil elastase likewise increased microvascular permeability, and this effect was almost completely abolished by ONO-5046. Challenge with OA increased the number of neutrophils and neutrophil elastase activity in the bronchoalveolar lavage fluid, and these effects were inhibited by ONO-5046. These results suggest that neutrophil accumulation into the airway and the subsequent release of neutrophil elastase may play a role in the airway microvascular leakage produced by antigen challenge.

Lipopolysaccharide-induced goblet cell hypersecretion in the guinea pig trachea: inhibition by macrolides

We studied the effects of macrolides on lipopolysaccharide (LPS)-induced airway goblet cell secretion in the guinea pig trachea. The goblet cell secretion was assessed in histological sections of the tracheal mucosa stained with alcian blue and periodic acid Schiff by arbitrarily determining mucus score, which is inversely related to the magnitude of mucus discharge. Inhalation of Escherichia coli LPS (5 mg/kg) caused a time-dependent decrease in mucus score, with the maximal response being from 542 +/- 49 to 92 +/- 20 arbitrary units (P < 0.001) after 3 h, which was accompanied by an increase in the number of neutrophils in the tracheal mucosa. The LPS-induced mucus discharge was inhibited by oral clarithromycin and erythromycin in a dose-dependent manner (5 and 10 mg/kg), whereas amoxicillin and cefaclor had no effect. Each dose of clarithromycin and erythromycin, but not amoxicillin or cefaclor, likewise attenuated the LPS-induced recruitment of neutrophils. These results suggest that LPS stimulates goblet cell secretion and neutrophil accumulation in the airways and that macrolides may be of value in protecting against neutrophil-associated airway hypersecretion.

[Six patients with pneumonitis related to blended Chinese traditional medicines]

We encountered six patients with pneumonitis related to blended chinese traditional medicine (Kampo). The duration of treatment with kampo ranged from 14 to 110 days (mean: 38 days). The most common complaints were dyspnea, fever, and dry coughing. Fine crackles were heard at the bases of both lungs. Abnormal laboratory findings included high values of C-reactive protein and glutamic-oxaloacetic transaminase in all patients, lactate dehydrogenase in 5 patients, and eosinophil count in 1 patient. Chest X-ray films and CT films revealed diffuse reticulo-nodular interstitial shadows with consolidation in both lung fields in 3 patients and pleural effusion in 1 patient. Bronchoalveolar lavage was done in 4 patients; examination of the lavage fluid showed lymphocyte alveolitis, either pure or associated with neutrophilia and eosinophilia in 3 patients. Inverted CD4/CD8 lymphocyte ratios were found in 3 patients. Transbronchial lung biopsy was done in 4 patients and specimens from 3 of those 4 showed organizing pneumonitis with thickening of alveolar septa. Lymphocyte stimulation tests were positive in 4 patients. Discontinuation of the drug (2 patients) or administration of corticosteroids (4 patients) was followed by rapid improvement. Patients being treated with kampo preparations should be observed for signs and symptoms of drug-induced pneumonitis.

[Pneumonia caused by Saiboku-to]

A 72-year-old man was being treated with Saiboku-to for throat discomfort. Forty-two days after the start of Saiboku-to therapy, dyspnea and fever developed and he was admitted to the hospital. Arterial blood gas analysis showed arterial hypoxemia, and a chest X-ray film and chest CT scan showed diffuse linear-nodular shadows in both lung fields. The results of a lymphocyte-stimulation test were positive for Saiboku-to and Saiboko-to-induced pneumonia was diagnosed. Saiboku-to was stopped and prednisolone was given. The symptoms, respiratory status and chest X-ray findings markedly improved. To our knowledge, this is the fifth case of Saiboku-to-induced pneumonia reported in Japan.

[Cavitary lung cancer with a fungus ball-like shadow]

A 75-year-old woman had an irregularly shaped cavitary lesion in the right upper lung field on a chest X-ray film and a CT scan. Primary lung cancer was suspected, but no evidence of malignancy or of infection was found on examination of specimens obtained by transbronchial biopsy and by lavage. Seven months after the first examination the cavity was found to have enlarged and an intra-cavitary fungus ball like shadow was seen. On the basis of these findings, pulmonary aspergilloma with or without primary lung cancer was suspected. Examination of a specimen obtained by transbronchial biopsy revealed squamous cell carcinoma. Right upper lobectomy was done, and the resected tissue included a polypoid nodule and a cavity wall composed of a milky-white solid tumor. Microscopic examination revealed a moderately differentiated squamous cell carcinoma in both the cavity wall and the polypoid nodule, and no evidence of fungal involvement.

[Effect of sodium cromoglycate on airway vascular leakage caused by hypertonic saline in the rat trachea]

The action of the anti-asthmatic drug sodium cromoglycate (SCG) on airway inflammation remains uncertain. Using Evans blue dye as a maker of plasma leakage, we studied the effect of SCG on neurogenic vascular extravasation evoked by hypertonic saline (HTS) in the rat trachea. Inhalation of HTS (5-15%) caused a concentration-dependent increase in plasma leakage, but inhaled 0.9% NaCl had no effect. Inhalation of SCG did not affect the baseline level of vascular permeability, but it inhibited the effect of HTS in a dose-dependent manner: plasma extravasation induced by 10% NaCl was significantly reduced by 2 minutes of inhalation of SCG at concentrations of 10 and 50 mg/ml (p < 0.05 and p < 0.01, respectively). SCG (10 mg/ml), also inhibited the changes in microvascular permeability caused by aerosols of substance P (10(-4) M), whereas it did not affect the responses to aerosols of platelet-activating factor (3 x 10(-4) M). A similar dose of SCG did not significantly alter microvascular leakage caused by 5% NaCl. However, phosphoramidon, a selective inhibitor of neutral endopeptidase, potentiated the response to 5% NaCl, an effect that was inhibited by SCG (p < 0.05). These results suggest that SCG inhibits HTS-induced airway vascular permeability, presumably through a tachykinin-antagonist-like property, and that this inhibition is exaggerated when the activity of endogenous neutral endopeptidase is low.

Hypoxia impairs nitrovasodilator-induced pulmonary vasodilation: role of Na-K-ATPase activity

To elucidate the effect of hypoxia on nitrovasodilator-induced pulmonary vasodilation, we studied canine pulmonary arterial rings under isometric conditions in vitro. Exposure to hypoxia inhibited the relaxant responses of KCl-contracted tissues to sodium nitroprusside (SNP), so that the maximal relaxation (Emax) and the negative logarithm of molar concentration required to produce 50% relaxation (pD2) were decreased from 92 +/- 7 to 62 +/- 5% and from 5.8 +/- 0.2 to 4.7 +/- 0.3, respectively (means +/- SE, P < 0.01 for each). This effect was likewise observed when 8-bromoguanosine-3',5'-cyclic monophosphate was used as a relaxant. The impairment of SNP-induced relaxation of endothelium-denuded rings under hypoxia was abolished by ouabain or K(+)-free solution. Incubation with SNPincreased intracellular cGMP contents in a dose dependent manner, an effect that was not altered by hypoxia. SNP also increased ouabain-sensitive 86Rb uptake, and this effect was inhibited by hypoxia. These results suggest that hypoxia reduces nitrovasodilator-induced relaxation of pulmonary artery, probably through an inhibition of cGMP-dependent sarcolemmal Na-K-adenosine triphosphatase activity.

[T-kinin-induced increase in airway vascular permeability and its modulation by angiotensin-converting enzyme]

We studied the effect of T-kinin on airway vascular permeability and its modulation by endogenous peptidases in anesthetized rats in vivo, Vascular permeability was assessed by photometric measurement of extravasated Evans blue dye after formamide extraction. Intravenous injection of T-kinin increased dye extravasation in the trachea and main bronchi in a dose-dependent manner. Plasma extravasation evoked by T-kinin was inhibited by Hoe 140, a B2 receptor but-not by des Arg9-Leu8-bradykinin, a B1 receptor antagonist. Treatment with captopril, an angiotensin-converting enzyme inhibitor, potentiated the T-kinin-induced plasma extravasation, whereas phosphoramidon, a neutral endopeptidase inhibitor, had no effect. These results suggest that T-kinin increases airway vascular permeability via stimulation of B2 receptors, and that this effect is modulated by endogenous angiotensin-converting enzyme.

Lipoxin A4 inhibits cholinergic neurotransmission through nitric oxide generation in the rabbit trachea

The effect of lipoxin A4 and lipoxin B4 on cholinergic neurotransmission in rabbit tracheal segments was studied under isometric conditions in vitro. Lipoxin A4 attenuated the contractile responses to electrical field stimulation and caused a rightward shift of the frequency-response curves, so that the stimulus frequency required to produce a half-maximal effect (ES50) increased from 8.1 +/- 0.8 to 25.7 +/- 1.9 Hz (P < 0.001), whereas lipoxin B4 had no effect. In contrast, lipoxin A4 did not alter the contractile responses to acetylcholine. Pretreatment of tissues with NG-nitro-L-arginine methylester inhibited the effect of lipoxin A4 on electrical field stimulation, but NG-nitro-D-arginine methylester did not. This inhibition by NG-nitro-L-arginine methylester was reversed by L-arginine but not by D-arginine. These results suggest that lipoxin A4 prejunctionally reduces the vagal nerve-mediated contraction of airway smooth muscle, probably by inhibiting the release of acetylcholine, and that this effect may be exerted through stimulation of nitric oxide generation.

Cyclic adenosine monophosphate-mediated release of nitric oxide from canine cultured tracheal epithelium

Nitric oxide (NO) may play a part in pulmonary vascular regulation and bronchomotor control and has been detected in exhaled air. We report the release of NO from airway epithelial cells and its regulation by cyclic adenosine monophosphate (cAMP). To directly measure NO release, a highly specific amperometric sensor for NO made of Pt/Ir alloy coated with a three-layered membrane consisting of KCI, NO-selective resin, and normal silicon resin was developed. Immersion of this sensor in the medium containing canine cultured tracheal epithelium detected baseline levels of NO at 9.6 +/- 1.6 nM (mean +/- SE), which was reduced by NG-nitro-L-arginine methylester (L-NAME) but not by D-NAME. This inhibition was reversed by L-arginine. Addition of isoproterenol, 3-isobutyl-1-methylxanthine, and forskolin caused a rapid increase in NO, an effect that was not altered by Ca(2+)-free medium in the presence of the intracellular Ca2+ chelator BAPTA-AM and the calmodulin antagonist W-7. Bradykinin, ionomycin, and ATP were without effect on NO release. The forskolin-induced NO release was accompanied by intracellular accumulation of cAMP and Ca2+. In contrast, bradykinin increased intracellular Ca2+ but not cAMP levels. Cytochemistry of cultured tracheal epithelium showed a positive staining with NADPH diaphorase activity. These results suggest that airway epithelial cells spontaneously release NO and that the release may be stimulated specifically through cAMP-dependent mechanism.

Effect of T-kinin on microvascular permeability and its modulation by peptidases in rat airways

T-kinin (Ile-Ser-bradykinin), the product of T-kininogen, has been found in rat plasma during systemic inflammation, but the effect of this kinin on airway inflammatory response is unknown. We examined the effect of T-kinin on vascular permeability in airways of anesthetized rats in vivo by using photometric measurement of the extravasated Evans blue. Intravenous injection of T-kinin (0.1-10 mumol/kg) increased dye extravasation in a dose-dependent manner, with 134% for trachea and 117% for bronchi by 1 mumol/kg. Pretreatment with bradykinin B2-receptor antagonist Hoe-140 (100 nmol/kg), but not the B1-receptor antagonist des-Arg9-Leu8-bradykinin (5 mg/kg), abolished plasma extravasation evoked by T-kinin (1 mumol/kg). NK1 tachykinin-receptor antagonist CP-99994 (4 mg/kg) did not affect T-kinin-induced vascular leakage. Pretreatment with captopril (2.5 mg/kg), angiotensin-converting enzyme inhibitor, potentiated T-kinin (100 nmol/kg)-induced plasma extravasation, whereas phosphoramidon (2.5 mg/kg), a neutral endopeptidase inhibitor, had no effect. We conclude that T-kinin produces airway vascular extravasation via stimulation of B2 receptors. The effect is modulated by endogenous angiotensin-converting enzyme and is not mediated via activation of sensory nerve.

Regulation of airway cholinergic neurotransmission by Ca(2+)-activated K+ channel and Na(+)-K+ adenosinetriphosphatase

Stimulation of Ca(2+)-activated K+ channel and Na(+)-K(+)-ATPase may play an important role in the relaxant responses of airway smooth muscle to certain bronchodilators. To test whether cholinergic neuroeffector transmission can be modulated by Ca(2+)-activated K+ channel and Na(+)-K(+)-ATPase, canine airway smooth muscle was studied under isometric conditions in vitro. Addition of charybdotoxin (10(-7) M) did not alter the contractile responses to acetylcholine but augmented electrical field stimulation-induced contractions at 1-10 Hz (p < .01), whereas apamin and glibenclamide were without effect. This effect of charybdotoxin was dose dependent, with the maximal increase being 36.8 +/- 5.3% (p < .001). Ouabain (10(-7) M) increased contractions induced by both electrical field stimulation and acetylcholine. The magnitude of the increase in contractile responses to electrical field stimulation was similar to that of acetylcholine at an ouabain concentration of up to 3 x 10(-7) M, but the former was significantly greater at 10(-6) M ouabain (p < .05). These results suggest that both Ca(2+)-activated K+ channel and Na(+)-K(+)-ATPase may be operative in the regulation of cholinergic neurotransmission by inhibiting the exocytotic release of acetylcholine from the vagal nerve terminals.

Viral infection potentiates the increase in airway blood flow produced by substance P

We examined the effect of respiratory tract infection with Sendai virus on the responsiveness of airway blood flow to substance P (SP) in rats. Pathogen-free rats were inoculated with either Sendai virus suspension or sterile viral growth medium into each nostril. Five days later, we measured airway and esophageal blood flows before and immediately after injection of SP or histamine into the left ventricle of rats in both groups using a modification of the reference-sample microsphere technique. Viral infection potentiated the increase in airway blood flow evoked by SP but not by histamine. We also examined the effect of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) on the SP-induced increase in airway blood flow. Both phosphoramidon (NEP inhibitor) and captopril (ACE inhibitor) potentiated the increase in airway blood flow produced by SP in pathogen-free rats. In the presence of both peptidase inhibitors, a submaximal dose of SP increased blood flow to a similar level in infected and pathogen-free rats. Thus decreased activity of both ACE and NEP may be involved in the exaggerated increase in airway blood flow evoked by SP in virus-infected rats.

Effect of azelastine on airway hyperresponsiveness mediated by stimulated macrophages

The effect of the anti-allergic drug azelastine, 4-(p-chlorobenzyl)-2-(hexahydro-1-methyl-1H-azepine-4-yl)-1-(2H)-phth alazione), on airway hyperresponsiveness induced by immunologically stimulated pulmonary alveolar macrophages was investigated in canine bronchial segments under isometric conditions in vitro. Macrophages stimulated with anti-dinitrophenyl immunoglobulin E (IgE) antibody and dinitrophenyl-human serum albumin potentiated the contractile responses to electrical field stimulation at all frequencies, an effect that was abolished by azelastine (3 x 10(-5) M). In contrast, azelastine had no effect on the potentiation of the contractile responses to electrical stimulation by U46619, a thromboxane A2 mimetic. The IgE-mediated release of thromboxane A2 from macrophages was inhibited by azelastine in a concentration-dependent fashion, the maximal decrease and the concentration required to produce a half-maximal effect being 84 +/- 6% (P < 0.001) and 16 microM, respectively. These results suggest that azelastine may attenuate macrophage-induced parasympathetic airway hyperresponsiveness through an inhibition of the release of thromboxane A2.

Effect of erythromycin on endotoxin-induced microvascular leakage in the rat trachea and lungs

To determine whether the macrolide antibiotic erythromycin prevents microvascular leakage produced by lipopolysaccharide (LPS), we studied tracheae and lungs of pathogen-free rats. Tracheal vascular permeability and neutrophil recruitment were assessed by the percent area occupied by Monastral blue-labeled blood vessels and by myeloperoxidase-containing granulocytes, respectively, in tracheal whole mounts. Pulmonary microvascular leakage was evaluated by lung wet-to-dry (W/D) weight ratio. Inhalation of Escherichia coli LPS (5 mg/kg) caused time-dependent increases in tracheal vascular permeability, neutrophil influx, and lung W/D ratio. These responses were inhibited by pretreatment with oral erythromycin, but not by ampicillin or cefaclor, in a dose-dependent manner: erythromycin at 10 mg/kg daily for 1 wk reduced the area density of Monastral blue-labeled vessels from 6.7 +/- 1.2 to 1.4 +/- 0.3% (p < 0.01), the number of neutrophils (from 365 +/- 51 to 149 +/- 30 cells/mm2, p < 0.01), and lung W/D weight ratio (from 6.76 +/- 0.30 to 5.39 +/- 0.21, p < 0.01). This inhibitory effect of erythromycin was abolished by depletion of circulating neutrophils with cyclophosphamide. These results suggest that LPS causes acute lung injury, microvascular leakage, and neutrophil recruitment in the trachea, and that erythromycin protects against these changes, probably by acting on neutrophils.

Plasma extravasation in the rat trachea induced by cold air is mediated by tachykinin release from sensory nerves

Cold air was delivered to anesthetized, artificially ventilated, pathogen-free F344 rats via a tracheal cannula. Inhalation of cold air increased Evans blue dye extravasation in the trachea in a time-dependent (1 to 10 min) manner. Plasma extravasation increased after 3 min exposure to cold air and reached a maximum after 10 min exposure. The neutral endopeptidase inhibitor, phosphoramidon (2.5 mg/kg, intravenously), increased by 84% the plasma extravasation induced by inhalation of cold air for 1 min. The plasma extravasation evoked by 5 min exposure to cold air was abolished by the NK1 tachykinin receptor antagonist, CP-99,994 (4 mg/kg, intravenously); was reduced 30% by the B2 bradykinin receptor antagonist, HOE140 (0.1 mumol/kg, intravenously); and was not affected by H1 (pyrilamine, 10 mg/kg, intraperitoneally) or H2 (cimetidine, 10 mg/kg, intraperitoneally) histamine receptor antagonists or the cyclooxygenase inhibitor indomethacin (5 mg/kg, intravenously). In rats infected with Sendai virus, plasma extravasation evoked by inhalation of cold air was greater than in pathogen-free rats. Pretreatment with CP-99,994 (4 mg/kg, intravenously) inhibited completely the plasma extravasation induced by cold air in virus-infected rats. These findings indicate that cold air increases plasma extravasation in the rat trachea by a neurogenic mechanism that involves the release of tachykinins from sensory nerves. Kinin release may also play a role in this neurogenic inflammatory response.

Synthesis and biological activity of the metabolites of syn-3-ethyl-7-methyl-3,7-diazabicyclo[3.3.1]non-9-yl 4-chlorobenzoate hydrochloride

Five metabolites of syn-3-ethyl-7-methyl-3,7-diazabicyclo[3.3.1]non-9-yl 4-chlorobenzoate hydrochloride (YUTAC) (1) were prepared and examined for Na+ current blocking activity in guinea pig ventricular myocytes. These metabolites showed lower inhibitory activities than the parent compound or were inactive.

Tachykinins and kinins in antigen-evoked plasma extravasation in guinea-pig nasal mucosa

The plasma extravasation evoked by instillation of 5% ovalbumin in the nasal mucosa of sensitized guinea-pigs was potentiated by the neutral endopeptidase inhibitor, phosphoramidon, and was reduced by the tachykinin NK1 receptor antagonist, CP-96,345. The bradykinin B2 receptor antagonist, HOE 140, also reduced the plasma extravasation evoked by the antigen. The combination of HOE 140 and CP-96,345 did not increase further the inhibition caused by HOE 140 alone. Plasma extravasation evoked by instillation of capsaicin was abolished by CP-96,345. HOE 140 blocked and CP-96,345 markedly reduced plasma extravasation caused by instillation of bradykinin. Plasma extravasation evoked by instillation of substance P was not affected by HOE 140. We conclude that antigen challenge causes plasma extravasation in the nasal mucosa of sensitized guinea-pigs, an effect that is due in part to the release of tachykinins from sensory nerve endings. Our evidence suggests that tachykinin release in response to antigen is provoked mainly by the release of kinins.

Piperazinealkanol ester derivatives of indomethacin as dual inhibitors of 5-lipoxygenase and cyclooxygenase

Piperazinealkanol ester derivatives of indomethacin were prepared and tested for inhibitory activities against 5-lipoxygenase (5-LO) and cyclooxygenase (CO). They inhibited 5-hydroxyeicosatetraenoic acid (5-HETE) formation by the cytosol of guinea pig polymorphonuclear leukocytes and thromboxane B2 (TXB2) formation by washed rabbit platelet suspension. Of the test compounds, 2-[4-(2-hydroxyethyl)-1-piperazinyl]-1-phenylethyl 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-3-indolylacetate dimaleate (II-8) was found to be the most active dual inhibitor of 5-LO and CO, and its inhibitory potency was higher than that of 2-[4-(3-hydroxypropyl)-1-piperazinyl]-ethyl [1-(4-chlorobenzoyl)-5-methoxy-2-methyl]-3-indolyacetate (CR-1015) (I), the lead compound.

Airway vasodilation by bradykinin is mediated via B2 receptors and modulated by peptidase inhibitors

We studied the effect of exogenous bradykinin on blood flow in the airway microcirculation of anesthetized F344 rats in vivo. We made three successive determinations of airway blood flow and cardiac output using a modification of the reference sample microsphere technique. Injection of bradykinin into the left ventricle increased airway blood flow in a dose-related manner. Pretreatment with the bradykinin B2 receptor antagonist, Hoe 140, completely abolished bradykinin-, but not histamine-induced vasodilation. A bradykinin B1 receptor agonist, [des-Arg9]bradykinin, did not affect airway blood flow. We also studied the effect of inhibitors of angiotensin-converting enzyme (captopril) and neutral endopeptidase (phosphoramidon) on bradykinin-induced vasodilation. Pretreatment with captopril, but not phosphoramidon, potentiated the bradykinin-induced vasodilation. However, the addition of phosphoramidon further potentiated the effect of captopril. We conclude that injection of bradykinin into the left ventricle produces a dose-related vasodilation in the airway microcirculation mediated via B2 receptors, an effect that is modulated primarily by angiotensin-converting enzyme and, to a lesser extent, by neutral endopeptidase.

Role of K+ channel opening and Na(+)-K+ ATPase activity in airway relaxation induced by salbutamol

To determine the role of K+ channel opening and Na(+)-K+ ATPase activity in the beta-adrenoceptor-mediated relaxation of airway smooth muscle, we studied canine bronchial segments under isometric conditions in vitro. Relaxant responses to salbutamol were not altered by glibenclamide or apamin but inhibited by charybdotoxin, where significant inhibition was observed only at salbutamol concentrations of less than 10(-6) M. In contrast, only the relaxations induced by salbutamol at 3 x 10(-6) M and greater were sensitive to ouabain. Relaxations produced by low and high concentrations of salbutamol were selectively attenuated by charybdotoxin and ouabain, respectively, in a concentration-dependent manner. These results suggest that both Ca(2+)-activated K+ channel and Na(+)-K+ ATPase may be operative in the airway relaxation induced by low and high concentrations of the beta-adrenergic agonist, respectively.

Interleukin-1 beta inhibits airway smooth muscle contraction via epithelium-dependent mechanism

To determine whether the cytokine interleukin (IL)-1 beta directly affects airway smooth muscle functions and, if so, what the mechanism of action is, we studied canine isolated bronchial segments under isometric conditions in vitro. Incubation of tissues with human recombinant IL-1 beta (10 ng/ml) for 150 min decreased the contractile responses to acetylcholine, histamine, and KCl. The inhibitory effect of IL-1 beta on the acetylcholine (10(-3) M)-induced contraction was concentration-dependent, the maximal decrease from the baseline contraction being 52 +/- 8% (mean +/- SD, p < 0.001) observed with 10 ng/ml IL-1 beta. Intracellular levels of cyclic AMP and cyclic GMP were not significantly altered by IL-1 beta. The IL-1 beta-induced inhibition of the contractile responses was not affected by pretreatment of tissues with indomethacin or propranolol, but it was greatly attenuated by mechanical removal of epithelium. These results suggest that IL-1 beta may play a protective role against bronchoconstrictor responses via epithelium-dependent mechanism such as the release of epithelium-derived relaxing factor.

Role of kinins in the vascular extravasation evoked by antigen and mediated by tachykinins in guinea pig trachea

Tachykinins released from sensory nerves mediate, at least in part, the plasma extravasation induced by allergen challenge to the airways of sensitized guinea pigs. We investigated the role of kinins in this activation of sensory nerves. We found that the increase in Evans blue dye extravasation evoked by aerosol of bradykinin (100 microM, 2 min) in the presence of phosphoramidon (2.5 mg/kg, i.v.) was abolished completely by the selective B2 bradykinin antagonist, HOE 140 (0.1 mumol/kg, i.v.), and was inhibited (60%) by the selective NK1 tachykinin receptor antagonist, CP-96,345 (2 mumol/kg, i.v.). Plasma extravasation evoked by aerosolized substance P (10 microM/kg, 2 min) in presence of phosphoramidon was abolished by CP-96,345, but was not affected by HOE 140. The extravasation of the Evans blue dye evoked by OVA (5%, 2 min) in sensitized guinea pigs was reduced by HOE 140 (45%) when the animals were perfused after 5 min and by 39% when perfusion was performed at 10 min. In the presence of phosphoramidon, the response to OVA at 10 min was reduced by 57% by HOE 140 and by 72% by CP-96,345. The combination of CP-96,345 and HOE 140 did not further increase the inhibition obtained with CP-96,345 alone. The results provide evidence that the activation of sensory nerves that contribute to Ag-evoked plasma extravasation is due to kinin release. The contribution of this cascade of events may be exaggerated in pathophysiologic conditions in which neutral endopeptidase is down-regulated.

Role of kinins in the vascular extravasation evoked by antigen and mediated by tachykinins in guinea pig trachea

Tachykinins released from sensory nerves mediate, at least in part, the plasma extravasation induced by allergen challenge to the airways of sensitized guinea pigs. We investigated the role of kinins in this activation of sensory nerves. We found that the increase in Evans blue dye extravasation evoked by aerosol of bradykinin (100 microM, 2 min) in the presence of phosphoramidon (2.5 mg/kg, i.v.) was abolished completely by the selective B2 bradykinin antagonist, HOE 140 (0.1 mumol/kg, i.v.), and was inhibited (60%) by the selective NK1 tachykinin receptor antagonist, CP-96,345 (2 mumol/kg, i.v.). Plasma extravasation evoked by aerosolized substance P (10 microM/kg, 2 min) in presence of phosphoramidon was abolished by CP-96,345, but was not affected by HOE 140. The extravasation of the Evans blue dye evoked by OVA (5%, 2 min) in sensitized guinea pigs was reduced by HOE 140 (45%) when the animals were perfused after 5 min and by 39% when perfusion was performed at 10 min. In the presence of phosphoramidon, the response to OVA at 10 min was reduced by 57% by HOE 140 and by 72% by CP-96,345. The combination of CP-96,345 and HOE 140 did not further increase the inhibition obtained with CP-96,345 alone. The results provide evidence that the activation of sensory nerves that contribute to Ag-evoked plasma extravasation is due to kinin release. The contribution of this cascade of events may be exaggerated in pathophysiologic conditions in which neutral endopeptidase is down-regulated.

Levodropropizine reduces capsaicin- and substance P-induced plasma extravasation in the rat trachea

We investigated the effect of the non-opioid, peripherally acting antitussive agent levodropropizine to reduce neurogenic plasma extravasation in the rat trachea. Levodropropizine (10, 50 and 200 mg/kg) reduced in a dose-dependent manner the extravasation of Evans blue dye evoked by capsaicin. Levodropropizine inhibited also substance P-evoked extravasation, whereas it did not affect the extravasation evoked by platelet activating factor. Levodropropizine (10 and 100 microM) did not affect the contraction produced by [Sar9,Met(O2)11]substance P, a selective agonist for tachykinin NK1 receptors, in the rat urinary bladder in vitro. These data indicate that levodropropizine inhibits capsaicin-induced plasma extravasation: (a) acting at a postjunctional level; (b) exhibiting neuropeptide selectivity and; (c) via a mechanism independent of tachykinin NK1 receptor blockade. Irrespective of the mechanism, this novel antiinflammatory action of levodropropizine underlines its potential role in inflammatory airway diseases such as bronchial asthma.

Effect of somatostatin on contractile and relaxant responses of tracheal smooth muscle in rabbits

To determine the effect of somatostatin (SRIF) on airway smooth muscle contractile and relaxant responses and its mechanism of action, we studied rabbit tracheal smooth muscle under isometric conditions in vitro. SRIF did not change the contractile responses to electrical field stimulation and acetylcholine, but it inhibited the relaxant responses to isoproterenol in a concentration-dependent manner, an effect that was reversed by treatment of tissues with pertussis toxin (PTX). In contrast, the forskolin- and verapamil-induced relaxations were not altered by SRIF. SRIF also attenuated the increase in intracellular cyclic AMP levels in response to isoproterenol. These results suggest that SRIF may decrease beta-adrenoceptor-mediated muscle relaxation by acting at the site proximal to cyclic AMP synthesis, especially at PTX-sensitive GTP-binding regulatory protein, Gi, coupled to adenylate cyclase.

Ruthenium red, but not capsazepine reduces plasma extravasation by cigarette smoke in rat airways

1. Cigarette smoke increases vascular permeability in rat airways by activating release of tachykinin from capsaicin-sensitive sensory nerves. However, the mechanism by which cigarette smoke induces secretion of sensory neuropeptides is unknown. Here we hypothesized that cigarette smoke activates sensory nerve endings via a mechanism similar to that of capsaicin. 2. We studied the effects of ruthenium red, an inorganic dye which blocks the cation influx promoted by capsaicin and of the capsaicin antagonist capsazepine on the increase in vascular permeability produced by cigarette smoke, capsaicin, hypertonic saline and substance P in the trachea of pentobarbitone anaesthetized rats. We also investigated the ability of cigarette smoke to desensitize sensory nerve fibres. 3. Ruthenium red (10 mM) by aerosol blocked the increase in vascular permeability induced by capsaicin (0.5 microM) and reduced the response to cigarette smoke (5 puffs) but did not affect responses evoked by hypertonic saline (7.2%) or by substance P (10 microM) (all given by aerosol). Aerosols of capsazepine (0.1 mM) prevented extravasation by capsaicin, but did not inhibit response to cigarette smoke, hypertonic saline or substance P. Finally, pre-exposure to a high dose of cigarette smoke (10 puffs) prevented the extravasation caused by cigarette smoke (5 puffs) itself and by intravenous capsaicin (150 micrograms kg-1), but not that by intravenous substance P (10 nmol kg-1). 4. The present results show that cigarette smoke: (a) increases vascular permeability in the rat airways by a mechanism that is not antagonized by capsazepine, and is partially sensitive to rutheniun red; (b)produces desensitization of capsaicin-sensitive sensory nerves. We propose that chemical(s) contained in or agent(s) produced by cigarette smoke in the airways share partially a common pathway with capsaicin to activate peptide release from capsaicin-sensitive sensory nerves, but do not bind to the putative 'capsaicin receptor'.

Role of neurogenic inflammation in antigen-induced vascular extravasation in guinea pig trachea

Conflicting results have been reported about the role of sensory nerves in the allergen-induced plasma extravasation in sensitized guinea pigs using capsaicin desensitization. To investigate the role of tachykinins released from sensory nerves in the anaphylactic reaction in guinea pigs in vivo, we used a selective inhibitor of neutral endopeptidase, phosphoramidon, and a selective neurokinin (NK)-1 receptor antagonist, CP-96,345. Male Hartley guinea pigs were sensitized to OVA by two i.p. injections (70 mg) at 1-wk intervals. Two wk later, the animals were anesthetized and OVA was administered for 2 min by aerosol through a tracheal cannula. Plasma extravasation was assessed by the photometric measurement of the extravasated Evans blue after formamide extraction. Administration of aerosolized OVA to sensitized guinea pigs increased dye extravasation in the trachea in a dose-dependent manner, an effect that was demonstrable 5 min after exposure to allergen and that reached a maximum 10 min after exposure. At 5 min after OVA (5%), phosphoramidon (2.5 mg/kg, i.v.) did not increase the amount of dye in the trachea significantly and CP-96,345 (4 mg/kg) did not decrease the extravasated dye. At 10 min after OVA, allergen-induced plasma extravasation was potentiated by phosphoramidon by 56%, and was inhibited by CP-96,345 (4 mg/kg) by 42%. In the presence of phosphoramidon, CP-96,345 reduced the OVA-evoked plasma extravasation at 10 min in a dose-related manner (0.1-4 mg/kg). CP-96,345 (4 mg/kg) did not affect plasma extravasation induced by platelet-activating factor (100 nmol/kg, i.v.). These results suggest that tachykinin release from sensory nerves after allergen challenge to airways in sensitized guinea pigs is not responsible for the early increase in plasma extravasation, but, tachykinin release appears to play an important role in the subsequent extravasation.

Role of neurogenic inflammation in antigen-induced vascular extravasation in guinea pig trachea

Conflicting results have been reported about the role of sensory nerves in the allergen-induced plasma extravasation in sensitized guinea pigs using capsaicin desensitization. To investigate the role of tachykinins released from sensory nerves in the anaphylactic reaction in guinea pigs in vivo, we used a selective inhibitor of neutral endopeptidase, phosphoramidon, and a selective neurokinin (NK)-1 receptor antagonist, CP-96,345. Male Hartley guinea pigs were sensitized to OVA by two i.p. injections (70 mg) at 1-wk intervals. Two wk later, the animals were anesthetized and OVA was administered for 2 min by aerosol through a tracheal cannula. Plasma extravasation was assessed by the photometric measurement of the extravasated Evans blue after formamide extraction. Administration of aerosolized OVA to sensitized guinea pigs increased dye extravasation in the trachea in a dose-dependent manner, an effect that was demonstrable 5 min after exposure to allergen and that reached a maximum 10 min after exposure. At 5 min after OVA (5%), phosphoramidon (2.5 mg/kg, i.v.) did not increase the amount of dye in the trachea significantly and CP-96,345 (4 mg/kg) did not decrease the extravasated dye. At 10 min after OVA, allergen-induced plasma extravasation was potentiated by phosphoramidon by 56%, and was inhibited by CP-96,345 (4 mg/kg) by 42%. In the presence of phosphoramidon, CP-96,345 reduced the OVA-evoked plasma extravasation at 10 min in a dose-related manner (0.1-4 mg/kg). CP-96,345 (4 mg/kg) did not affect plasma extravasation induced by platelet-activating factor (100 nmol/kg, i.v.). These results suggest that tachykinin release from sensory nerves after allergen challenge to airways in sensitized guinea pigs is not responsible for the early increase in plasma extravasation, but, tachykinin release appears to play an important role in the subsequent extravasation.

Atypical beta-adrenoceptor- (beta 3-adrenoceptor) mediated relaxation of canine isolated bronchial smooth muscle

To determine whether atypical beta-adrenoceptors (beta 3-adrenoceptors) exist in the airway smooth muscle, we studied isolated bronchial segments from dogs under isometric conditions in vitro. Addition of beta-adrenoceptor agonists produced a concentration-dependent relaxation of tissues precontracted with 10(-5) M acetylcholine, rank-order potency being isoproterenol (1) > or = salbutamol (0.95) > or = BRL 37344, a beta 3-selective adrenoceptor agonist (0.83) > norepinephrine (0.10). Under the condition that alpha- and beta 1-adrenoceptors had been blocked, the relaxant response to salbutamol was competitively antagonized by the beta 2-adrenoceptor antagonist ICI 118551 and the pA2 was 7.01 +/- 0.25 (SE), whereas the response to BRL 37344 was resistant, with an apparent pA2 of 5.66. However, cyanopindolol, an antagonist for atypical beta-adrenoceptors, antagonized the BRL-induced relaxation in a competitive manner, with a pA2 of 6.74 +/- 0.11. This pA2 was lower than that when salbutamol was used as an agonist (P < 0.05). Intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels were increased by BRL 37344 in a concentration-dependent fashion. These results suggest that beta 3-adrenoceptors may exist in canine bronchial smooth muscle and that the stimulation of this type of receptor causes a bronchodilation through a cAMP-dependent pathway.

Angiotensin II potentiates neurally mediated contraction of rabbit airway smooth muscle

The effect of angiotensin II (AT II) on cholinergic neurotransmission in rabbit tracheal segments was studied under isometric conditions in vitro. AT II concentration-dependently potentiated the contractile response to electrical field stimulation (EFS), and caused a leftward shift of the frequency-response curves for EFS, so that the stimulus frequency required to produce a half-maximal effect (ES50), decreased from 7.0 +/- 0.1 to 3.0 +/- 0.1 Hz (P less than 0.01). In contrast, the contractile response to acetylcholine was not affected. Non-peptide AT II receptor antagonist CV-2961 attenuated the effect of AT II on the EFS-induced contraction. Pretreatment of tissues with thiorphan or phosphoramidon did not alter the action of AT II. Thus, AT II may prejunctionally potentiate the neurally-mediated contraction of airway smooth muscle through activation of AT II receptors on the cholinergic nerve terminals, and this effect may not be modulated by endogenous neutral endopeptidase.

Non-opioid-dependent inhibitory action of loperamide on cholinergic neurotransmission in canine isolated bronchial smooth muscle

The effect of loperamide on cholinergic neurotransmission in canine bronchial smooth muscle was studied under isometric conditions in-vitro. Addition of loperamide decreased contractile responses to electrical field stimulation in a dose-dependent fashion, the maximal decrease from the control response and the IC50 value being 65.4 +/- 5.9% and 1.5 microM, respectively. In contrast, loperamide was without effect on the responses to exogenously administered acetylcholine. The inhibitory effect of loperamide was not altered by pre-incubation of tissues with propanol, 6-hydroxydopamine, bicuculline, or naloxone. These results suggest that loperamide attenuates the neurally mediated airway contraction probably by inhibiting acetylcholine release from cholinergic nerve terminals through a non-opioid-dependent mechanism.

Alveolar attachments in emphysema of human lungs

We have studied alveolar attachments to membranous bronchioles in 41 patients enrolled in the National Institutes of Health Intermittent Positive Pressure Breathing Trial who died, came to autopsy, and provided adequate tissue for examination. The patients had moderate to severe chronic airflow obstruction and, on the average, severe emphysema. We measured the number of normal attachments per membranous bronchiole per case (N), the number of normal attachments per mm of circumference per bronchiole per case (Nunit), and the ratio of abnormal to all attachments (R). All measurements correlated closely to all measurements of emphysema and to irregular shape of bronchioles (deformity index). Measurement of abnormal attachments correlated with abnormal tests of pulmonary function, including evidence of airflow obstruction and diffusing capacity for carbon monoxide (DLCO). Nunit showed the most frequent correlations, but both N and Nunit were only related independently of emphysema for Phase III of the single-breath nitrogen test. R was related to loss of DLCO. We conclude that loss of attachments is not itself a cause of airflow obstruction but rather a correlate of emphysema, which is the proximate cause of the obstruction. Loss of alveolar attachments has an effect only on the single-breath nitrogen tests independent of emphysema.

Effects of platelet-activating factor on bioelectric properties of cultured tracheal and bronchial epithelia

To elucidate the effect of platelet-activating factor (PAF) on ion transport function of airway epithelial cells, we studied bioelectric properties of cultured tracheal and bronchial epithelia from dogs under short-circuit conditions in vitro. Addition of PAF (10(-5) mol/L) to mucosal solution of Ussing chamber increased short-circuit current of tracheal epithelium from 3.3 +/- 0.7 to 8.5 +/- 1.2 microA/cm2 (p less than 0.001). This effect was dose dependent, and there was a corresponding increase in transepithelial potential difference. In contrast, PAF was without effect when it was added to the submucosal side. Electrical properties of bronchial epithelium remained unchanged by PAF. The PAF-induced increase in short-circuit current was not affected by amiloride but abolished by diphenylamine-2-carboxylate, bumetanide, or Cl-free medium. The effects of PAF were not altered by AA-861 or U-60257, but attenuated by indomethacin and piroxicam, and dose-dependently blocked by CV 6209 and WEB 2086. Mucosal, but not submucosal, addition of PAF increased the rate of prostaglandin release from tracheal epithelium. These results suggest that PAF selectively stimulates Cl secretion across tracheal epithelium, probably through activation of its specific receptors and the subsequent production of prostaglandins.

IgE-dependent activation of alveolar macrophages augments neurally mediated contraction of small airways

1. We studied the effect of immunologically activated pulmonary alveolar macrophages (PAM) on functions of canine bronchiolar smooth muscle under isometric conditions in vitro. 2. PAM, stimulated with monoclonal anti-dinitrophenyl (DNP) IgE antibody and DNP-human serum albumin (DNP-HSA), augmented the contractile responses of bronchioles to electrical field stimulation, whereas PAM treated with IgE antibody alone had no effect. 3. In contrast, the contractile responses to exogenously administered acetylcholine were not influenced by immunologically activated PAM. 4. The PAM-induced increase in the contractile responses to field stimulation was inhibited by pretreatment of PAM with indomethacin and by addition of the thromboxane A2 (TxA2) receptor antagonist SQ 29548. 5. The release of TxA2 from PAM was increased by anti-DNP IgE and DNP-HSA, an effect that was prevented by indomethacin. 6. These results suggest that PAM may play a role in the development of antigen-induced hyperreactivity of small airways through an IgE-dependent release of TxA2 which potentiates prejunctionally the parasympathetic component of bronchiolar smooth muscle tone.

Synthesis and antiestrogenic activity of the compounds related to the metabolites of (E)-4-[1-[4-[2-(dimethylamino)ethoxy]phenyl]- 2-(4-isopropylphenyl)-1-butenyl]phenyl monophosphate (TAT-59) [corrected]

The metabolites of (E) [corrected]-4-[1-[4-[2-dimethylamino)ethoxy]phenyl]- 2-(4-isopropylphenyl)-1-butenyl]phenyl monophosphate, TAT-59, (1), a potent antitumor agent for hormone-dependent tumors, and derivatives of TAT-59 were synthesized to confirm its proposed structure. The structure and the Z-configuration of the metabolites (2a-8a) were confirmed by comparison with synthesized authentic compounds. All of the metabolites and the derivatives of TAT-59 were tested for a binding affinity toward estrogenic receptors in vitro and antiuterotrophic activity in vivo. Most of the metabolites possessed remarkable binding affinity toward estrogenic receptors as well as fairly good antiuterotrophic activity.