Mary J. Schiedt

Effects of intratracheal administration of bleomycin on GSH-shuttle enzymes, catalase, lipid peroxidation, and collagen content in the lungs of hamsters.

Intratracheal administration of one unit of bleomycin increased significantly the glucose-6-phosphate dehydrogenase activity to 147, 135, 163, 207, 278, and 148% of the control at 1, 2, 4, 7, 14, and 21 days post-treatment, respectively. The glutathione peroxidase activity was significantly increased to 147 and 124% of the control at 7 and 14 days post-treatment, respectively. The glutathione reductase and catalase activities were significantly elevated to 132, 174, and 145% of the control in the former and 160, 213, and 160% of the control in the latter case at 7, 14, and 21 days post-treatment, respectively. The amount of thiobarbituric acid reacting products as an index of lipid peroxidation was found to be significantly increased to 251, 248, and 253% of the control at 4, 7, and 14 days after treatment, respectively. The amount of total lung collagen in treated hamsters was significantly increased to 140, 197, and 245% of the control at 7, 14, and 21 days post-treatment, respectively. These findings indicate that the increases in the activities of antioxidant enzymes in lungs of bleomycin-treated hamsters result from the multiple cyto-dynamic events such as infiltration of inflammatory cells, and reparative and proliferative processes which generally follow lung injury caused by any oxidant.

Biochemical and structural alterations of hamster lungs in response to intratracheal administration of bleomycin

Abstract One unit of bleomycin was administered intratracheally to hamsters and an equivalent volume of saline to controls. Morphological changes within lungs of bleomycin-treated hamsters consisted of a diffuse hemorrhagic interstitial pneumonia at 7 days post-treatment. Lungs contained less hemorrhage and edema but increased numbers of mononuclear inflammatory cells and thickened interalveolar walls at 14 days post-treatment. A diffuse mononuclear cell infiltrate with multifocal areas of fibrosis later predominated. The protein, RNA, and DNA levels in bleomycin-treated hamsters were consistently and significantly elevated at 4 (except DNA), 7, 14, 21, and 28 days after treatment. The Ca 2+ levels in lungs of these animals at the corresponding times were increased by 158, 194, 36, 22, and 8% without any change in plasma Ca 2+ . Lung soluble collagen was increased by 124, 207, 121, and 30% at 7, 14, 21, and 28 days, respectively, after bleomycin treatment. The increases in insoluble collagen were 65, 108, 132, and 91% at the corresponding times. The lung cAMP levels at 4, 7, 14, 21, and 28 days were 176, 164, 132, 158, and 96% of control, respectively, and cGMP at the corresponding times were 50, 81, 222, 198, and 137% of control. These data suggest that shifts in the intracellular levels of cAMP, cGMP, and Ca 2+ are associated with early lung changes induced by bleomycin insult and may serve as indicators to gauge the severity and progression of lung damage.

The effects of ozone and paraquat on PGF2α and PGE2 levels in plasma and combined pleural effusion and lung lavage of rats

Abstract The effects of lung toxins O 3 and paraquat on PGF 2α and PGE 2 levels of plasma and combined pleural effusion and lung lavage were studied in male Sprague-Dawley rats using radioimmunoassay. The plasma concentration of PGF 2α in rats exposed to 4 ppm O 3 for 2, 4, and 8 hr was increased by 186, 109, and 25%, respectively. The increases in PGF 2α level in pleural effusion-lung lavage of these rats at the corresponding times were 82, 0, and 65%. The plasma concentrations of PGF 2α and PGE 2 were increased in response to treatment with paraquat (45 mg/kg i.p.). The increases in plasma PGF 2α at 1.5, 3, 6, 12, 24, and 48 hr following paraquat treatment were 223, 128, 47, 270, 195, and 130%, respectively. The increases in plasma concentration of PGE 2 at the corresponding times were 9, 88, 279, 323, 325, and 66%. In view of a dramatic increase in the prostaglandin level of plasma and pleural effusion-lung lavage following exposure to O 3 and treatment with paraquat, it has been suggested that an increased level of prostaglandin in plasma and lung lavage (done in case of O 3 ) might offer some diagnostic value for the morphological and functional impairment of the lung.

The Effects of Paraquat and Superoxide Dismutase on Pulmonary Vascular Permeability and Edema in Mice

Intraperitoneal administration of 50 mg/kg paraquat dichloride to mice significantly increased pulmonary vascular permeability at 24 and 48 hr, as measured by 125I-albumin content of alveolar lavage. Lung edema, measured by lung weight as percent body weight, was significantly increased 48 hr after paraquat treatment. Intravenous administration of four doses of superoxidase dismutase at 12-hr intervals (i.e., one before and three after paraquat treatment) failed to inhibit paraquat-induced increased pulmonary vascular permeability and pulmonary edema. Superoxide dismutase treatment also failed to reduce mortality and had no significant effect on the death time course in animals challenged with paraquat. The results of this study suggest that acute toxic effects of paraquat, such as increased pulmonary vascular permeability and pulmonary edema, may not be mediated through the generation of superoxide anion.

Etiology of sarcoplasmic reticulum calcium release channel lesions in doxorubicin-induced cardiomyopathy

Alterations in the native function of the ryanodine-sensitive Ca2+ release channel complex of sarcoplasmic reticulum (SR) isolated from rat cardiac ventricles during acute and chronic exposure to doxorubicin are examined. Compared to control SR, actively loaded SR from animals exposed to a single intravenous dose of doxorubicin exhibit faster rates of doxorubicin-induced Ca2+ release and the occupancy of [3H]ryanodine is significantly enhanced with subsequent exposure of SR membranes to doxorubicin in vitro. One week after acute exposure to doxorubicin in vitro, the EC50 for activation of the binding of [3H]ryanodine by Ca2+ is not significantly different from control SR. However, the persistence of doxorubicin-sensitized SR channels appears to be latent since repeated exposure to doxorubicin in vitro significantly enhances receptor occupancy in SR obtained from the treated rats compared to control SR. Ryanodine receptors from rats chronically exposed to doxorubicin consistently exhibit a higher sensitivity to activation Ca2+ which persists at least 4 weeks following the last injection of drug. Chronic exposure produces a concomitant reduction in the capacity of [3H]ryanodine binding sites. The marked decrease in receptor density observed with SR from doxorubicin-treated rats coincides with significant reduction in body weight, suggesting a possible influence of nutrition. However, sodium dodecyl sulfate polyacrylamide electrophoresis indicates no significant loss of the high molecular weight subunit of the ryanodine receptor, suggesting that loss of [3H]ryanodine-binding capacity may be the result of progressive and permanent channel desensitization. Consistent with desensitized receptors, membrane vesicles prepared from rats chronically exposed to doxorubicin take up significantly more Ca2+ and exhibit significantly reduced rates of doxorubicin or Ca2+/ryanodine induced Ca2+ release. The data demonstrates (i) doxorubicin inflicts cumulative SR channel lesions in vivo, (ii) a persistent sensitization of the SR channel to activation by Ca2+ and (iii) a significant and apparently irreversible reduction in the number of functional channel complexes.

Effects of paraquat on plasma glucose, cortisol, catecholamines, and insulin in the beagle.

Paraquat is known to produce hyperglycemia in rodents, although the mechanisms responsible for the hyperglycemic effect of paraquat are not clearly understood. In this study we report the effects of paraquat (25 mg/kg iv) on plasma glucose, cortisol, catecholamines, and insulin in dogs. Paraquat caused a significant increase in plasma glucose level at all times of measurement except at 0.5 hr following paraquat administration. The cortisol levels after paraquat treatment were increased to 133, 305, 279, 418, 517, 672, and 567% above zero time control at 0.5, 1.5, 3, 6, 12, and 24 hr, and at death time respectively. The catecholamines at these times were increased to 42, 17, 72, 118, 138, 226, and 435% above the control. In contrast to cortisol and catecholamines, the plasma insulin levels after paraquat treatment were significantly decreased at 3, 6, 12, and 24 hr. These hormonal observations can explain, at least in part, the observed hyperglycemia, since all promote hyperglycemic states. For example, cortisol is gluconeogenic, catecholamines are glycogenolytic, and lower insulin levels result in depressed peripheral glucose utilization.

Effects in vitro and in vivo of thioureas on acetylcholine esterase activity of rat tissues.

Abstract In view of data available that accumulation of acetylcholine in the lung leads to pulmonary edema formation, the effects of thiourea (TU), phenylthiourea (PTU) and α-naphthylthiourea (ANTU) on lung acetylcholine esterase (AchE) activity were examined in vitro and in vivo. ANTU and PTU produced a concentration-dependent inhibition of lung AchE activity in vitro. The Sped50 values of ANTU and PTU were 2.8 × 10−4 and 5 × 10−4 M respectively. No significant inhibition in AchE activity of the lung occurred in response to any concentration of TU. The mechanisms of AchE inhibition due to ANTU appeared to be competitive. The apparent Km for lung AchE averaged 7.23 × 10−4 M and the Ki for ANTU averaged 1.11 × 10−4 M. ANTU at 5 × 10−4 M inhibited the AchE activity of all examined tissues in vitro. An edema-producing dose of ANTU had no effect on AchE activity of any tissue except the brain. A failure to demonstrate the inhibitory effect in vivo of ANTU on AchE activity has been discussed in this paper. Pretreatment with atropine offered no protection against the pulmonary edema-producing ability of ANTU. The data collected in the present report indicate that inhibition of lung AchE is probably not the mechanism of ANTU-induced pulmonary edema. The significance of brain AchE inhibition in response to an edema-producing dose of ANTU is not known.

Effects of pretreatment with anti-inflammatory drugs on ozone-induced lung damage in rats.

Summary The effects of pretreatment with acetylsalicylic acid (aspirin), hydrocortisone, indomethacin, and heparin administered ip against the pulmonary edema produced by O3-exposure (4 ppm for 4 hr) were studied in rats. These anti-inflammatory drugs were found to alter the injurious effect of O3 on lung differently. First, aspirin at the high dose (125 mg/kg) accentuated O3-induced lung injury, and had no effect at the low dose (10 mg/kg); second, hydrocortisone (50 mg/kg) failed to have any effect; third, indomethacin at a high dose (20 mg/kg) offered a significant degree of protection, but had no effect at the low dose (2.5 mg/kg); and fourth, heparin (1000 units/kg) also offered a significant degree of protection against the lung damage normally induced by O3-exposure. Several mechanisms for the favorable and unfavorable interactions of anti-inflammatory drugs with O3-exposure are discussed. This research was supported by the Davis Faculty Research Grant and the Chancellors Patent Fund, University of California, Davis. We are also grateful to Dr. Walter Tyler, Director of the California Primate Research Center at Davis for allowing us the use of the ozone-exposure chamber facility.

Pharmacokinetics of [14C]-Paraquat and Associated Biochemical and Pathologic Changes in Beagle Dogs Following Intravenous Administration

Abstract A single toxic dose (25 mg/kg, iv) of [14C]-paraquat (PQ) caused vomiting in all six Beagle dogs but mild diarrhea in only two dogs. All dogs manifested salivation and labored breathing within 6 to 9 hours and died between 32 and 36 hours postdose. The activities of plasma lactic dehydrogenase and creatine phosphokinase were generally increased at all times after PQ treatment. The glutamic oxaloacetic transaminase activity was increased at 6, 12, 24 hr and at death. The plasma angiotensin converting enzyme activity was unaffected. The plasma creatinine levels were generally increased and renin levels were increased at 12, 24 hr and at death. The hematocrit and plasma protein were increased at 6, 12 and 24 hr. A significant decrease in plasma K+, Na+, and Cl− was obtained at 6 hr after treatment and continued until death. The plasma concentration time curve showed a biphasic decline with a half life of 42.5 min for the alpha-phase. The distribution volume was 25.8% of body weight. The dogs dying from PQ toxicity showed the highest amount of PQ in bile followed by kidney, lung, liver, spleen, heart, adrenal glands, pancreas, thymus and muscle. Tissue paraquat concentrations in the first three organs correlated well with the severity of pathologic changes induced by this herbicide. The kidney had tubular necrosis characterized by segmental degeneration and coagulation necrosis of epithelium of the proximal convoluted tubules. The lungs showed patchy edema and alveolar hemorrhage. Hepatic changes included hepatocellular vacuolation. It was concluded from this study that secretion of PQ in bile may contribute to the total body clearance of this compound and that renal failure is a major cause of death in dogs acutely poisoned with paraquat.

Effects of three cysteine pro-drugs on bleomycin-induced lung fibrosis in hamsters

&NA; The cysteine pro‐drug Z2196 ((2RS, 4R)‐2‐methylthiazolidine carboxylic acid) and two drugs with methyl esters attached to Z2196 (Z2197 and Z2199) were evaluated for antifibrotic effects in the hamster bleomycin model of lung fibrosis. Each drug or phosphate‐buffered saline (PBS) was given daily (300 mg/kg intraperitoneally) for 2 days before intratracheal instillation of bleomycin (7.5 units/kg) or saline for an additional 13 days. Lung collagen measured as hydroxyproline was significantly increased to 138% of the control groups in the PBS + Bleomycin treated group, but the Z2196 + Bleomycin group was increased to 108% and was not statistically different from controls. Protein content of brochoalveolar lavage supernatant in PBS + Bleomycin treated hamsters was significantly increased to 326% of controls. The protein content of bronchoalveolar lavage supernatant for all cysteine pro‐drug + Bleomycin treated hamsters was increased to 160% of PBS + Bleomycin treated hamsters. All the Bleomycin treated hamsters had significantly more cells and more neutrophils recovered in bronchoalveolar lavage than controls. The PBS + Bleomycin treated hamsters had significantly more lymphocytes in bronchoalveolar lavage than all the other treatment groups. The Z2196 +Bleomycin and Z2197 +Bleomycin hamsters had significantly less monocytes in BALF than PBS + Bleomycin hamsters. The lung total sulfhydryl and nonprotein sulfhydryl in PBS + Bleomycin treated hamsters were increased to 210% and 253% of controls, respectively, whereas in Z2196 +Bleomycin hamsters they were increased to 152% and 153%, respectively. Histopathology of PBS + Bleomycin hamsters showed a diffuse mixed mononuclear alveolitis, multifocal fibrosis and peribronchiolar fibrosis, whereas Z2196 + Bleomycin hamsters showed notably less alveolitis and fibrosis. These observations were supported by a 60% decrease in the volume of lesion in Z2196 + Bleomycin hamsters compared with PBS + Bleomycin hamsters. None of the cysteine pro‐drugs given daily for 15 days and a single dose of saline intratracheally resulted in any mortality or any detectable lung injury or fibrosis. It was concluded that treatment with the cysteine pro‐drug Z2196 inhibits most of the rise in non‐protein sulfhydryl and collagen and some of the inflammation resulting from bleomycin treatment in hamsters, whereas Z2197 and Z2199 failed to manifest any influence on inflammation and collagen accumulation.