Pulmonary edema of environmental origin

The gasotransmitter hydrogen sulphide decreases Na⁺ transport across pulmonary epithelial cells

BACKGROUND AND PURPOSE The transepithelial absorption of Na(+) in the lungs is crucial for the maintenance of the volume and composition of epithelial lining fluid. The regulation of Na(+) transport is essential, because hypo- or hyperabsorption of Na(+) is associated with lung diseases such as pulmonary oedema or cystic fibrosis. This study investigated the effects of the gaseous signalling molecule hydrogen sulphide (H(2) S) on Na(+) absorption across pulmonary epithelial cells. EXPERIMENTAL APPROACH Ion transport processes were electrophysiologically assessed in Ussing chambers on H441 cells grown on permeable supports at air/liquid interface and on native tracheal preparations of pigs and mice. The effects of H(2)S were further investigated on Na(+) channels expressed in Xenopus oocytes and Na(+) /K(+)-ATPase activity in vitro. Membrane abundance of Na(+) /K(+)-ATPase was determined by surface biotinylation and Western blot. Cellular ATP concentrations were measured colorimetrically, and cytosolic Ca(2+) concentrations were measured with Fura-2. KEY RESULTS H(2)S rapidly and reversibly inhibited Na(+) transport in all the models employed. H(2)S had no effect on Na(+) channels, whereas it decreased Na(+) /K(+)-ATPase currents. H(2)S did not affect the membrane abundance of Na(+) /K(+)-ATPase, its metabolic or calcium-dependent regulation, or its direct activity. However, H(2)S inhibited basolateral calcium-dependent K(+) channels, which consequently decreased Na(+) absorption by H441 monolayers. CONCLUSIONS AND IMPLICATIONS H(2) S impairs pulmonary transepithelial Na(+) absorption, mainly by inhibiting basolateral Ca(2+)-dependent K(+) channels. These data suggest that the H(2)S signalling system might represent a novel pharmacological target for modifying pulmonary transepithelial Na(+) transport.

Gasotransmitters: novel regulators of epithelial na(+) transport?

The vectorial transport of Na(+) across epithelia is crucial for the maintenance of Na(+) and water homeostasis in organs such as the kidneys, lung, or intestine. Dysregulated Na(+) transport processes are associated with various human diseases such as hypertension, the salt-wasting syndrome pseudohypoaldosteronism type 1, pulmonary edema, cystic fibrosis, or intestinal disorders, which indicate that a precise regulation of epithelial Na(+) transport is essential. Novel regulatory signaling molecules are gasotransmitters. There are currently three known gasotransmitters: nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H(2)S). These molecules are endogenously produced in mammalian cells by specific enzymes and have been shown to regulate various physiological processes. There is a growing body of evidence which indicates that gasotransmitters may also regulate Na(+) transport across epithelia. This review will summarize the available data concerning NO, CO, and H(2)S dependent regulation of epithelial Na(+) transport processes and will discuss whether or not these mediators can be considered as true physiological regulators of epithelial Na(+) transport biology.

A literature review: therapy for phosgene poisoning

A literature search designed to collect information on therapy for phosgene poisoning has been conducted for the period 1920-1982. To achieve this goal, literature services were consulted, cross references were carefully followed and, whenever possible, unpublished reports (e.g., from Edgewood Arsenal and Porton Research Station) were evaluated. The various therapeutic agents and measures described in the literature are presented in alphabetical order. When available, detailed data are given for the phosgene dose, interval of time between exposure and institution of therapy, therapeutic effect and parameters used to assess efficacy. A final summary presents general recommendations for therapy and for further research.

Prophylactic and antidotal effects of hexamethylenetetramine against phosgene poisoning in rabbits

New Zealand white rabbits were exposed to phosgene doses, expressed as Ct factors, of 125-3120 ppm X min. Hexamethylenetetramine (HMT), 0.3 gm/kg as a 40% aqueous solution, was injected via an ear vein into separate groups of animals at 5-10 min pre-exposure or at 15 min post-exposure to the gas. Non-exposed and exposed, non-HMT-treated animals served as controls. As assessed by survival times, gross morphology of the lungs, percent lung water measurements, serum LDH values, and respiratory gas parameters, pre-exposure administration of HMT at Ct factors as high as 3120 ppm X min provided significant prophylaxis against the effects of phosgene. Post-exposure administration of HMT, however, provided no antidotal effect even when administered as soon as 15 min after exposure to 125 ppm X min phosgene.

A critical review of the literature on hydrogen sulfide toxicity

The information available on the biological activity of hydrogen sulfide has been examined for present status of critical results pertaining to the toxicity of hydrogen sulfide. This review of the literature is intended as an evaluative report rather than an annotated bibliography of all the source material examined on hydrogen sulfide. The information was selected as it might relate to potential toxic effects of hydrogen sulfide to man and summarized, noting information gaps that may require further investigation. Several recommendations are listed for possible consideration for either toxicological research or additional short- and long-term tests. Two bibliographies have been provided to assist in locating references considered in this report: (1) literature examined but not cited and (2) reference citations. The majority of the references in the first bibliography were considered peripheral information and less appropriate for inclusion in this report.

The methenamine misunderstanding in the therapy of phosgene poisoning

A thorough analysis of the pertinent literature leads to the conclusion that there is no justification for the use of methenamine (hexamethylene tetramin, Urotropin) for the therapy of phosgene poisoning.

Acute chlorine gas exposure

The heavy use of chlorine gas in industry and water purification poses the constant threat of mass gas exposure. In a recent experience with a chlorine gas disaster involving over 100 patients, 64, including six subsequently requiring admission, were treated in the main emergency unit facility. The remainder were triaged to a safe area away from the emergency unit with instructions for symptomatic treatment. Injuries were limited to four organ systems: pulmonary, gastrointestinal, ophthalmic, and cutaneous. Current treatment methods are compared with those in the literature and a protocol for management provided.

Acute pulmonary edema following intravenous fluorescein angiography

A 64-year-old white man with no history of cardiac or bronchopulmonary disease developed acute pulmonary edema shortly after undergoing diagnostic intravenous fluorescein angiography. The patient responded quickly to a course of oxygen, positive pressure breathing, diuretics, and sedation.