Effects of several glucocorticosteroids and PDE4 inhibitors on increases in total lung eosinophil peroxidase (EPO) levels following either systemic or intratracheal administration in sephadex- or ovalbumin-induced inflammatory models.

Representative glucocorticosteroids (GCS) and phosphodiesterase IV (PDE4) inhibitors were compared in several models of pulmonary inflammation ranging in severity. Lung tissue eosinophil peroxidase (EPO) levels rather than bronchoalveolar lavage fluid (BALF) EPO or eosinophil percentages were used to indicate eosinophil recruitment after intratracheal instillation of sephadex beads in rats or nebulized ovalbumin in sensitized guinea pigs. A single oral or intratracheal administration of a GCS was effective against mild and robust sephadex-induced eosinophilia whereas the PDE4 inhibitors evaluated appeared more effective in the milder sephadex models. The GCS were also more effective against sephadex-induced than ovalbumin-induced eosinophilia. The effectiveness of the GCS and PDE4 inhibitors improved when the severity of the ovalbumin-induced eosinophilia was decreased. Multiple day dosing also improved activity. These studies indicated that activity was influenced greatly by administration protocols, the severity of the inflammatory response and possibly the method used for estimating eosinophil recruitment.

Guinea pig pulmonary mechanics: altered sensitivity to carbachol by cadmium and/or selenium.

Male Hartley guinea pigs (480-610 g) were treated intratracheally as follows: saline, cadmium (Cd, 0.3 mg), selenium (Se, 0.3 or 0.06 mg), or Se (0.06 mg) and Cd (0.3 mg) simultaneously. Selenium and Cd were administered as sodium selenite and cadmium chloride, respectively. Twenty-four h later, dynamic lung compliance (Cdyn) and pulmonary resistance (Rp) were measured before (baseline Cdyn and Rp) and after carbachol administration (0.0001, 0.001, 0.01, and 0.1 mumol/kg, intravenously). Results indicated a significant decrease in baseline Cdyn caused by 0.3 mg of Cd, 0.3 mg or 0.06 mg of Se, and 0.3 mg of Cd with 0.06 mg of Se (p < 0.05). A significant increase in baseline Rp due to 0.3 mg of Se was observed (p < 0.05). Carbachol decreased Cdyn significantly below baseline, evident after lower doses of carbachol, in guinea pigs pretreated with 0.3 mg of Se, whereas a significant improvement in Cdyn was seen after 0.0001 mumol/kg carbachol in the group pretreated with Se and Cd simultaneously (p < 0.05) compared with the respective baseline values of the saline-treated group. Similarly, a significant increase in Rp was observed after carbachol in groups pretreated with 0.3 mg of Cd or Se (p < 0.05). Results also indicated a significant increase in large airway constriction caused by Cd and/or Se (p < 0.05). A leftward shift in the carbachol dose-response curve indicated increased sensitivity to carbachol in Cd- and/or Sepretreated guinea pigs.

Cadmium and/or selenium effects on guinea pig lung PGE2, TXB2 and LTC4.

Male Hartley guinea pigs (480-610 g; n=5) were treated intratracheally with saline, cadmium (Cd, 0.3 mg) as cadmium chloride, selenium (Se, 0.3 or 0.06 mg) as sodium selenite or Se (0.06 mg) and Cd (0.3 mg). After 24 hours, lungs were collected and analyzed for prostaglandin (PGE2), thromboxane (TXB2) and leukotriene (LTC4) levels. Results indicated that, 0.3 mg Se and 0.06 mg Se in combination with 0.3 mg Cd increased PGE2 significantly. Selenium and Cd alone or in combination, decreased LTC4 and TXB2 significantly.

The equivalent bronchodilator effects of salbutamol formulated in chlorofluorocarbon and hydrofluoroalkane-134a metered dose inhalers on the histamine-induced pulmonary response in dogs.

PURPOSE: The bronchodilator effect of salbutamol formulated in hydrofluoroalkane-134a (HFA-134a), a chlorofluorocarbon (CFC)-free propellant for metered dose inhalation (MDI) devices, was compared with that of salbutamol formulated in CFC in anesthetized dogs. METHODS: Bronchospasms were induced by the intravenous injection of histamine, and bronchial resistance was measured by the method of Konzett and Rossler. RESULTS: While the placebo vehicles (HFA-134a and CFC propellants) had no significant effect on histamine-induced bronchospasms, the salbutamol/HFA-134a and salbutamol/CFC MDI formulations had equivalent dose-related inhibitory effects. CONCLUSIONS: These data indicated that salbutamol formulated in HFA-134a and that in CFC propellant are bioequivalent.

Selenium and cadmium induced pulmonary functional impairment and cytotoxicity.

Ovalbumin-sensitized (50 mg/kg, i.p.) male Hartley-guinea-pigs (550-610 g; n = 6) were treated 14 days later intratracheally with saline, cadmium (Cd 0.3 mg), selenium (Se 0.3 mg or 0.06 mg) or Se (0.06 mg) with Cd (0.3 mg). After 24 h, baseline dynamic-lung-compliance (Cdynl) and pulmonary-resistance (Rp), and percent change after ovalbumin-aerosol-challenge (10 mg/ml, 60 s) were assessed. Cadmium or Se (0.3 mg), Se (0.06 mg) and/or Cd (0.3 mg) decreased Cdynl (P < 0.05). Selenium (0.3 mg) increased Rp (P < 0.05). Ovalbumin-challenge decreased Cdynl and increased Rp in all groups. Analysis of bronchoalveolar-lavage-fluid (BALF) displayed increased activities of lactate-dehydrogenase (LDH), beta-glucuronidase (beta-G), alkaline-phosphatase (AP), and protein due to 0.3 mg Se, 0.3 mg Cd alone or with 0.06 mg Se (P < 0.05). Findings indicated that, 0.3 mg Se is more detrimental than 0.3 mg Cd to lung-dynamics despite a modest protection by 0.06 mg Se against Cd illustrated by an ameliorated Cdynl and lower protein in BALF.

Presence of immunocytes and sulfidopeptide leukotrienes in the inflamed guinea pig distal colon.

This study examined whether the immunocyte recruitment associated with a mild inflammatory state induced by acetic acid would produce detectable sulfidopeptide leukotriene (LT) levels from colonic tissues or in dialysates. Histological examination and measurements of peroxidase activities of inflamed tissues indicated edema, hyperplasia and neutrophil infiltration. Significant elevated LTB4 and prostaglandin E2(PGE2) levels were found but only slight elevations in sulfidopeptide LTs occurred. A slight elevation in eosinophil peroxidase indicated that eosinophil infiltration also occurred. The increase in sulfidopeptide LT levels appeared insufficient by itself to alter secretory responses in the distal colon. However, combined with other immunocyte products such as PGs, the sulfidopeptide LTs may influence the symptomology of inflammatory bowel disease.

Selective hyperresponsiveness to ovalbumin-induced epithelial transport in inflamed guinea pig distal colon.

This study examined whether a mild inflammatory state induced by acetic acid would alter ovalbumin-induced motor and secretory responses of the actively sensitized colon. Short-circuit current (Isc), a measure of active transepithelial ion transport, and longitudinal contractility were measured, respectively, in mucosa-submucosa or smooth muscle sheets from guinea pig distal colon. Ovalbumin produced similar, concentration-dependent increases in Isc in noninflamed and inflamed colonic mucosa. Chlorpheniramine, an H1-histamine antagonist, produced a concentration-related decrease in antigen efficacy that was greater in noninflamed mucosa than in inflamed tissues. Lipoxygenase inhibitors (R840 and A64077) were equally effective in decreasing ovalbumin-induced secretion in both inflamed and noninflamed tissues. Ovalbumin also produced longitudinal muscle contractions that were of similar magnitude in inflamed and noninflamed strips. Moreover, chlorpheniramine and lipoxygenase inhibitors inhibited contractile responses in muscle from both inflamed and noninflamed colons. These results suggest that inflammation produces hyperresponsiveness in the colonic mucosa but not in the underlying longitudinal smooth muscle.

Neurally mediated actions of leukotrienes on ion transport in guinea pig distal colon.

The effects of the sulfidopeptide leukotrienes (LT), LTC4, LTD4 and LTE4 on short-circuit current (Isc), a measure of active ion transport, were determined in muscle-stripped mucosa sheets from the guinea pig distal colon. LTC4 and D4, but not E4, evoked concentration-dependent increases in Isc. Auto- and cross-tachyphylaxis could be demonstrated in LT actions. LTD4 was more sensitive than LTC4 to inhibition by the LTD4 antagonist, 1-<2-hydroxy-3-propyl-4-<4-(1H-tetrazol-5-yl)butoxy>phenyl>etha none, and the intracellular Ca++ inhibitor, 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester. Mucosal LT effects were reduced in tissues pretreated with bumetanide or bathed in HCO3(-)-free media. Measurements of transepithelial Na+ and Cl- fluxes revealed that LTC4 increased unidirectional and net secretory fluxes of Cl- but had no effect on Na+ transport. Tetrodotoxin, atropine and indomethacin inhibited mucosal responses to LTC4 and D4; in addition prazosin inhibited LTD4 effects. The results suggest that LTC4 and D4 evoke anion secretion by acting through distinct LT receptor populations. These effects are mediated in part by cholinergic and adrenergic submucosal neurons as well as by colonic prostanoids.

Bronchodilator and other pharmacological activities of R-836 (2,5-diethyl-7-(4-thiomorpholino)-1,2,4-triazolo[1,5-c]pyrimidin e).

The bronchodilator activity of R-386 (2,5-diethyl-7-(4-thiomorpholino)-1,2,4-triazolo[1,5-c]pyrimidine) was demonstrated in isolated guinea-pig tracheal preparations and in vivo in dogs, guinea-pigs and rats. Guinea-pig tracheal preparations contracted by histamine, acetylcholine, BaCl2, leukotriene C4 or antigen were relaxed 50% by concentrations (IC-50 values) of R-836 of approximately 0.3 microgram/ml (10(-6) M) in all cases. In the conscious guinea-pig, oral or i.p. administration of R-836 prevented asphyxial collapse, death or dyspneic changes produced by histamine, antigen of LTC4. In anesthetized guinea-pigs, R-836 reduced bronchoconstriction produced by antigen or PAF (Konzett-Rössler preparation). In the dog, i.v. or intraduodenal administration of R-836 reduced bronchoconstriction produced by methacholine or histamine. In the rat, i.p. administration of R-836 reduced bronchoconstriction produced by 5-HT or antigenic challenge. In these in vivo models, when direct comparisons were made, R-836 was estimated to possess 2 to 3 times the potency of theophylline. R-836, at doses 80 times those necessary to produce bronchodilation, had no effect on blood pressure or heart rate of guinea-pigs. R-836 was not a CNS stimulant in mice, was not diuretic in rats, only marginally inhibited adenosine-induced responses in mice and guinea-pigs and was a weak inhibitor of phosphodiesterase in vitro.

Use of a simple in vivo technique to investigate components of the immediate hypersensitivity reaction in conscious guinea pigs.

A semiplethysmographic method was used to delineate the effects of aerosol antigen challenge on the respiratory pattern of conscious, sensitized guinea pigs. Chlorpheniramine pretreatment prevented death, delayed the onset of respiratory symptoms and decreased the severity of the hypersensitivity reaction. This reaction could be further diminished to varying degrees by the addition of FPL55712, atropine sulfate and/or imidazole to chlorpheniramine. Indomethacin and nordihydroguaiaretic acid (NDGA) with chlorpheniramine caused a potentiation in the severity of the hypersensitivity reaction. However, chlorpheniramine, NDGA and imidazole in combination blocked the hypersensitivity reaction. The technique appears to demonstrate the involvement of several suggested mediators in asthma and appears potentially useful as an indicator of effects on arachidonic acid metabolism and metabolites.

The reinforcing properties of procaine and d-amphetamine compared in rhesus monkeys.

Twelve rhesus monkeys were studied under a fixed-ratio (FR) schedule of intravenous procaine or d-amphetamine injection from 8 A.M. to 4 P.M. daily. Under the FR schedule, every nth lever press produced an injection. The FR value (n) and the dose per injection of procaine and d-amphetamine were varied systematically. At a FR value of 10, responding was maintained by doses of procaine ranging from 0.125 to 12 mg/kg/injection and by doses of d-amphetamine ranging from 0.01 to 0.1 mg/kg/injection. At doses of 1 mg/kg/injection of procaine and 0.1 mg/kg/injection of d-amphetamine, responding was maintained at FR values up to 100 by procaine and d-amphetamine but not by saline. Responding and drug intake were relatively constant throughout each 8-hour session with procaine, but responding tended to decrease and was more variable over the session with d-amphetamine. No toxic effects were observed in doses up to 6 mg/kg/injection with procaine. At this dose, eating and drinking ceased during the period of access to the drug. One of the four monkeys died at 8 mg/kg/injection of procaine. At 12 mg/kg/injection all three monkeys tested showed signs of toxicity.