The diseased lung and drugs

Prostanoids Secreted by Alveolar Macrophages Enhance Ionic Currents in Swine Tracheal Submucosal Gland Cells

We examined the effect of substances released by swine alveolar macrophages (AMs) on ionic currents in airway submucosal gland cells (SGCs). AMs obtained by lavage were activated by 24-h zymosan exposure (0.1 mg/ml). Supernatant was collected and used to stimulate short-circuit current changes (DeltaI(SC)) in SGC monolayers in Ussing chambers. Dexamethasone (1 microM) or indomethacin (5 muM) during zymosan exposure of AMs reduced or abolished the supernatant-induced DeltaI(SC). Zymosan exposure induced a 5-fold increase in cyclooxygenase (COX)-2 but not COX-1 protein levels in AMs. Prostaglandin E(2) (PGE(2)) concentration in the supernatant from zymosan-activated AMs was 550 +/- 10 nM (n = 3) compared with 28 +/- 3 nM for unstimulated AMs (n = 3). PGE(2), applied serosally, induced DeltaI(SC) with an EC(50) of 15.5 +/- 1.3 nM (n = 4) and 3.6 +/- 1.8 microM (n = 3) when applied apically. Four types of endoprostanoid receptors (EP(1-4)) were detected in SGCs using Western blot. PGE(2)-induced DeltaI(SC) were inhibited by AH6809 (6-isopropoxy-9-oxoxanthene-2-carboxylic acid) but not by SC19220 (8-chloro-dibenzo[b,f][1,4]oxazepine-10(11H)-carboxylic acid, 2-acetylhydrazide), suggesting that endoprostanoid (EP)(2) but not EP(1) receptors were activated by PGE(2). Pretreatment of SGCs with supernatant from zymosan-activated AMs, PGE(2), or forskolin enhanced the sensitivity to acetylcholine (ACh)-induced DeltaI(SC). PGE(2)-induced DeltaI(SC) were blocked by charybdotoxin (ChTX), chromanol 293B, or glibenclamide. ACh-induced DeltaI(SC) were only blocked by ChTX or glibenclamide. None of these blockers altered PGE(2) pretreatment-induced sensitization of ACh-induced DeltaI(SC). These results demonstrate that prostanoids released from activated AMs directly increase cystic fibrosis transmembrane conductance regulator and K(+) channel activity. ACh-induced DeltaI(SC) are also enhanced due to enhanced activation of Ca(2+)-activated K(+) channels (K(Ca)).

Role of the lung in accumulation and metabolism of xenobiotic compounds--implications for chemically induced toxicity

The mammalian lung is exposed to and affected by many airborne and bloodborne foreign compounds. This review summarizes the role of lung in accumulation and metabolism of xenobiotics, some of which are spontaneously reactive or are metabolically activated to toxic intermediates. The specific architectural arrangement of mammalian lung favors that so-called pneumophilic drugs are filtered out of the blood and are retained within the tissue as shown in particular for amphetamine, chlorphentermine, amiodarone, imipramine, chlorpromazine, propranolol, local anaesthetics, and some miscellaneous therapeutics. There is strong evidence that intrapulmonary distribution activity and regulation of drug-metabolizing enzymes in lung is distinct from liver. This review focuses on the metabolic rate of selected compounds in lung such as 5-fluoro-2'-deoxyuridine, local anesthetics, nicotine, benzo(alpha)pyrene, ipomeanol, 4-methylnitrosamino-1-(3-pyridyl)-1-butanone. It is widely accepted that the formation of radical species is a key event in the pneumotoxic mechanisms induced by bleomycin, paraquat, 3-methylindole, butylhydroxytoluene, or nitrofurantoin. Finally, methodological approaches to assess the capacity of lung to eliminate foreign compounds as well as biochemical features of the pulmonary tissue are evaluated briefly.

Chemical-induced autoimmune reactions and Spanish toxic oil syndrome. Focus on hydantoins and related compounds

Autoimmune diseases comprise a wide spectrum of overlapping, systemic and organ-specific disorders. Although, etiology and pathogenesis of such disorders are largely unknown, endogenous host factors and exogenous agents, such as viruses, bacteria, and small molecular weight chemicals, drugs and food components, are believed to be involved. The toxicological significance of low molecular weight compounds on induction of autoimmune disorders is illustrated by the toxic oil syndrome (TOS), a chemically induced epidemic, observed in Spain since 1981. The causative chemical(s) of TOS is still elusive, but an association between ingestion of refined aniline-adulterated rapeseed oil and the syndrome is well-documented. Epidemiological, clinical and immunopathological symptoms of TOS are briefly reviewed. The striking resemblance with immunological disorders, observed in man upon medication with hydantoins and related compounds, is demonstrated. The likeliness of formation of a hydantoin-related compound in the aniline-adulterated oil is evidenced and its role as possible toxic agent in TOS is proposed. Further, the presence of hydantoins and related compounds in food is briefly reviewed and it is suggested that these chemicals may account for a portion of idiopathic autoimmune diseases observed in man. The need for development of animal models to assess this kind of immunotoxicological effects is stressed.