Biomedical subjects

M Shigyo

Publications and source records attributed to M Shigyo.

At least 19 recordsLinked to original sources

PubMed2006

Direct comparison between genomic constitution and flavonoid contents in Allium multiple alien addition lines reveals chromosomal locations of genes related to biosynthesis from dihydrokaempferol to quercetin glucosides in scaly leaf of shallot (Allium cepa L.).

The extrachromosome 5A of shallot (Allium cepa L., genomes AA) has an important role in flavonoid biosynthesis in the scaly leaf of Allium fistulosum-shallot monosomic addition lines (FF+nA). This study deals with the production and biochemical characterisation of A. fistulosum-shallot multiple alien addition lines carrying at least 5A to determine the chromosomal locations of genes for quercetin formation. The multiple alien additions were selected from the crossing between allotriploid FFA (female symbol) and A. fistulosum (male symbol). The 113 plants obtained from this cross were analysed by a chromosome 5A-specific PGI isozyme marker of shallot. Thirty plants were preliminarily selected for an alien addition carrying 5A. The chromosome numbers of the 30 plants varied from 18 to 23. The other extrachromosomes in 19 plants were completely identified by using seven other chromosome markers of shallot. High-performance liquid chromatography analyses of the 19 multiple additions were conducted to identify the flavonoid compounds produced in the scaly leaves. Direct comparisons between the chromosomal constitution and the flavonoid contents of the multiple alien additions revealed that a flavonoid 3'-hydroxylase (F3'H) gene for the synthesis of quercetin from kaempferol was located on 7A and that an anonymous gene involved in the glucosidation of quercetin was on 3A or 4A. As a result of supplemental SCAR analyses by using genomic DNAs from two complete sets of A. fistulosum-shallot monosomic additions, we have assigned F3'H to 7A and flavonol synthase to 4A.

Allium↗

PubMed2003

Transmission of alien chromosomes from selfed progenies of a complete set of Allium monosomic additions: the development of a reliable method for the maintenance of a monosomic addition set.

Selfed progeny of a complete set of Allium fistulosum - Allium cepa monosomic addition lines (2n = 2x + 1 = 17, FF+1A-FF+8A) were produced to examine the transmission rates of respective alien chromosomes. All eight types of the selfed monosomic additions set germinable seeds. The numbers of chromosomes (2n) in the seedlings were 16, 17, or 18. The eight extra chromosomes varied in transmission rate (%) from 9 (FF+2A) to 49 (FF+8A). The complete set of monosomic additions was reproduced successfully by self-pollination. A reliable way to maintain a set of Allium monosomic additions was developed using a combination of two crossing methods, selfing and female transmission. FF+8A produced two seedlings with 18 chromosomes. Cytogenetical analyses, including GISH, showed that the seedlings were disomic addition plants carrying two entire homologous chromosomes from A. cepa in an integral diploid background of A. fistulosum. Flow cytometry analysis showed that a double dose of the alien 8A chromosome caused fluorescence intensity values spurring in DNA content, and isozyme analysis showed increased glutamate dehydrogenase activity at the gene locus Gdh-1.

Allium↗

PubMed2001

N-omega-nitro-L-arginine methyl ester increases airway responsiveness to serotonin but not to acetylcholine in cats in vivo.

BACKGROUND: We previously reported that N(omega)-nitro-L-arginine methyl ester (L-NAME) enhances airway responsiveness to inhaled serotonin in cats treated with atropine and propranolol. OBJECTIVE: To further elucidate the role of nitric oxide (NO) in airway responsiveness, we investigated whether L-NAME induces airway hyperresponsiveness to serotonin and acetylcholine (ACh) in animals with intact innervation. METHODS: Cats were anesthetized with pentobarbital sodium (50 mg/kg, i.p.), and mechanically ventilated. To assess airway responsiveness, we measured increase in total pulmonary resistance (RL) produced by delivering serotonin or ACh aerosol to the airway, and determined PC200 (the concentration which caused a 200% increase in RL). RESULTS: The following results were obtained: (1) Airway responsiveness to serotonin was significantly enhanced by the administration of L-NAME (100 mg/kg) in animals treated with atropine and propranolol. (2) Airway responsiveness to serotonin was also significantly enhanced by L- NAME in animals with intact innervation. (3) In contrast, airway responsiveness to ACh was not changed by the addition of L-NAME in cats with intact innervation. CONCLUSION: These results suggest that NO modulates nonspecific airway responsiveness in animals with intact innervation, presumably by a reflex mechanism.

Acetylcholine↗

PubMed2001

Molecular followup of newly diagnosed bladder cancer using urine samples.

PURPOSE: Patients with superficial bladder cancer can be treated with transurethral resection. However, 50% to 70% of them have intravesical recurrence after transurethral resection and muscle invasive disease develops in 10% to 20%, which is eventually indicated for radical cystectomy. Therefore, reliable predictors of intravesical recurrence are required for management of superficial bladder cancer. We investigated whether detection of the loss of heterozygosity in urine samples would be available as a sensitive diagnostic modality for recurrence of bladder cancer. MATERIALS AND METHODS: Urine samples, cancer tissue and peripheral blood lymphocytes were obtained from 37 patients with newly diagnosed bladder cancer, and analyzed for the loss of heterozygosity on chromosomes 9 and 17p by single strand DNA conformation polymorphism analysis. RESULTS: Chromosomal loss was detected on 24 (65%) cancer tissues and 26 (70%) urine samples. The loss of heterozygosity on chromosome 17p was detected in 19 (51%) urine samples, mostly in cancers with higher grades and/or stages. During postoperative followup of 24 patients with superficial bladder cancer who had undergone transurethral resection, intravesical recurrence did not develop in 9 of 10 without chromosomal aberrations in urine samples. In contrast, intravesical recurrence developed in 11 of 14 patients who had a loss of heterozygosity in urine samples. This loss showed a significant correlation with the intravesical disease-free period (p = 0.004). Multivariate analysis revealed that the loss of heterozygosity in urine samples was a significant predictor of intravesical recurrence. CONCLUSIONS: Detection of the loss of heterozygosity in urine samples is available as a sensitive marker for predicting intravesical recurrence of superficial bladder cancer.

Adult↗

PubMed2000

Pituitary adenylate cyclase activating peptide mediates inhibitory nonadrenergic noncholinergic relaxation.

We investigated the contribution of pituitary adenylate cyclase activating peptide (PACAP) to inhibitory nonadrenergic noncholinergic (inhibitory-NANC) relaxation of tracheal smooth muscle in cats. We also investigated the roles of vasoactive intestinal peptide (VIP) and nitric oxide (NO) on this function. Smooth muscle strips prepared from feline trachea were precontracted with 1 microM serotonin, and inhibitory-NANC relaxation was induced by electrical-field stimulation in the presence of atropine and propranolol. PACAP-(6-38) (a selective antagonist of PACAP; 1, 3 and 10 microM), VIP-(10-28) (a selective antagonist of VIP; 1, 3 and 10 microM) and N(omega)-nitro-L-arginine methyl ester (L-NAME, a selective NO synthase inhibitor; 3, 10 and 30 microM) each partially but significantly attenuated the amplitude of inhibitory-NANC relaxation. The effects of PACAP-(6-38) and VIP-(10-28) were additive. Addition of PACAP-(6-38) and/or VIP-(10-28) further attenuated relaxation in the presence of L-NAME. These results suggest that PACAP, VIP and NO contribute to the relaxation induced by inhibitory-NANC in tracheal smooth muscle in cats, and that they mediate this relaxation via different pathways.

Animals↗

PubMed1999

Effect of inhaled glucocorticoid on the cellular profile and cytokine levels in induced sputum from asthmatic patients.

Cytokines are considered to play a role in the airway inflammation of bronchial asthma. We examined the cellular profile and cytokine levels in induced sputum samples obtained before and after treatment with beclomethasone dipropionate (BDP, 800 microg/day, for 4 weeks) in 12 mild to moderate asthmatic subjects who had not previously received inhaled glucocorticosteroids. Sputum was induced with a 20-min inhalation of 3% saline by an ultrasonic nebulizer. The freshly expectorated sputum separated from the saliva was analyzed for cell counts, for the concentration of interleukin-8 (IL-8), and for the concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF). The mean percentage of eosinophils in the sputum samples decreased significantly after BDP treatment, but no significant change in the percentage of neutrophils was observed. The mean IL-8 and GM-CSF levels also decreased significantly after treatment. The BDP treatment was associated with an increase in the mean peak expiratory flow (PEF) and with a decrease in the diurnal variation of PEF. These results suggest that inhaled steroids improve airway inflammation and lung function in asthmatics, presumably in part by inhibiting the synthesis of inflammatory cytokines such as IL-8 and GM-CSF.

Administration, Inhalation↗

PubMed1999

Effect of the Chinese herbal medicine, Bakumondo-to, on airway hyperresponsiveness induced by ozone exposure in guinea-pigs.

OBJECTIVE: Bakumondo-to (Maimendong tang) is a Chinese herbal medicine that has been used as an anti-tussive agent. However, the effects of Bakumondo-to on airway hyperresponsiveness are unknown. We examine whether Bakumondo-to can inhibit airway hyperresponsiveness induced by ozone. METHODOLOGY: Measurements of airway responsiveness and plasma extravasation and bronchoalveolar lavage (BAL) were performed before and after ozone exposure (3 p.p.m., 2 h). Guinea-pigs were anaesthetized with pentobarbital sodium and mechanically ventilated. Airway responsiveness was determined by an inhalation of doubling concentration of histamine, and the concentration of histamine required to produce a 200% increase in R(L) (PC200) was calculated by log-linear interpolation. Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway. RESULTS: Ozone produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. Bakumondo-to (400 mg/kg p.o.) significantly inhibited airway hyperresponsiveness, but had no effect on neutrophil influx or plasma extravasation. CONCLUSIONS: We demonstrated that Bakumondo-to can attenuate airway hyperresponsiveness induced by ozone without affecting airway inflammation, which suggests that Bakumondo-to may act on the subsequent mechanisms after the induction of inflammation, such as mediator release.

Airway Resistance↗

PubMed1998

Allelic loss on chromosome 9 in bladder cancer tissues and urine samples detected by blunt-end single-strand DNA conformation polymorphism.

Allelic loss on chromosome 9 is the most frequent and earliest genetic event in bladder carcinogenesis, and its detection in urine samples would be useful for detecting bladder cancer. A highly sensitive method to detect loss of heterozygosity (LOH) at 5 polymorphic loci on chromosome 9p and 9q was developed by the use of blunt-end single-strand DNA conformation polymorphism (blunt-end SSCP) analysis. Tumor tissues, urine samples and peripheral blood lymphocytes from 34 patients with transitional cell carcinoma of the bladder were analyzed. LOHs on 9p and/or 9q were found in 24 (71%) of 34 tumor samples and 23 (70%) of 33 urine samples, while no allelic loss was detected in 20 urine samples from benign urothelial diseases. The frequency of allelic loss in tumor tissues was 67%, 71% and 80% in the pTa, pT1 and > or = pT2 stages and 50%, 80% and 79% in G1, G2 and G3 tumors, respectively. In comparison with a urine cytological examination, LOH on chromosome 9 was detected in 70% of urine samples diagnosed as transitional cell carcinoma, 67% of those as atypia and 70% of those as no malignant cells. Thus, detection of LOH on chromosome 9 from urine samples by blunt-end SSCP is a more sensitive diagnostic modality than cytologic examination for detecting bladder cancer. It would be useful for postoperative management of bladder cancer, particularly when the allelic loss is revealed in the tumor tissues obtained at first surgery.

Carcinoma, Transitional Cell↗

PubMed1998

Role of adrenergic nervous system in cigarette smoke-induced bronchoconstriction in guinea pigs.

The goal of this study was to clarify the role of the adrenergic nervous system in bronchoconstriction induced by exposure to cigarette smoke in guinea pigs. Artificially ventilated animals were exposed to 160 puffs of smoke for 8 min. Bronchoconstriction was assessed as a percentage of the baseline total pulmonary resistance (RL). The effects of pretreatment with phentolamine (0.1 mg/kg, i.v.), propranolol (1 mg/kg, i.v.), and/or atropine (1 mg/kg, i.v.) were evaluated. Exposure to cigarette smoke caused significant bronchoconstriction. Phentolamine, an alpha-adrenoceptor antagonist, significantly inhibited cigarette smoke-induced bronchoconstriction, while propranolol, a beta-adrenoceptor antagonist, significantly enhanced it. Combined use of these compounds further enhanced the bronchoconstriction. All of modulations of the bronchoconstriction by adrenoceptor antagonists were completely abolished by pretreatment with atropine. Phentolamine and/or propranolol had no effect on the bronchoconstriction induced by inhaled acetylcholine. Pretreatment with yohimbine (0.5 mg/kg, i.v.), a selective alpha2-adrenoceptor antagonist, showed modulatory effects similar to those of phentolamine on cigarette smoke-induced bronchoconstriction. These results suggest that cigarette smoke-induced bronchoconstriction is regulated by the prejunctional modulation of the cholinergic system via alpha- and beta-adrenoceptors. This mechanism may be modulated by the autoregulation of adrenergic nerves via the alpha2-autoreceptor.

Acetylcholine↗

PubMed1998

Treatment for advanced testicular cancer with high-dose chemotherapy and autologous blood stem cell transplantation.

BACKGROUND: This study was carried out to investigate the efficacy and safety of high-dose chemotherapy (HDC) for the treatment of patients with advanced testicular cancer. METHODS: Seven patients were treated with high-dose carboplatin, etoposide, and ifosfamide followed by autologous blood stem cell transplantation. One patient received 1 cycle, 4 patients received 2 cycles, and 2 patients received 3 cycles of HDC. We performed a total of 15 autologous blood stem cell transplantations: 8 with autologous bone marrow; 6 with peripheral blood stem cells; and 1 with peripheral blood stem cells in addition to autologous bone marrow. RESULTS: Four of the 7 patients achieved a pathologic complete response via early use of HDC and additional salvage surgery. All 4 patients are still alive without evidence of disease at 12, 30, 33, and 54 months, respectively. One patient is alive with active disease at 35 months. Two patients refractory to conventional chemotherapy died of progressive disease at 5 and 27 months, respectively. The hematologic recovery after HDC was rapid, and peripheral blood stem cells tended to have shorter hematologic recovery compared with those from autologous bone marrow, although the difference was not significant. Nonhematologic toxicity was usually mild and manageable. CONCLUSION: High-dose chemotherapy, followed by autologous blood stem cell transplantation, may be safe and effective for patients with advanced testicular cancer, particularly when early use of HDC is conducted for chemotherapy-sensitive patients. A further large, long-term, follow-up study will be needed to define the role of HDC.

Adolescent↗

PubMed1998

Pituitary adenylate cyclase activating peptide regulates neurally mediated airway responses.

To clarify the protective effects of pituitary adenylate cyclase activating peptide (PACAP) on airway narrowing, we examined the effects of PACAP on smooth muscle contraction and plasma extravasation in guinea-pig airways. Smooth muscle contraction evoked by electrical field stimulation (EFS) or exogenously applied acetylcholine (ACh) or substance P (SP) was measured before and after PACAP in vitro. The effect of PACAP on airway plasma extravasation was also measured in vivo. In trachea, PACAP (10(-9) - 10(-7) M) significantly suppressed smooth muscle contraction evoked by EFS without affecting ACh sensitivity, suggesting that PACAP inhibits cholinergic neuroeffector transmission. In the main bronchi, PACAP (10(-9) - 10(-8) M) significantly suppressed the contraction evoked by EFS without affecting SP sensitivity in the presence of atropine, suggesting that PACAP inhibits SP release from excitatory nonadrenergic noncholinergic (eNANC) nerves. In animals treated with atropine and propranolol, PACAP attenuated the increase in plasma extravasation induced by electrical vagus stimulation or by SP. These results suggest that pituitary adenylate cyclase activating peptide may play a role in modulation of airway responses through inhibition of cholinergic and noncholinergic mechanisms.

Acetylcholine↗

PubMed1998

Eosinophilic airway inflammation induced by repeated exposure to cigarette smoke.

Acute exposure to cigarette smoke causes airway hyperresponsiveness (AHR) in guinea-pigs, which resolves within a few hours. Repeated exposure may have a different effect on the airways. To address this question, guinea-pigs were repeatedly exposed to cigarette smoke (six cigarettes for 1 h x day(-1)) for 14 consecutive days. Airway responsiveness to inhaled histamine and differential cell counts in bronchoalveolar lavage fluid (BALF) were evaluated 1 day after the last exposure. Significant neutrophilia in BALF was observed after 3 days of smoke exposure. Significant eosinophilia in BALF and AHR were observed after 14 days of smoke exposure, but not after 3 or 7 days of smoke exposure. These changes persisted until 3 days after the last exposure and resolved 7 days afterwards. Histologically, the recruited eosinophils were observed predominantly in the airways, but not in the alveoli. Treatment with E-6123, a specific platelet-activating factor receptor antagonist (1 mg x kg(-1) x day(-1) p.o. during smoke exposure) significantly inhibited the eosinophil influx and AHR. Repeated exposure to cigarette smoke may induce prolonged airway inflammation and airway hyperresponsiveness in guinea-pigs. Platelet-activating factor or platelet-activating factor-like lipids may play a key role in airway hyperresponsiveness, presumably by the induction of eosinophilic airway inflammation.

Animals↗

PubMed1997

The effects of a specific tachykinin receptor antagonist FK-224 on ozone-induced airway hyperresponsiveness and inflammation.

We have demonstrated previously that tachykinin depletion by capsaicin prevented the ozone-induced airway hyperresponsiveness and the bronchial wall oedema in guinea pigs. To further clarify the role of neurogenic inflammation in ozone-induced airway hyperresponsiveness, we investigated the effects of a specific tachykinin receptor antagonist (FK-224) in guinea pigs. Animals were anaesthetized, tracheostomized and mechanically ventilated. Total pulmonary resistance (RL) was calculated from transpulmonary pressure and box flow in a plethysmograph. Airway responsiveness was assessed by determining the provocative concentration of histamine aerosol that increased RL to twice the baseline value (PC200). Animals were injected with either FK-224 (10 mg/kg, dissolved in 0.2 mL/kg DMSO) or vehicle (0.2 mL/kg DMSO) intravenously, then pre-ozone PC200 was determined. Following this measurement, animals were exposed to 3 ppm ozone for 60 min. Immediately after exposure, the histamine dose response curve was evaluated again. Bronchoalveolar lavage (BAL) was performed in animals treated with FK-224 or vehicle. In animals treated with vehicle, ozone exposure caused significant decrease in PC200 and moderate increase in neutrophils in BAL fluid. FK-224 pre-treatment significantly inhibited ozone-induced hyperresponsiveness. Neutrophils in BAL fluid did not significantly increase after ozone exposure in animals treated with FK-224. By contrast, the degree of epithelial desquamation did not differ significantly between the two groups. We conclude that neurogenic inflammation caused by tachykinin release may be responsible for ozone-induced bronchial hyperresponsiveness, and that tachykinins may play a role in the initiation of airway inflammation.

Airway Resistance↗

PubMed1997

Pre- and post-junctional effects of VIP-like peptides in guinea pig tracheal smooth muscle.

To determine the role of VIP-like peptides on neurotransmission of vagus nerve, we evaluated the effects of helodermin, helospectin, and vasoactive intestinal peptide (VIP) on the contraction of guinea pig tracheal smooth muscle evoked by electrical field stimulation (EFS) or the exogenous application of actylcholine (ACh). Isometric tension of tracheal strips was measured in the presence of indomethacin (10(-6) M) and of guanethidine (10(-6) M). VIP (10(-9) M to 10(-7) M) significantly suppressed the contraction evoked by EFS. VIP, at concentrations of 10(-9) M and 10(-8) M, did not affect the ACh-evoked contraction, but a concentration of 10(-7) M suppressed ACh-evoked contraction. Helospectin and helodermin (10(-8) M and 10(-7) M) significantly suppressed the EFS-evoked contraction, but 10(-9) M showed no effect. Helospectin and helodermin had no effect on the ACh sensitivity of smooth muscle up to 10(-8) M, but a concentration of 10(-7) M suppressed the ACh-evoked contraction. These results indicate that helodermin, helospectin, and VIP exert both pre- and post-junctional inhibitory effects on the airway smooth muscle of guinea pigs. These peptides, thus, inhibited tracheal smooth muscle contraction prejunctionally at low concentrations, and acted postjunctionally at higher concentrations.

Acetylcholine↗

PubMed1997

Effect of beta 2-agonists on histamine-induced airway microvascular leakage in ozone-exposed guinea pigs.

beta 2-adrenergic agonists exhibit antipermeability effects in the airways. However, it is not known whether beta 2-agonists have this beneficial effect in airway mucosa that is already inflamed. We evaluated the effects of two inhaled beta 2-agonists, salbutamol and formoterol, on the histamine-induced bronchoconstriction and plasma extravasation in the airways of guinea pigs with or without ozone exposure. Total pulmonary resistance (RL) was measured before and after histamine inhalation in anesthetized animals that were pretreated with inhaled salbutamol, formoterol, or saline. Plasma extravasation in the airways was measured using Evans blue dye. In the control animals not exposed to ozone, salbutamol and formoterol each significantly reduced both the histamine-induced bronchoconstriction and the plasma extravasation in the trachea and main bronchi. In the ozone-exposed animals, the increase in RL after histamine was greater than that in control animals. Salbutamol and formoterol each significantly reduced histamine-induced bronchoconstriction, even in the ozone-exposed animals. Salbutamol did not affect the histamine-induced plasma extravasation, whereas formoterol reduced the plasma extravasation in the main bronchi, but not in the trachea, of the animals exposed to ozone. These results suggest that the anti-inflammatory properties of formoterol in inflamed airways may contribute to the beneficial effects in the treatment of airway inflammation.

Adrenergic beta-Agonists↗

PubMed1996

Thromboxane A2 mimetic (U-46619) induces hyperresponsiveness of smooth muscle in the canine bronchiole, but not in the trachea.

It has been reported that cholinergic agonists induce bronchoconstriction by directly stimulating M3 muscarinic receptors on the surfaces of smooth muscle cells. Although thromboxane A2 (TXA2) has been demonstrated to induce airway hyperresponsiveness to cholinergic agonists in vivo, it does not affect the contractile response of smooth muscle to cholinergic agonists in vitro. To investigate the causes for the discrepancy between the in vivo and in vitro data, we compared the effects exerted by a TXA2 mimetic, U-46619, on the smooth muscle of canine trachea and bronchiole. We measured the contractile response to exogenously applied acetylcholine (ACh) before and after the application of a subthreshold dose of U-46619. The subthreshold dose was determined as that dose which did not induce smooth muscle contraction, this being 10(-9) M in the present study. The contractile responses of tracheal strips to ACh were not affected by the subthreshold dose of U-46619. By contrast, the responses of bronchiolar rings were significantly enhanced by this subthreshold dose. The excitatory effect of U-46619 on the ACh-induced contraction was completely prevented by treatment with a TXA2 antagonist, BAY u3405. These results indicate that TXA2 directly increases the responsiveness of smooth muscle in the bronchiole, and suggest that increases in the responsiveness of small airways may play an important role in the development of the airway hyperresponsiveness induced by TXA2.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1996

Thromboxane causes airway hyperresponsiveness after cigarette smoke-induced neurogenic inflammation.

We investigated the role of neurogenic inflammation and the subsequent mechanisms in cigarette smoke-induced airway hyperresponsiveness in guinea pigs. Exposure to cigarette smoke was carried out at tidal volume for 3 min. Airway responsiveness to histamine was determined before and after smoke exposure followed by bronchoalveolar lavage (BAL). Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway. Cigarette smoke produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. FK-224 (10 mg/kg i.v.), a tachykinin antagonist at NK1 and NK2 receptors, significantly inhibited these changes. The thromboxane (Tx) B2 concentration was increased in BAL fluid after smoke exposure and was significantly inhibited by FK-224. OKY-046 (10 mg/kg i.v.), a Tx synthase inhibitor, significantly inhibited airway hyperresponsiveness but had no effect on neutrophil influx or plasma extravasation. The results suggest that neurogenic inflammation and the subsequent generation of Tx in the airway are important in the development of the airway hyperresponsiveness induced by cigarette smoke.

Animals↗

PubMed1996

Role of thromboxane-A2 and cholinergic mechanisms in bronchoconstriction induced by cigarette smoke in guinea-pigs.

Acute exposure to cigarette smoke provokes bronchoconstriction and increases the concentration of thromboxane (Tx) A2 in bronchoalveolar lavage (BAL) fluid. The purpose of this study was to investigate the role of TxA2 and cholinergic mechanisms in the airway response induced by exposure to cigarette smoke in guinea-pigs. Anaesthetized animals were exposed to 200 puffs of smoke for 10 min. The amount of Evans blue dye extravasated into the bronchial tissue was then measured BAL was performed to determine cell counts and the concentration of TxB2, a stable metabolite of TxA2. The effects of pretreatment with a Tx synthase inhibitor, OKY-046 (10 mg.kg-1), and/or atropine (1 mg.kg-1) were evaluated. Exposure to cigarette smoke caused significant bronchoconstriction (284 +/- 33% of baseline pulmonary resistance (RL)) and plasma extravasation (30.0 +/- 3.8 vs 16.8 +/- 2.6 ng.mg-1 of sham control; main bronchi). OKY-046 or atropine significantly inhibited the bronchoconstriction to a similar extent, without affecting the plasma extravasation. Combined use of these compounds had no additive effect. The cigarette smoke caused significant increase in TxB2 (48 +/- 10 vs 14 +/- 1 pg.mL-1 of sham control) in BAL fluid, which was abolished by OKY-046 but not by atropine. The cellularity in BAL fluid was not different among groups. These results suggest that the bronchoconstriction induced by cigarette smoke is partially mediated by thromboxane A2, which is dependent on a cholinergic pathway.

Animals↗