Increased lung neutrophil apoptosis and inflammation resolution in nonresponding pneumonia.

Neutrophil activation state and its relationship with an inflammatory environment in community-acquired pneumonia (CAP) remain insufficiently elucidated. We aimed to evaluate the neutrophil apoptosis and cytokine pattern in CAP patients after 72 h of treatment, and their impact on infection resolution. Apoptosis of blood and bronchoalveolar lavage (BAL) neutrophils was measured in nonresponding CAP (NCAP), in responding CAP (blood only) and in patients without infection (control). Pro-inflammatory (interleukin (IL)-6, IL-8) and anti-inflammatory (IL-10) cytokines were measured. Main outcomes were clinical stability and days of hospitalisation. Basal neutrophil apoptosis was higher in the BAL and blood of NCAP, whereas spontaneous apoptosis (after 24 h culture) was lower. Cytokines in NCAP were higher than in responding CAP and control: IL-6 was increased in BAL and blood, IL-8 in BAL and IL-10 in blood. An increased basal apoptosis (≥20%) in BAL of NCAP was associated with lower systemic IL-10 (p<0.01), earlier clinical stability (p=0.05) and shorter hospital stay (p=0.02). A significant correlation was found for systemic IL-6 and IL-10 with days to reach stability and length of stay. After 72 h of treatment, an increased basal alveolar neutrophil apoptosis might contribute to downregulation of inflammation and to faster clinical stability.

[Does experience influence perception of dyspnea?]. / Influye la experiencia en la percepción de disnea?

OBJECTIVE: The perception of somatic sensations like dyspnea can be influenced by such factors as an individual s personality, experiences, or ability to adapt to stimuli. Our aim was to determine whether the perception of acute bronchoconstriction is different for patients with asthma and patients who have never experienced an episode of airway obstruction. PATIENTS AND METHOD: We studied 2 groups of patients. The first consisted of 24 subjects with intermittent rhinitis and asthma (10 females and 14 males) with a mean (SD) age of 25 (7) years. All reported not feeling dyspnea at rest on a Borg scale. The second group consisted of 24 subjects who only had rhinitis but no lung disease (no episode of asthma) or dyspnea at rest (12 females and 12 males) with a mean age of 27 (6) years. There were no significant differences between the groups with regard to sex, smoking, economic or educational level, anxiety (determined by the trait portion of the State-Trait Anxiety Inventory), depression (Beck Depression Inventory), or spirometric parameters. All took a histamine bronchial provocation test in which the patient assessed dyspnea on a modified Borg scale after each histamine dose. The provocation dose needed to produce a 20% decrease (PD20) in forced expiratory volume in the first second (FEV1) was calculated. We also recorded dyspnea perception score when FEV1 fell 5%, 10%, 15%, and 20%. RESULTS: No dyspnea was perceived at PS20 by 12.5% of the asthmatics and by 45% of nonasthmatics (P< .0001). The mean PS20 was 2.4 (2.1) (range, 0-7) in the first group and 0.37 (0.48) (range, 0-3) in the second (P< .0001). More asthma patients than nonasthmatics perceived dyspnea at all degrees of bronchial obstruction. PD20 was different in the 2 groups (1.6 [2] vs 6.03 [5] for the first and second groups, respectively; P< .003), but there was no significant relation between PD20 and PS20 (Spearman s correlation coefficient, 0.19; P= .221). CONCLUSION: Our findings support the hypothesis that appropriate perception of dyspnea is grounded in prior experience and learning.

[Evolution over time in over perceivers of dyspnea in asthma]. / Evolución temporal de la percepción exagerada de disnea en los pacientes con asma.

OBJECTIVE: In previous studies we identified a subgroup of patients whose perception of breathlessness was exaggerated during acute bronchoconstriction and who were termed "over perceivers" or "hyperperceivers". In this study we aimed to determine whether such over perception is sporadic or stable over time. We also examined whether there is an association between over perception of dyspnea and hyperventilation syndrome. PATIENTS AND METHODS: The subjects were 22 stable asthmatics (11 men, 11 women) who had been over perceivers of dyspnea in a study 9 years earlier. After a medical history was taken, a patient performed forced spirometry and a severity classification was made according to the criteria of the Global Initiative for Asthma (GINA). A bronchial histamine challenge was then administered to measure dose-related perception of dyspnea on a Borg scale, according to a procedure that was similar to the one used 9 years earlier by the same investigator. The patients were also asked for a subjective assessment of the severity of their asthma (scale, 0-10) and to respond to items on the Nijmegen hyperventilation questionnaire and the trait form of the State-Trait Anxiety Inventory. RESULTS: The overall perception of severity of disease, level of anxiety, and perception of dyspnea at rest were lower after 9 years (P<.001). No change was observed in bronchial hyperresponsiveness (dose of inhaled histamine required to provoke a 20% decline in forced expiratory volume in the first second [FEV1]-PD20) or objective parameters of severity (FEV1 and GINA classification). Fourteen asthmatics (64%) were still over perceivers and the other patients had changed: 6 were normal perceivers and 2 were "poor perceivers". Only subjective perception of disease severity improved for the patients who were still over perceivers; the other patients, on the other hand, showed improvements in subjective assessments, objective ones (except PD20), and anxiety. Finally, those who remained over perceivers had higher scores for anxiety (24 vs 15; P<.05) and hyperventilation (18 vs 13; P= not significant). CONCLUSIONS: Most over perceivers of dyspnea remain so over the years and this trait is related to anxiety. We have been unable to demonstrate an association with hyperventilation syndrome.

[Prevalence of hyperventilation syndrome in patients treated for asthma in a pulmonology clinic]. / Prevalencia del síndrome de hiperventilación en pacientes tratados por asma en una consulta de neumología.

OBJECTIVE: Although the presence of hyperventilation syndrome can affect the symptoms of patients with asthma, there is very little information available regarding its frequency in Spain. The aim of this study was to investigate the prevalence of hyperventilation syndrome in the asthmatic population treated as outpatients and establish its relationship with anxiety disorders. PATIENTS AND METHOD: We studied 157 consecutive asthmatic patients (61 men and 96 women; mean [SD] age, 45 [17] years; forced expiratory volume in the first second, 84% [21%] of the predicted value) treated in our outpatients clinic. The patients had stable disease with varying degrees of severity. After collecting demographic data and medical histories, we asked the patients to complete the Spanish versions of the Anxiety Sensitivity Index, the Asthma Symptom Checklist, and the Nijmegen questionnaire; in the latter test, a score of 23 or over was considered diagnostic for hyperventilation syndrome. Finally, patients were evaluated to determine whether they had suffered from panic disorder in the last 6 months (according to the criteria of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders). RESULTS: Hyperventilation syndrome was present in 57 asthmatic patients (36%) and panic disorder in 4 patients (2%). The majority of patients with hyperventilation syndrome were women (78% vs 51%; P=.001) and were older (49 vs 42; P=.01); they displayed more basal dyspnea (1.26 vs 0.89 on the Medical Research Council scale; P=.01), greater sensitivity to anxiety (P=.001), and went to the emergency room more often for exacerbations (P=.002). Patients with hyperventilation syndrome scored significantly higher on all subscales of the Asthma Symptoms Checklist. Finally, the variables introduced in the regression analysis (stepwise) to explain the score on the Nijmegen questionnaire (r(2)=0.57) were basal dyspnea and sensitivity to anxiety. CONCLUSIONS: Approximately one third of the asthmatic patients treated in a pulmonology clinic also present hyperventilation syndrome. This cannot be explained by comorbidity of asthma with panic disorder, and is only partly linked to the symptoms associated with hyperventilation that appear during an asthma attack.

[Agreement in asthmatics' perception of dyspnea during acute and chronic obstruction]. / Concordancia entre la percepción de disnea del asmático durante la obstrucción aguda y crónica.

OBJECTIVE: Three types of asthmatic patients can be identified during periods of clinical stability: "poor perceivers," "normal perceivers," and "over perceivers." When asthmatics undergo bronchial challenge in the laboratory, the same distinctions in type of perception can be observed. The aim of the present study was to determine the level of agreement between the 2 situations. PATIENTS AND METHODS: A total of 93 patients with persistent moderate asthma (36 men and 57 women; mean age 40 years) were studied. We asked them to assess their dyspnea on a modified Borg scale when stable and after each histamine dose in a bronchial provocation test. When a patient's Borg scale assessment in stable situation was below the 25th percentile, that patient was classified as a poor perceiver. Patients were considered over perceivers if their score in stable situation was in the 75th percentile. Others were labeled normal perceivers. Type of perception during acute bronchoconstriction was defined in function of the change in Borg assessment once forced expiratory volume in the first second had decreased 20%: poor perceivers were those whose change in Borg assessment was in the 25th percentile, over perceivers were in the 75th percentile, and normal perceivers in the middle percentiles. RESULTS: In stable situation, 23 patients were poor perceivers, 58 were normal perceivers, and 12 were over perceivers. During bronchoconstriction, there were 23 poor perceivers, 47 normal perceivers, and 23 over perceivers. Agreement was estimated by a kappa index of 0.0574 for poor perception, 0.1521 for over perception, and 0.3980 for normal perception. CONCLUSIONS: Asthmatics' perception of dyspnea during periods of stability and during acute bronchoconstriction are independent phenomena. It is therefore not possible to infer how a patient will perceive an asthmatic attack by evaluating only how he or she perceives breathlessness during stable periods.

Pharmacological analysis of the responsiveness of guinea-pig lung parenchymal strip to dopamine.

Responses to dopamine were examined in the guinea-pig isolated lung parenchymal strip. Complete cumulative concentration-response curves to dopamine exhibited a biphasic pattern with a small initial contraction at concentrations below 10(-5) M followed by a dose-dependent relaxation at higher concentrations. Phentolamine (10(-5) M) completely abolished the contractile component and enhanced sensitivity and maximal relaxation to dopamine. In the presence of phentolamine, propranolol antagonized the dopamine-induced relaxation (pA2 = 8.54 +/- 0.07). In the presence of propranolol (10(-6) M), dopamine produced a dose-related contraction displaced to the right by phentolamine. Incubation with haloperidol (10(-5) M) did not modify the characteristics of the concentration-response curve to dopamine. Pretreatment with reserpine abolished the contraction to dopamine without affecting its relaxant response. Cocaine significantly increased the pD2 value of dopamine in the presence of propranolol. It is concluded that dopamine produced both relaxation of lung parenchymal strip due to direct activation of beta-adrenoceptors and contraction mediated through direct and indirect (catecholamine release) actions at alpha-adrenoceptors. There is no evidence in favour of the existence of specific dopamine-receptors in this preparation.

Diagnostic value of the bronchial provocation test with methacholine in asthma. A Bayesian analysis approach.

The Bayesian analysis was used in this study to investigate the diagnostic value of the bronchial provocation test with methacholine in patients with asthma. The best cutoff value of accumulated concentration of methacholine administered that caused a 20 percent fall in FEV1 post-saline (PC20) in our sample, determined with a receiver operator characteristic curve, was 15 mg/ml. The interval security of the test was established by a pretest probability between 0.16 and 0.87 and the best test results were obtained when pretest probability was 0.48. The positive final diagnostic gain of the test was maximal at this pretest probability. We conclude that the application of Bayes' theorem, considering the pretest probability of asthma and the sensitivity and specificity of the individual PC20 obtained, increases the accuracy of the bronchial provocation test with methacholine in the diagnosis of asthma.

Cell type accuracy of bronchial biopsy specimens in primary lung cancer.

STUDY OBJECTIVES: To evaluate the diagnostic accuracy of bronchial biopsy (BB) specimens in establishing the specific cell type in primary lung cancer (LC), and to study the influence of several factors on this accuracy. SETTING: Tertiary health-care center. PATIENTS: One hundred forty-six patients with LC diagnosed by BB specimens who underwent thoracotomy (T). MEASUREMENTS: We have studied the specific LC cell type observed in the BB specimen and compared it with the T specimen (reference diagnosis). Age, location and type of bronchial lesion, number and size of the biopsy fragments, tumoral size, sample necrosis, degree of cell differentiation, tumoral stage, pathologist's experience, and the presence of other diagnostic tests with the same cell type were analyzed to assess their influence on the concordance between the two diagnoses. RESULTS: The overall concordance between BB and T histologic diagnosis was 0.70 (kappa coefficient [K]). Of the different histologic types, the worst result was obtained in large cell carcinoma (LLC) (K, 0.49). Squamous carcinoma and adenocarcinoma gave similar results (0.74 and 0.77, respectively), while small cell lung cancer (SCLC) only reached a value of 0.60. The degree of cell differentiation, the absence of necrosis, and presence of other preoperative diagnoses were the variables that most influenced the histologic accuracy of BB specimens. Therefore, the probability of BB accuracy was 2.7, 7.7, and 25 times higher in well-differentiated, than in poorly differentiated, moderately differentiated, or undifferentiated carcinomas; 5.2 times higher when there was no necrosis in the sample; and 7.43 higher when there was another preoperative diagnosis. CONCLUSIONS: The histologic results of BB must be examined carefully, especially in cellular subtypes like LLC. The absence of differentiation and presence of necrosis in BB samples were the factors that require the greatest caution in ascertaining the cell type. When they are involved and also in all cases in which identifying the specific cell type has important implications, we prefer to classify the patients as having SCLC or non-small cell lung cancer, and then reclassify them later after using a second diagnostic technique.

Responsiveness to tyramine in isolated lung parenchymal strip of guinea-pig and rat.

The effects of alpha/beta-adrenoceptor agonists in isolated lung parenchymal strip are well characterized but information related to indirectly acting sympathomimetic agents is scarce. In the present study the response to tyramine was analyzed in lung strips from guinea-pig and rat. Tyramine elicited a dose-related contraction of the lung strip with an EC50 of 1.12 X 10(-4) M in the guinea-pig and 4.28 X 10(-4) M in the rat. Incubation with propranolol did not modify the tyramine-induced contraction but blocked the relaxation which occasionally appeared at low concentrations of tyramine. No tachyphylaxis to tyramine was detected. Cocaine (3 X 10(-5) M) and reserpine significantly increased the EC50 values of tyramine. In reserpine-treated animals, phentolamine (both animal species), clemizole (guinea-pig) and methysergide (rat) displaced to the right the concentration-response curve to tyramine but the dose ratios were significantly lower than those obtained for their specific agonists. These results suggest that in addition to the adrenergic component (catecholamine release and direct alpha-adrenoceptor activation) there is an important contribution of other receptor systems such as histamine (guinea-pig) and 5-hydroxytryptamine (rat) to the contractile response to tyramine in lung tissue.

The spasmogenic effect of caffeine in trachealis isolated from control and actively sensitized guinea-pigs.

The spasmogenic activity of caffeine (10 mM) was evaluated in tracheal strips obtained from control and sensitized guinea-pigs then pretreated with indomethacin (2.8 microM) and cooled to 20 degrees C. The contraction elicited by caffeine was inhibited by verapamil (100 microM), trifluoperazine (100 and 500 microM) and dantrolene (50 and 500 microM) in the control and the sensitized tissues but was unaffected by disodium cromoglycate (39 microM). However, the same concentration of verapamil produced significantly less inhibition of the caffeine-induced contraction in sensitized compared to control tissues while the reverse was found for trifluoperazine and dantrolene. Exposure to a Ca2+-free, EGTA-containing medium resulted in 33% inhibition of the response to caffeine in control tissues but no inhibition in sensitized tissues. These results suggest the existence of differences in calcium movements in response to caffeine between control and sensitized tissues that may reflect abnormalities in calcium handling by the sensitized tissue.

Effect of dantrolene sodium in isolated guinea-pig trachea.

The effect of dantrolene sodium (3 microM-0.3 mM) on the spontaneous tone and responses to various contractile agonists was studied in isolated guinea-pig trachea. Dantrolene produced a concentration-related inhibition of the spontaneous tracheal tone, reaching a value of 94.8 +/- 4.8% of the relaxation induced by caffeine 10 mM. Removal of the epithelium did not affect the dantrolene-induced relaxation. Dantrolene did not alter the concentration-response curve for KCl and produced only small displacements of the concentration-response curves for CaCl2, acetylcholine and histamine, without affecting their maximal effects. Dantrolene dose relatedly inhibited the contraction induced by caffeine (1 mM) in Krebs solution containing indomethacin (2.8 microM) at 20 degrees C. The spasm induced by caffeine in Ca2(+)-free Krebs solution (20 degrees C, indomethacin 2.8 microM) was slightly depressed by dantrolene. Dantrolene did not depress the Ca2+ (1 microM)-induced contraction in skinned trachea. These results suggest that besides a possible intracellular site of action, the mechanism of the inhibitory effect of dantrolene in guinea-pig trachea may be related to interference with Ca2+ entry through pathways not susceptible to calcium channel blockers.

Modification by indomethacin of airway contractile responses in normal and sensitized guinea-pigs.

Active sensitization of guinea-pigs resulted in an increase in responsiveness and sensitivity of tracheal and lung parenchymal strips to CaCl2 (in K+-depolarised tissue), KCl, acetylcholine and histamine. Indomethacin (5 microM) preferentially enhanced the response of tracheal strips from normal animals to histamine and to a lesser extent acetylcholine but not to CaCl2 or KCl. A similar trend was observed in sensitized tissues. Indomethacin pretreatment did not cause changes in responsiveness or sensitivity of lung parenchymal strips from normal or sensitized guinea-pigs to the agonists tested. It is concluded that immunological sensitization produced a non-specific hyperresponsiveness in trachea and lung parenchymal strips. Conversely, cyclooxygenase inhibition by indomethacin elicited a selective increase in the responsiveness to certain agonists in central but not in the peripheral airways.

The relaxant effects of cromakalim (BRL 34915) on human isolated airway smooth muscle.

Cromakalim (BRL 34915) is a potassium channel opener with therapeutic potential as a bronchodilator in asthma. Cromakalim (0.1-30 mumol/l) inhibited the spontaneous tone of human isolated bronchi in a concentration-related manner being nearly as effective as isoprenaline or theophylline. The order of relaxant potencies (expressed as -log10 IC50 mol/l; mean +/- SEM) was isoprenaline (7.29 +/- 0.27; n = 8) > cromakalim (5.89 +/- 0.12; n = 7) > theophylline (4.07 +/- 0.13; n = 10). In human bronchi where tone had been raised by addition of histamine (0.1 mmol/l), acetylcholine (0.1 mmol/l) or leukotriene D4 (LTD4, 0.1 mumol/l), the relaxant effect of cromakalim was substantially reduced. Cromakalim suppressed the contraction produced by KCl (25 mmol/l) but not that produced by KCl (120 mmol/l). Tetraethylammonium (8 mmol/l) was without effect against the relaxant action of cromakalim but procaine (0.5-5 mmol/l) and glibenclamide (0.3 mumol/l) antagonised it. Cromakalim (10 mumol/l) produced an upward displacement of concentration-effect curves for KCl (1-100 mmol/l), acetylcholine (1 nmol/l-1 mmol/l) and histamine (1 nmol/l-1 mmol/l) but it did not alter the concentration-effect curve for LTD4 (0.1 nmol/l-0.1 mumol/l). When tissues were challenged in the presence of cromakalim (10 mumol/l) with KCl (100 mmol/l), acetylcholine (1 mmol/l) or histamine (1 mmol/l), an enhanced contraction was observed compared to control tissues. This enhancement by cromakalim was absent when tissues were challenged with acetylcholine or histamine in either a Ca(2+)-free medium (plus EGTA 0.1 mmol/l) or in the presence of verapamil (10 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of serotonin and calcium in normal and sensitized guinea pig isolated trachea.

Tracheal strips from normal and actively sensitized guinea pigs were studied to determine the responses to serotonin (5-hydroxytryptamine, 5-HT; 1 nM-0.1 mM) and ouabain (0.1 microM-0.1 mM), and the effects of increasing the extracellular calcium (Cao) concentration on tonic contractions elicited by 5-HT. Sensitized trachea exhibited an increased responsiveness and sensitivity to 5-HT and ouabain. Increases in Cao to achieve final concentrations of 5, 10 and 20 mM caused concentration-related relaxations of normal and sensitized tissues contracted to a similar plateau level with 5-HT. Inhibition of the Na+/K(+)-ATPase by ouabain (10 microM) reversed the effects of Cao from relaxation to contraction in normal and sensitized tissues contracted with 5HT. Sensitized preparations showed reduced relaxations in response to Cao (10-20 mM), and sensitized, ouabain-treated, trachea showed augmented contractions to Cao (10-20 mM) when compared to normal tissues. These results demonstrate a decreased membrane-stabilizing effect of Cao in sensitized trachea and the implication of the Na+/K(+)-ATPase in the regulation of membrane stability by Cao, suggesting a possible relevance to those mechanisms underlying airway hyperreactivity.

Cough reflex testing with inhaled capsaicin in the study of chronic cough.

OBJECTIVES: To assess the utility of capsaicin test in the differential diagnosis of non-productive causes of chronic cough and to examine the effects of treatment on this reflex. PARTICIPANTS: 86 healthy volunteers and 101 patients with chronic cough: asthma (n: 54) gastroesophageal reflux (n: 35) and post-nasal drip syndrome (n: 12). DESIGN: Prospective intervention trial. Spirometry, bronchoprovocation test with histamine (PC20), and cough challenge with ascending concentrations of capsaicin (0.49-500 microM) were initially performed in all subjects. Patients were treated for 3 months according to the origin of the cough. Concentrations that elicited two (C2) and five or more coughs (C5) were determined before and after treatment. RESULTS: In healthy subjects, cough sensitivity to capsaicin was not influenced by gender or smoking status; however, women with chronic cough were more sensitive to cough challenge than men. C2 and C5 were significantly lower in patients with asthma or gastroesophageal reflux than in post-nasal drip syndrome. No significant correlation was observed between the capsaicin cough threshold and PC20. Cough sensitivity did not improve significantly in most patients with asthma or gastroesophageal reflux despite adequate medical treatment during 3 months. Discriminative value of capsaicin test to differentiate healthy subjects from patients with asthma or reflux was poor. CONCLUSIONS: Cough sensitivity to inhaled capsaicin is a safe and reproducible tool in the study of chronic cough. However, its usefulness for the management and differential diagnosis is limited.

Noninvasive positive pressure home ventilation in restrictive disorders: outcome and impact on health-related quality of life.

Noninvasive positive-pressure home ventilation (NIPPHV) improves arterial blood gases, dyspnea and health-related quality of life (HRQL) in patients with restrictive thoracic diseases. Whether these changes persist during the follow-up remains unclear. The aim of this study was to investigate the long-term effects of NIPPHV upon dyspnea, HRQL, lung function and hospitalization rate in 35 patients with kyphoscoliosis and 27 individuals with several neuromuscular disorders. So, we measured dyspnea, HRQL, lung function and nocturnal oxygen saturation (SaO2) before and after 3, 6, 9, 12 and 18 months after NIPPHV. Dyspnea was assessed with the Borg scale and HRQL was measured using the Spanish validated version of the SF-36 questionnaire. The kyphoscoliosis group showed significant improvement of PaCO2 and SaO2 at 3 months and minor dyspnea changes at 6 months after NIPPHV had been started. These patients also showed improved health status in the following categories: "physical role" and "emotional role" at 3 months and in the categories "social functioning", "vitality" and "mental health" at 6 months after NIPPHV; some of these changes persisted at 9, 12 and 18 months. In the neuromuscular group, a significant improvement of SaO2 was observed at 3 months and this persisted for 18 months. Changes of HRQL in this group included a significant improvement in "physical role" at 3 months, "emotional role" and "social functioning" at 6 months and "physical functioning" at 9 months. The hospitalization rate decreased significantly in all patients from a mean annual admission rate of 1.1 (1.4) before NIPPHV to 0.6 (1.1) after 12 months of ventilatory support (P<0.005). We conclude that: (a) NIPPHV had a higher impact on arterial blood gases, dyspnea and health-related quality of life in patients with kyphoscoliosis than in those with neuromuscular disorders; (b) most clinical and functional changes persisted at long term and (c) a significant decrease in the hospitalization rate after NIPPHV occurred in both groups.

Different ability of trifluoperazine to inhibit agonist-induced contraction of lung parenchyma strips from control and sensitized guinea-pigs.

There is increasing interest in the therapeutic potential of calcium antagonists in asthma. Among them the use of calmodulin antagonists deserves consideration. In the present work the effect of trifluoperazine on contractions generated by different mechanisms (CaCl2, KCl, acetylcholine, histamine and 5-hydroxytryptamine) in lung parenchyma strip isolated from control and actively sensitized guinea-pigs has been studied. Trifluoperazine produced both in unsensitized and sensitized lung strips, a concentration-dependent, right, downward displacement of the concentration-response curves to the agonists used, although the sensitization procedure resulted in a potentiation in the ability of trifluoperazine to inhibit agonist-induced contractions. The basis for this greater potency of trifluoperazine in sensitized tissues remains to be elucidated but raises attention to the future use of selective calmodulin antagonists in the management of asthma.

Effects of alkylxanthines on contractility of diaphragm fibres isolated from normal and sensitized guinea-pigs.

This study investigates the effects of alkylxanthines on twitch tension generated by electrical stimulation (supramaximal pulses, 0.2 ms duration, 1 Hz) of diaphragm muscle fibres isolated from normal and actively-sensitized guinea-pigs. Caffeine, theophylline and theobromine increased, in a concentration-dependent manner (50-500 microM), twitch tension in normal and sensitized diaphragm. Caffeine (500 microM) enhanced contractility to a greater extent than theophylline or theobromine. Twitch potentiation by caffeine (500 microM) was significantly greater in sensitized diaphragm. Verapamil (0.1-100 microM) did not alter twitch contractions in the absence or presence of alkylxanthines in normal or sensitized strips. Dantrolene (0.01-100 microM) depressed, in a concentration-dependent fashion, twitch contractions of normal and sensitized diaphragm. The inhibitory concentration 50% (expressed as -log IC50) was 6.78 +/- 0.13 in normal tissues and 6.15 +/- 0.11 in sensitized tissues (n = 6 in each group; P < 0.05). Exposure to Ca(2+)-free, EGTA (0.1 mM)-containing medium, depressed twitch contraction of normal diaphragm to a lesser extent than that of sensitized diaphragm. Methylxanthines reversed depression of twitch contractions produced by exposure to dantrolene (5 microM) or a Ca(2+)-free medium. Adenosine (1-1000 microM) was without effect whereas enprofylline (50-500 microM) enhanced diaphragm contractility in normal tissues. This indicates that blockade of adenosine receptors is not involved in the inotropic effect of alkylxanthines in guinea-pig diaphragm. Results from this study suggest that alkylxanthines enhance diaphragm contractility in the guinea-pig by releasing intracellular Ca2+ and promoting extracellular Ca2+ entry through verapamil-insensitive pathways. An alteration of Ca2+ movements and stores may be present in the sensitized diaphragm.

Effects of phorbol 12,13-diacetate and its influence on spasmogenic responses in normal and sensitized guinea-pig trachea.

We have studied the effects of phorbol 12,13-diacetate (PDA) and its influence on a variety of spasmogenic responses in trachea isolated from normal and sensitized guinea-pigs. Tracheal preparations were denuded of epithelium, treated with indomethacin (2.8 microM), and cooled to 20 degrees C. In these experimental conditions, tracheal strips contracted to PDA (0.1 nM-1 microM). Contractions to PDA (1 microM) were greater in sensitized tissues. In normal trachea, contractions to PDA (0.1 microM) were depressed by H-7, 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine, (50 microM), amiloride (10 microM), verapamil (10 microM) and Ca(2+)-free exposure. Similar effects were obtained in sensitized trachea except that PDA-induced contraction was resistant to verapamil and Ca(2+)-free exposure. Cooling (20 degrees C) of normal trachea substantially depressed the response to CaCl2 (in K(+)-depolarized tissues), KCl, histamine and 5-hydroxytryptamine without affecting the spasm induced by acetylcholine. This inhibitory effect of cooling was not observed in sensitized trachea. PDA (0.1 microM) did not affect spasmogenic responses at 37 degrees C but counteracted the inhibitory effect of cooling in normal trachea. PDA had no effect on sensitized tissues. PDA (0.1-1 microM) did not alter Ca(2+)-induced contraction of skinned normal and sensitized trachea. These results support the hypothesis that intracellularly stored Ca2+ plays an important role in the activation of sensitized tracheal muscle.

Non-specific hyperreactivity to pharmacological stimuli in tracheal and lung parenchymal strips of actively sensitized guinea-pigs.

The responsiveness of tracheal and lung parenchymal strips isolated from actively sensitized guinea-pigs to CaCl2 (in K+-depolarized tissue), KCl, acetylcholine and histamine was compared with that of strips from unsensitized animals. The concentration-response curves to the mentioned agonists exhibited, in the sensitized group, a left upward displacement (greater maximal effect, lesser effective concentration 50% and a steeper slope) compared with those obtained in the unsensitized group. These results indicate the existence of a non-specific increase in responsiveness in the airway smooth muscle from sensitized animals.