alpha-naphthyl-thiourea and Lung-Diseases

Oxidative injury to the pulmonary endothelium plays and important role in lung pathology. Oxidants (that accumulate in lung tissue upon hyperoxia or hypoxia, or are released from activated leukocytes) can destroy endothelial cells. Investigation of the mechanisms of oxidative endothelial injury and the choice of valid criteria with which to measure these pathological deviations are therefore of great importance. Among the criteria used to assess endothelial injury (e.g. accumulation of the products of lipid peroxidation, enhancement of pulmonary microvascular permeability, morphological changes), monitoring of angiotensin-converting enzyme (ACE) is of great interest because it is associated with the endothelial surface and thus reflects endothelial status. Assessment of lung rather than serum ACE activity is the best indicator of endothelial injury. For a comprehensive evaluation of endothelial status, not only total ACE activity in lung tissue but also ACE accessibility to circulating ligands should be monitored. Radiolabelled ACE substrates have been used as ligands in the perfusion of isolated lungs of experimental animals. Radiolabelled monoclonal antibody (Mab) to ACE has been proposed as an alternative ligand, because a drastic decrease in uptake of this Mab by the lungs upon lung injury has been shown. This approach is extremely sensitive: a decrease in antibody uptake occurs even upon mild (nonoedematous) oxidative lung injury, when other indicators, such as lung and serum ACE activity, accumulation of the products of lipid peroxidation, and microvascular permeability, remain unchanged. The use of radiolabelled Mab allows the pulmonary microvascular status to be monitored by gamma-scintigraphy.

Topics: Biomarkers; Endothelium; Humans; Immunoglobulin G; Lipid Peroxidation; Lung; Lung Diseases; Oxygen; Peptidyl-Dipeptidase A; Thiourea

Topics: Air Pollutants; Animals; Bleomycin; Carbon Tetrachloride; Carbon Tetrachloride Poisoning; DNA; Dogs; Free Radicals; Haplorhini; Humans; Hydrogen Peroxide; In Vitro Techniques; Lipid Peroxides; Lung; Lung Diseases; Mice; NADP; Nitrofurantoin; Nitrous Oxide; Oxidation-Reduction; Ozone; Paraquat; Rats; Superoxides; Thiourea

The rodenticide alpha-naphthylthiourea (ANTU) causes pulmonary edema and pleural effusion that leads to death via pulmonary insufficiency. Rats become resistant to the lethal effect of ANTU if they are first exposed to a small, nonlethal dose of ANTU. Young rats are also resistant to ANTU. The mechanism by which rats develop resistance by a prior, small dose exposure has yet to be determined. Growth factor induced-pulmonary hyperplasia has been demonstrated to attenuate ANTU-induced lung leak. We hypothesized that a small dose of ANTU protects against a large dose through pulmonary cell hyperplasia induced by the protective dose. Furthermore, we hypothesized that this hyperplasia is associated with altered transcription of growth factors. Male Sprague-Dawley rats (175-225 g) were treated with a low dose of ANTU (5 mg ANTU/kg; ANTU(L)) 24 h before challenge with a 100% lethal dose of ANTU (70 mg ANTU/kg; ANTU(H)) resulting in 100% protection against the lethal effect of ANTU(H). ANTU(L) protection against ANTU(H) lasted for 5 days, slowly phased out, all being lost by day 20. Injury was assessed by estimating pulmonary vascular permeability and through histopathological examination. ANTU(H) alone resulted in an increase in pulmonary edema leading to animal death. However, injury was prevented if the rats were first treated with ANTU(L). There was a stimulation of pulmonary cell hyperplasia in the lungs of ANTU(L) treated rats as measured by [3H]-thymidine and bromodeoxyuridine incorporation. Treatment with the antimitotic agent colchicine abolished ANTU(L)-induced resistance to ANTU(H). ANTU resistant rats were also resistant to the lethal effect of paraquat. Paraquat is not taken up by pneumocytes if they are undergoing hyperplasia. ANTU(L) administration resulted in an up regulation of gene transcription for keratinocyte growth factor, transforming growth factor-beta, keratinocyte growth factor receptor and epidermal growth factor receptor as determined through reverse transcription-polymerase chain reaction. A significant increase in transforming growth factor-alpha was not observed. These findings collectively suggest that ANTU(L)-induced pulmonary cell hyperplasia underlies resistance to ANTU(H). Furthermore, the stimulation of hyperplasia may be due to altered growth factor and growth factor receptor expressions.

Topics: Animals; Capillary Permeability; Cell Nucleus; Colchicine; Drug Resistance; Herbicides; Hyperplasia; Lung Diseases; Male; Mitosis; Paraquat; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; Rodenticides; Thiourea; Thymidine; Time Factors

Administration of alpha-naphthylthiourea (ANTU) to rats causes damage to pulmonary endothelial cells and possibly mesothelial lining cells that together may account for the massive pleural effusion characteristic of thiourea toxicity. Using 35S-thiourea as a model compound, the extent of binding of 35S to lung proteins correlated well with the extent of edema, suggesting that the extent of binding of thiourea metabolites is a measure of lung toxicity. ANTU and phenylthiourea (PTU) compete for 35S binding to lung slices, suggesting that these toxins may act in a similar way. Binding of 35S in lung slices from resistant rats is much less than in controls, and resistance cannot be explained by differences in either whole body metabolism or redistribution of thiourea in vivo. Lung glutathione levels (in vitro and in vivo) in normal and resistant rats following thiourea administration were essentially the same. However, at doses of thiourea that cause pleural effusion, there was an increase in total lung glutathione.

Topics: Animals; Binding, Competitive; Drug Resistance; Endothelium; Glutathione; Lung Diseases; Mesoderm; Protein Binding; Rats; Rodenticides; Thiourea

To study the value of indexes of endothelial cell function in experimentally induced pulmonary microvascular injury, lung damage was produced in anesthetized dogs by intravenous injection of oleic acid (OA; n = 6), alpha-naphthylthiourea (ANTU; n = 5), or phorbol myristate acetate (PMA; n = 6). Angiotensin-converting enzyme (ACE) activity in serum and simultaneous measurements of serotonin (SER) and propranolol (PROP) pulmonary extraction along with several physiologic parameters were determined and compared with those obtained in a control group (n = 5) before and then at 2-h intervals for 8 h after administration of the toxic agent. ACE activity in serum showed a sustained and significant increase in the PMA and OA groups throughout the whole study period, whereas it decreased significantly at 4 h in the ANTU group. SER pulmonary uptake decreased significantly, but slightly, only in the PMA group at 8 h (-5%). At 6 and 8 h respectively, PROP extraction dropped significantly in the PMA (-11 and -13%) and OA (-13 and -19%) groups. This decrease in PROP extraction was likely to result from physiologic changes due to the development of pulmonary edema as suggested by the correlation between the changes in amine uptake and those affecting pulmonary artery pressure and total static respiratory compliance. The lack of effects on SER uptake by the lungs under these experimental conditions indicate that dissociation exists between metabolic dysfunction of pulmonary endothelial cells and fluid leakage.

Topics: Anesthesia; Animals; Blood Pressure; Dogs; Endothelium, Vascular; Lung; Lung Diseases; Microcirculation; Oleic Acid; Oleic Acids; Peptidyl-Dipeptidase A; Propranolol; Pulmonary Circulation; Serotonin; Tetradecanoylphorbol Acetate; Thiourea; Vascular Diseases; Vascular Resistance

1. The hydrolysis of adenosine di- and monophosphate (ADP, AMP) was studied in perfused lungs isolated from rats treated with alpha-naphthylthiourea (ANTU) to induce acute lung injury. This injury is associated with damage to the endothelium, the locus of the ADP and AMP hydrolysing enzymes. 2. Treatment with ANTU did not change the proportion of [3H]-ADP surviving a single passage through the pulmonary circulation, at any time up to 50 h after ANTU. Less than 8% and 2% respectively of 1 or 0.1 mumol ADP, given as a bolus, appeared in lung effluent. 3. The metabolites of ADP, AMP and adenosine in lung effluent were increased fro 2 h after ANTU. 4. Metabolism of [3H]-AMP as substrate was always low but, following ANTU treatment, the adenosine content of lung effluent increased four fold. 5. It appears that, in spite of considerable endothelial cell damage, as demonstrated by pulmonary oedema, the ectoenzymes catalysing ADP and AMP hydrolysis were relatively little affected by ANTU.

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Monophosphate; Animals; Chromatography, Ion Exchange; Chromatography, Thin Layer; In Vitro Techniques; Lung; Lung Diseases; Male; Organ Size; Perfusion; Rats; Rodenticides; Thiourea; Time Factors

The reasons for greater lung vascular permeability to anionic macromolecules are not understood. In order to determine whether the luminal or abluminal surfaces of lung capillary endothelial cells differ with respect to surface charge, we compared the binding of cationic ferritin, an electron dense probe, with these cell surfaces in lung capillaries. Because lung capillaries are not normally permeable to cationic ferritin, lungs were examined from rats with increased permeability edema caused by pretreatment with alpha-naphthylthiourea (ANTU). We found that more cationic ferritin particles bound to the luminal than to the abluminal surfaces of lung capillary endothelium. In order to determine whether this was due to inaccessibility of cationic ferritin to the lung interstitium, we also compared cationic ferritin binding to the apical and basal surfaces of bovine calf aortic and main pulmonary arterial endothelial cells in tissue culture. We found that more cationic ferritin bound to the apical than to the basal surface of the cultured cells. The binding of cationic ferritin to cultured endothelial cells was due to charge since native, anionic ferritin did not bind to either surface and binding was decreased by neuraminidase pretreatment of cultures. Cultures incubated with thiourea, another thiocarbamide that causes increased permeability edema in vivo, also showed greater binding of cationic ferritin to the apical cell surface, suggesting that the differences seen in vivo were not due to thiocarbamide injury. However, another cationic probe, ruthenium red, bound to both the apical and basal surfaces of cultured endothelial cells. These results suggest that the basal endothelial cell surface does not lack anionic sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Capillaries; Culture Techniques; Endothelium; Ferritins; Lung Diseases; Male; Perfusion; Pulmonary Circulation; Rats; Rats, Inbred Strains; Ruthenium; Ruthenium Red; Thiourea

Recent work with isolated blood vessels has emphasized the importance of intact endothelium when the relaxation of vascular smooth muscle is induced by acetylcholine (ACh). However, the physiologic significance of this endothelial-dependent ACh response in a complete organ circulation is unclear. We questioned whether diminished ACh vasodilation would result from damage of lung vascular endothelium and whether this response could be used as an indication of endothelial injury. We therefore induced pulmonary endothelial cell injury in one rat model by repeated injections of alpha-naphthyl thiourea (ANTU) and in a second rat model by exposing rats for 52 h to 100% oxygen at a barometric pressure of 760 torr (hyperoxia). Rats injected with Tween 80, the solvent for ANTU, or exposed to ambient Denver air served as the respective control animals. The isolated lungs of these rats were perfused with a recirculating cell- and plasma-free, physiological salt solution to study the effect of ACh or NaCl infusion on pulmonary perfusion pressure and vascular responsiveness. ANTU-treated rats demonstrated an intact vasodilatory response after ACh infusion when compared with the solvent control animals. The immediate pulmonary vasodilation after ACh infusion was slightly enhanced in the hyperoxic rat lung when compared with the rats exposed to ambient air, but there was no difference between these groups in the prolonged depression of vascular responsiveness to hypoxia or angiotensin II. Thus, in both models of lung endothelial cell injury, the pulmonary vascular responses to ACh were intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetylcholine; Acute Disease; Animals; Chronic Disease; In Vitro Techniques; Lung Diseases; Male; Microbial Collagenase; Microscopy, Electron; Oxygen; Perfusion; Pulmonary Circulation; Pulmonary Edema; Rats; Rats, Inbred Strains; Thiourea; Vascular Diseases; Vasodilation

Using the thiocarbamide model of acute lung injury in rats, we found that alpha-naphthylthiourea (ANTU) caused lung endothelial cell injury, as evidenced by increased permeability edema and decreased angiotensin I conversion. These effects were associated with enhanced pulmonary vascular reactivity. Recurrent ANTU lung injury caused pulmonary hypertension. The water-soluble thiocarbamide thiourea caused cultured vascular endothelial cells to release neutrophil chemoattractant activity. We speculate that endothelial cell injury may modulate the function of vascular smooth muscle and blood leukocytes.

Topics: Angiotensin II; Animals; Endothelium; Hypertension, Pulmonary; Lung; Lung Diseases; Male; Muscle, Smooth, Vascular; Neutrophils; Pulmonary Edema; Rats; Rats, Inbred Strains; Thiourea

Topics: Endothelium; Free Radicals; Humans; Lung Diseases; Microcirculation; Models, Biological; Oxygen; Superoxides; Thiourea

Topics: Animals; Dogs; Edema; Lung Diseases; Oxygen; Pulmonary Edema; Respiration; Thiourea

Topics: Animals; Exudates and Transudates; Lung Diseases; Pleura; Pleural Effusion; Pulmonary Edema; Rats; Thiourea