Renal and hepatic microsomal enzyme stimulation and renal function following three months of dietary exposure to polybrominated biphenyls.

Polybrominated biphenyls (PBB) stimulate microsomal enzyme activity and produce a variety of toxic manifestations, including renal and hepatic histopathological changes. Therefore, it was of interest to determine the effect of chronic exposure to PBB on renal and hepatic microsomal enzyme stimulation and renal function. Adult Sprague-Dawley rats were fed diets containing 0 or 100 ppm of PBB for 3 months. Treatment with PBB retarded weight gain and increased the liver to body weight ratio but did not alter kidney to body weight ratio. Biphenyl-4-hydroxylase (BP-4-OH) and biphenyl-2-hydroxylase (BP-2-OH) activities were elevated in the kidney and liver following treatment with PBB. Exposure to PBB increased aryl hydrocarbon hydroxylase (AHH) activity in the kidney and liver. Epoxide hydratase (EH) activity was increased in the liver but decreased in the kidney following exposure to PBB. A three-month exposure to PBB had no effect on blood urea nitrogen, the clearance of inulin, p-aminohippurate (PAH), or fractional sodium excretion. Similarly, the in vitro accumulation of PAH and N-methylnicotinamide (NMN) in thin renal cortical slices and ammoniagenesis and gluconeogenesis in renal cortical slices were not affected by PBB. In conclusion, chronic exposure to PBB resulted in significant alterations in renal and hepatic microsomal enzyme activities but had no detectable effect on renal function. These experiments suggest that alterations in microsomal enzyme activities following PBB do not lead to impairment of renal function; however, this compound may sensitize the kidney to toxicity produced by agents administered subsequent to PBB.     

Effects on cytokines and histology by treatment with the ACE inhibitor captopril and the antioxidant retinoic acid in the monocrotaline model of experimentally induced lung fibrosis

Monocrotaline (MCT), a pyrrolizidine alkaloid extracted from the shrub Crotalaria spectabilis, induces in the lungs of many mammalian species severe hypertension and fibrosis. Previous work with MCT-induced lung disease in rats has shown that some of the steps to progressive fibrosis can be interrupted or decreased by intervention with retinoic acid (RA) or with the angiotensin converting enzyme inhibitor, captopril. This report emphasizes the pathology and cytokines present in lungs of rats in the MCT model of hypertension and fibrosis in 8 treatment groups, six per group: (1) controls, not treated; (2) captopril; (3) RA; (4) combined captopril and RA. Groups 5-8 replicated groups 1-4 and also received MCT subcutaneously. Tissues were harvested at 28 days for histopathology and measurement of cytokines TGFbeta, TNFalpha, interleukin 6, and IFN_. TGFbeta was depressed at 28 days by MCT, an effect reversed by a combination of captopril and RA. RA influences production of an important Th1 cytokine, IFN_, and demonstrated the greatest limitation of MCT-induced TNFalpha. The MCT-induced lung pathology of vasculitis, interstitial pneumonia and fibrosis was limited by captopril. Smooth muscle actin was overexpressed in MCT treated animals receiving RA, an effect reduced with captopril. Overall, the study confirmed the existence of a protective effect for both captopril and RA from MCT-induced lung damage at 30 days. No synergistic or antagonistic activity was observed when the two drugs were administered together. Each of the drugs exerts different and particular effects on serum and tissue levels of various cytokines, suggesting that each drug is efficient at different points of attack in the control of lung fibrosis.     

Red blood cells augment transport of reactive metabolites of monocrotaline from liver to lung in isolated and tandem liver and lung preparations

Monocrotaline (MCT) is a pyrrolizidine alkaloid that causes pulmonary hypertension in rats by mechanisms which remain largely unknown. MCT is thought to be activated in the liver to a reactive intermediate that is transported to the lung where it causes endothelial injury. Our previous pharmacokinetic work demonstrated significant sequestration of radioactivity in red blood cells (RBCs) of rats treated with [14C]MCT. To determine whether this RBC sequestration might be important in the transport of reactive MCT metabolites, we compared the effect of inclusion of RBCs in the perfusion buffer on the extent of covalent binding of [14C]MCT to rat lungs in tandem liver-lung preparations. The potential effect of RBCs in stabilizing reactive intermediates was evaluated by preperfusion of isolated liver preparations with [14C]MCT with and without RBCs, separation and washing of the RBC fraction, and subsequent (90 min later) perfusion of washed RBCs or buffer alone in isolated perfused lungs. Covalent binding to lung tissues was determined by exhaustive methanol/chloroform extractions of unbound label from homogenized lung tissue followed by scintillation counting of residual 14C. Covalent binding was expressed as picomole MCT molecular weight equivalents/mg protein. Comparison of the relative capability of these isolated organ preparations for conversion of MCT to polar metabolites was done by extraction and HPLC analysis of perfusate at the end of the experiment. Isolated livers converted 65-85% of MCT to polar metabolites compared with less than 5% conversion in the isolated lungs. Inclusion of RBCs in the buffer of tandem lung liver preparations perfused with 400 microM [14C]MCT increased the covalent binding to the lung from 97 +/- 25 (buffer alone) to 182 +/- 36 (buffer + RBC) pmol/mg protein. At the end of these perfusions, RBCs contained 1552 +/- 429 pmol/mg hemoglobin of which 333 +/- 98 pmol/mg hemoglobin resisted exhaustive solvent extraction. After 90 min at room temperature, buffer with 400 microM [14C]MCT preperfused in isolated livers resulted in covalent binding to isolated perfused lung of 0.8 +/- 0.4 pmol/mg protein while washed RBCs isolated from buffer of similar liver preperfusions preparations resulted in 53 +/- 7 pmol/mg protein bound to lung. Control groups perfused with 400 microM [14C]MCT in buffer or buffer + RBCs through isolated lungs only resulted in covalent binding of 2 +/- 1 or 1 +/- 0.6 pmol/mg protein respectively. We conclude: (1) RBCs significantly augment the transport of lung reactive MCT metabolites from the liver to the lung.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparative alterations in extrahepatic drug metabolism by factors known to affect hepatic activity.

Various factors known to alter hepatic drug metabolism were examined for their effects on drug metabolism in certain extrahepatic organs, viz. lung and kidney. The prominent sex-related differences in drug metabolism in rat liver were not seen in either lung or kidney. Pretreatment of rats with phenobarbital produced the expected large increases in hepatic NADPH cytochrome c reductase, cytochrome P-450. aminopyrine demethylase and biphenyl hydroxylase activities without concomitant changes in any of these parameters in lung, and only scattered and smaller changes in kidney. 3-Methylcholanthrene (3-MC) pretreatment significantly increased cytochrome P-450 levels in all three organs. Pretreatment of rats with carbon tetrachloride (CCl₄) produced consistent inhibition of mixedfunction oxidation in hepatic microsomes. but the extrahepatic effects were less predictable and were both organ- and enzyme-specific. An increase in renal UDP-glucuronyltransferase activity was observed after CCl₄ treatment that paralleled a similar but larger increase observed in liver. Extrahepatic NADPH cytochrome c reductase and N-methyl-p-chloroaniline demethylase values were unaffected by CCl₄. Lung and kidney responded in a like manner to liver to the additions in vitro of β-diethylaminoethyl diphenylpropylacetate (SKF-525A). Losses in enzyme activities in lung and kidney microsomes roughly paralleled those of liver when stored as pellets for up to 14 days at ?70°. Two or 4 days of starvation produced substrate-specific changes in enzyme-specific activity in liver and kidney, with lung appearing resistant to the effect. When enzyme activity was expressed on a whole organ basis, however, lung cytochrome P-450 values decreased significantly and parameters from liver and kidney increased or decreased in a substrate-specific manner. It is concluded that some physiological and pharmacological factors that influence hepatic drug metabolism produce similar effects in lung and kidney, while other factors produce organ-specific effects.     

Effect of paraquat treatment of rats on disposition of 5-hydroxytryptamine and angiotensin I by perfused lung.

Rats were injected with the herbicide, paraquat dichloride (25 mg/kg, i.p.), and their lungs were perfused 2–28 days later. Isolated lungs from rats treated with paraquat (PQ) 3 or 4 days before perfusion removed significantly less perfused 5-hydroxytryptamine (5-HT) than did saline-injected controls. This effect was not caused by PQ directly, since perfusion of lungs from untreated animals with PQ did not alter removal of co-perfused 5-HT. Monoamine oxidase activity of600 g supernatan fractions of homogenates of lungs from PQ-treated rats was also reduced compared to controls. Although removal of perfused angiotensin I (1 ng/ml) by isolated lungs was not altered by PQpretreatment, antgiotensin-converting enzyme activity in 600 g supernatant fractions of lung homogenates was reducedd significantly. These results suggest that PQ damages pulmonary endothelium and impairs the metabolic function of lung.     

Induction of drug-metabolizing enzymes and toxicity of trans-stilbene oxide in rat liver and kidney

The effect of trans-stilbene oxide (TSO) on organ function and morphology and on drug-metabolizing enzymes was determined in male Sprague-Dawley rats. TSO (300 or 600 mg/kg) was administered i.p., once daily for 5 consecutive days. At a dose of 3400 mg/kg, TSO did no alter body weight, but increased liver weight. The higher dose (600 mg/kg) markedly decreased body weight. TSO treatment (300 mg/kg) induced several drug-metabolizing enzymes. Epoxide hydrolase activity was enhanced in the liver, kidney and lung. In contrast, arylhydrocarbon hydroxylase activity was not significantly altered. Glutathione S-transferase activity, with 1-chloro-2,4-dinitrobenzene as substrate, and uridine diphosphoglucuronyl transferase activity, with p-nitrophenol as substrate, were also increased in the liver and kidney after TSO treatment. It appears that TSO induces hepatic and renal enzyme activities in a similar manner. Treatment with the higher dose of TSO depressed accumulation of p-amino-hippurate by renal cortical slices and increased blood urea nitrogen concentration. Histological examination of kidney sections after treatment with TSO revealed no abnormality. The lower dose led to negligible alteration in liver and the higher dose resulted in mild to moderate hepatic cellular.     

Subacute effects of methyl parathion on antioxidant defense systems and lipid peroxidation in rats

In this study we aimed to examine how methyl parathion (MP) at sublethal dosages affects on malondialdehyde (MDA) content and antioxidant defense system (ADS) such as reduced glutathione (GSH), glutathione reductase (GR), superoxide dismutase (SOD) and glutathione-S-transferase (GST) in various tissues of rats exposed to 19 and 38 millimole (mM) MP dosages as drinking water ad libitum for 28 days continuously. MDA significantly increased in all the tissues except for in the lungs of rats treated with both dosages of MP. With regard to the ADS, SOD significantly decreased in the lungs tissue whereas increased in the erythrocytes with two dosages of MP. GR activity significantly decreased in the erythrocytes treated with both dosages of MP, but decreased in the lungs and liver tissues with 38 mM MP treatment. GST activity significantly elevated in all the tissues except for in the liver treated with 38 mM dosage but did not change with 19 mM. Meanwhile, GSH depletion in all the tissues except lungs of rats treated with both dosages of MP was found to be significant. The observations presented led us to conclude that after the administrations of MP promote MDA content and fluctuate in the ADS in rats.     

Platelets and the puzzles of pulmonary pyrrolizidine poisoning

Pyrrolizidine alkaloids such as monocrotaline (MCT) are toxic plant constituents which poison livestock and humans. Low doses of MCT given to rats result in cardiopulmonary pathophysiologic sequelae similar to forms of chronic pulmonary hypertension in man. This provides a useful model of human disease. The toxicology of MCT is complex, and the mechanisms by which it causes lung injury, pulmonary hypertension, and right heart enlargement have remained elusive despite intensive study by numerous investigators. MCT is bioactivated by the liver to a reactive, electrophilic pyrrole (MCTP) that travels via the circulation to the lung, where injury results. When low, intravenous doses of MCTP are given to rats, a delay of several days occurs before lung injury and pulmonary hypertension become apparent. Moderate depletion of blood platelets around the time of the onset of lung injury lessens the subsequent development of right ventricular enlargement, suggesting a reduction in the pulmonary hypertensive response to MCTP. This observation prompted a study of the role of platelet-derived mediators in the cardiopulmonary response to MCTP. A stable analog of thromboxane A2(TxA2) caused a greater increase in right ventricular pressure in MCTP-treated rats compared to controls, and lungs isolated from MCTP-treated rats produced more TxB2 than those of controls. However, administration of drugs that either inhibited thromboxane synthesis or antagonized the effects of thromboxane did not afford protection from MCTP in vivo. Serotonin (5HT), another vasoactive mediator released by platelets, caused an exaggerated vasoconstrictor response in isolated lungs from rats treated with MCTP. Moreover, removal and inactivation of circulating 5HT by the pulmonary vasculature was impaired by treatment of rats with MCTP. However, administration of 5HT receptor antagonists did not attenuate the cardiopulmonary effects of MCTP in vivo. These results suggest that neither TxA2 nor 5HT is the sole mediator of the pneumotoxicity due to MCTP. Thus, the mechanism by which platelets are involved in the pathogenesis of the pneumotoxic response to MCTP remains an unsolved puzzle.     

Effects of inorganic nitrate in a rat model of monocrotaline‐induced pulmonary arterial hypertension

The nitrate‐nitrite‐nitric oxide (NO) pathway represents an alternative source of NO generation, which is independent of NO synthase and potentiated by hypoxia. Augmentation of this pathway by dietary nitrate has proven favourable effects in several cardiovascular disease models. However, less is known regarding its potential value in pulmonary arterial hypertension (PAH). The aim of this study was to assess the effects of oral inorganic nitrate administration in monocrotaline (MCT)‐induced PAH. Male 12‐week‐old Wistar rats were injected subcutaneously with monocrotaline (MCT, 60 mg/kg). Nitrate treatment (0.3 or 1 mmol/kg/d; drinking water) commenced on day 12 following the MCT injection and continued for 16 days. Nitrate administration did not attenuate right ventricular (RV) hypertrophy, increased lung weight and up‐regulated mRNA expression of brain natriuretic peptide. Plasma nitrate and nitrite levels were significantly increased as well as lung nitrate level, whereas nitrite lung level was decreased following nitrate treatment (1 mmol/kg/d). MCT‐induced PAH resulted in an increased MnSOD protein level, which was not observed following nitrate treatment. MCT‐associated up‐regulation of nNOS in the lung appeared to be dose‐dependently prevented by nitrate treatment. Western blot analysis did not reveal any differences in eNOS, iNOS, XO or gp91phox expression in the lungs among the groups. In conclusion, nitrate treatment did not significantly attenuate pathological RV and lung remodelling in the rat MCT model of PAH. The suppression of MnSOD and nNOS expression by nitrate could be interpreted as reduced demand of endogenous antioxidant defence in this model.     

Comparative gastric ulcerogenic effects of meseclazone, 5-chlorosalicylic acid and other nonsteroidal anti-inflammatory drugs following acute and repeated oral administration to rats

Rats injected with α-methylglutamate (MGA) excreted less ammonium, and renal slices from these rats produced less ammonia. When renal slices from normal rats were incubated in MGA, ammoniagenesis from glutamine decreased slightly; but glutamate accumulation increased markedly. In contrast, dl-methionine dl-sulfoximine (MS), a relatively specific inhibitor of glutamine synthesis and transferase, enhanced both glutamate accumulation and ammoniagenesis by slices from control rat kidneys. While it is generally accepted that MGA inhibits glutamine synthetase and transferase activity, the results with MGA do not mimic those found with MS. Additionally, MGA decreased ammoniagenesis and increased glutamate accumulation in slices already incubating in MS and in slices from acidotic rats. These are circumstances where slices should have minimal synthetase and transferase activity. It is concluded that MGA decreases renal ammoniagenesis through other pathways, perhaps via inhibition of the glutaminase and the glutamate dehydrogenase routes.     

Furosemide accumulation by renal tissue.

Furosemide accumulation by rabbit kidney cortical slices increased with incubation time, reaching a plateau by 60–90 min. Furosemide uptake by kidney slices from rabbits, dogs, mice and rats was inhibited by dinitrophenol, ouabain and probenecid, and was decreased by incubation at 0°, anoxia or the use of sodium-free medium. Furosemide slice/medium ratios decreased with increasing concentration of furosemide in the incubation medium. Addition of furosemide to medium containing rat kidney slices and either p-aminohippurate (PAH) or N-methylnicotinamide (NMN) produced a dose-related inhibition of PAH, but not NMN, accumulation. It is concluded that furosemide is actively transported by the renal organic anion transport system.     

Acid and alkaline phosphatase activities in a novel phosphorothionate (RPR-11) treated male and female rats. Evidence of dose and time-dependent response

The effect of a novel phosphorothionate, the methyl ester of 2-butenoic acid-3-diethoxy phosphinothioyl (RPR-II) was studied on membrane bound target enzymes Acid (AcP) and Alkaline (AkP) Phosphatases in different tissues of male and female albino Wistar rats. Three sub-chronic doses 0.014 (low), 0.028 (medium) and 0.042 (high)mg/kg-1 were administered to the rats daily for a period of 90 days. The long term and repeated administration of RPR-II caused significant increase of AcP and AkP in serum and kidney (AcP), whereas these enzymes simultaneously decreased significantly in liver, kidney (female rat AkP) and lung tissues in both male and female rats after 45 and 90 days of treatment. However, the kidney AcP increased significantly in both the sexes which is suggestive of an increase in synthesis of this enzyme which may be an adaptive mechanism to the toxicant stress. The changes in serum, liver, kidney and lung of both male and female rats by this compound were statistically significant when compared with two way Anova showing that they are dose and time dependent. The alterations in male rats were statistically insignificant when compared with female rats showing no sexual dimorphism by this compound. Recovery was observed after 28 days of post treatment (withdrawal study) indicating reversal of the toxic symptoms once the toxicant is removed. High degree negative correlation was observed for serum versus liver and lung and in other cases substantial correlation was observed. The changes observed in these enzymes showed that liver was most susceptible followed by lung and kidney. There are marker enzymes and their increase in different tissues might be due to the increased permeability of plasma membrane or cellular necrosis, showing the stress condition of the treated rats. This investigation elucidates the effect of these biomarker enzymes which increased in blood, might be due to the necrosis of liver, kidney and lung tissues by this compound.     

Selective inhibition of rat pulmonary monooxygenase by O, O, S-trimethyl phosphorothioate treatment

The effects of oral administration of O,O,S-trimethyl phosphorothioate (OOS), an impurity present in widely used organophosphorus insecticides, were studied using pulmonary and hepatic microsomal enzymes of rats. The animals were treated with OOS at 10, 20 and 40 mg/kg, and were killed on day 3 after treatment. Their relative lung weights increased markedly at 20 and 40 mg/kg, increasing 94% at the highest dose, whereas the weight of liver decreased. At 20 mg/kg OOS, the cytochrome P-450 content of the lung and liver decreased to 83 and 80% of the control levels respectively. Pulmonary microsomal 7-ethoxycoumarin (7-Ec) O-deethylase decreased in a dose-dependent manner; activities were less than 10% of control at the 40 mg/kg dose. The activity of pulmonary coumarin hydroxylase also decreased following OOS treatment, but the decrease was not dose-dependent since no activity was detectable at doses over 10 mg/kg. In contrast, the effect of OOS treatment on hepatic monooxygenase activity was moderate. 7-Ec deethylase activity was not affected by OOS treatment at any dose level, while p-nitroanisole (p-NA) demethylase activity was decreased only at the 40 mg/kg dose of OOS. Pulmonary malathion carboxylesterase activity was not affected by OOS treatment. In contrast, a dose-dependent decrease was observed in the liver carboxylesterase. Time course effects of OOS treatment on these parameters were examined by treating rats at 20 mg/kg. The animals were killed 0.5, 1, 3 and 7 days after the treatment. The 7-Ec deethylase activity of pulmonary microsomes was decreased on days 0.5, 1 and 3 after treatment, the maximum decrease being observed on day 1. Significant decreases were not observed in hepatic microsomal activities of 7-Ec deethylase or p-nitroanisole demethylase throughout the experimental period; rather, these activities were higher on day 7. Hepatic microsomal malathion carboxylesterase was lower on days 0.5, 1 and 3 after OOS treatment.     

Development of morphologic, hemodynamic, and biochemical changes in lungs of rats given monocrotaline pyrrole

A single, intravenous administration of a low dose of monocrotaline pyrrole (MCTP), a derivative of the pyrrolizidine alkaloid monocrotaline (MCT), induces progressive pulmonary hypertension and right ventricular hypertrophy (RVH) in rats. The temporal relationship between morphologic alterations, biochemical markers of lung injury, and the development of pulmonary hypertension was determined during the developing pulmonary disease. Three days after a single iv injection of 3.5 mg/kg MCTP, small increases in bronchoalveolar lavage (BAL) fluid lactate dehydrogenase (LDH) activity and accumulation in the lungs of intravenously administered 125I-bovine serum albumin (BSA) were associated with minimal to mild interstitial edema around large airways and blood vessels. By Day 5, BAL fluid LDH activity and 125I-BSA accumulation had increased further, and lung weight/body weight ratio and BAL fluid protein concentration were greater than those of control. Interstitial edema was more pronounced and involved patches of alveolar septal walls. A mild increase in numbers of mononuclear cells, including hypertrophied interstitial cells, was evident in these areas. Walls of pulmonary arteries less than 60 microns in diameter were mildly thickened. By Day 8, scattered clusters of alveolar sacs contained serous exudate, and interstitial mononuclear infiltrates were more pronounced. Mild to moderate thickening of arterial walls was apparent in small and large vessels. By Day 14, pulmonary arterial pressure was elevated and RVH was evident. Arterial walls were thickened and had hypertrophy of medial smooth muscle cells and intercellular edema, which was particularly prominent in areas with perivascular interstitial inflammation. Large patches of lung interstitium and alveolar lumens contained serous or fibrinous exudate. In summary, a single, intravenous administration of MCTP induced a delayed and progressive pulmonary microvascular leak, interstitial inflammation, and alterations in muscular blood vessels which resulted in pulmonary hypertension within 14 days. These morphologic, biochemical, and hemodynamic changes are nearly identical to alterations induced by the parent alkaloid, MCT.     

Effects of Vepacide (Azadirachta indica) on aspartate and alanine aminotransferase profiles in a subchronic study with rats

The aim of this study was to ascertain the long-term effects of Vepacide, a neem-based pesticide on biochemical profiles. Albino Wistar rats were treated orally with 80 (low), 160 (medium) and 320 mg/kg (high) doses of Vepacide in coconut oil for 90 days. Control rats received the same volume of the vehicle. Vepacide caused increase of aspartate and alanine aminotransferase in serum, kidney and lung, and these enzymes decreased in liver in both male and female rats when measured after 45 and 90 days of treatment. The two-way analysis of variance (ANOVA) showed that the alterations in these enzymes were dose- and time-dependent. Sexual dimorphism was observed when male rats were compared with female rats (Student t-test at P< 0.05). Positive correlation was observed with regard to these enzymes between serum, kidney and lung, whereas in the case of serum and liver, a negative correlation was recorded. These enzyme profiles elucidate that they increased in serum with simultaneous decrease in liver, indicating necrosis of liver, whereas in other tissues, the level of enzymes increased, showing an adaptive mechanism due to the chemical stress. The affected enzymes were recovered to normal conditions after 28 days of post-treatment (withdrawal study). Due to the Vepacide treatment, lung was more affected followed by liver and kidney. This study has indicated that these enzymes could be useful as biomarkers for the insult of any toxicant. Besides, they can also help in predictive toxicology.     

Effects of cadmium inhalation on mitochondrial enzymes in rat tissues

Pulmonary and extrapulmonary effects from a 2-h inhalation exposure to cadmium (850 micrograms Cd/m3) were studied in male rats. The effect of this chemical on mitochondrial enzyme activity in the lung, liver, kidney, and testis were investigated immediately after exposure and at 48, 144, and 336 h postexposure. In all tissues studied, mitochondrial citrate synthase activity was significantly increased immediately after the cessation of the exposure. This activity level began to decrease at 48 h postexposure. Succinic dehydrogenase activity was significantly decreased in the lungs and kidney at all periods tested, but increased activity was seen in the liver and testis. Cytochrome c oxidase activity in lungs and testis mitochondria was inhibited at all time periods studied. In the liver and kidney this activity was significantly increased immediately after the exposure ceased, and then a significant reduction began to appear at 48 h postexposure. This study demonstrates that inhaled cadmium, after deposition in the lungs, may alter various enzyme activities in other organs.     

CPU 86017, p-chlorobenzyltetrahydroberberine chloride, attenuates monocrotaline-induced pulmonary hypertension by suppressing endothelin pathway

AIM: To elucidate the involvement of the endothelin (ET) pathway in the pathogenesis of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and the therapeutic effect of CPU 86017 (p-chlorobenzyltetrahydroberberine chloride) in rats. METHODS: Rats were injected with a single dose (60 mg/kg, sc) of MCT and given CPU 86017 (20, 40, and 80 mg/kg-1/d-1, po) or saline for 28 d. The hemodynamics, mRNA expression, and vascular activity were evaluated. RESULTS: Right ventricular systolic pressure and central venous pressures were elevated markedly in the PAH model and decreased by CPU 86017. In the PAH group, the endothelin-1 (ET-1) in serum and lungs was dramatically increased by 54% (79.9 pg/mL, P<0.01) and 93% (166.2 pg/mL, P<0.01), and mRNA levels of preproET-1, eNOS, and iNOS also increased dramatically compared with control. Compared with PAH group, CPU 86017 decreased the content of ET-1 to the normal level in lung tissue, but was less effective in serum. The level of NO was significantly increased in CPU 86017 at 80 and 40 mg/kg-1/d-1 groups in tissue, whereas the difference in serum was not significant. A significant reduction in MDA production and an increase in the SOD activity in the serum and lungs was observed in all three CPU 86017 groups. CPU 86017 80 mg/kg-1/d-1 po increased the activity of cNOS by 33% (P<0.01). The up-regulation of eNOS and iNOS mRNA levels induced by MCT was significantly reversed in 3 CPU 86017 groups, and preproET-1 mRNA abundance was also reduced notably in CPU 86017 80 mg/kg-1/d-1 group vs the PAH group. The KCl-induced vasoconstrictions in the calcium-free medium decreased markedly in PAH group but recovered partially after CPU 86017 intervention. The constrictions in the presence of Ca(2+) was not improved by CPU 86017. The phenylephrine-induced vasoconstrictions in the calcium-free medium decreased markedly in PAH group but not recovered after CPU 86017 intervention. The constrictions in the presence of Ca(2+) completely returned to the normal after CPU 86017 intervention. CONCLUSION: CPU 86017 suppressed MCT-induced PAH mainly through an indirect suppression of the ET-1 system, which was involved in the pathogenesis of the disease.     

ACID AND ALKALINE PHOSPHATASE ACTIVITIES IN A NOVEL PHOSPHOROTHIONATE (RPR-11) TREATED MALE AND FEMALE RATS. EVIDENCE OF DOSE AND TIME-DEPENDENT RESPONSE

The effect of a novel phosphorothionate, the methyl ester of 2-butenoic acid-3-diethoxy phosphinothioyl (RPR-II) was studied on membrane bound target enzymes Acid (AcP) and Alkaline (AkP) Phosphatases in different tissues of male and female albino Wistar rats. Three sub-chronic doses 0.014 (low), 0.028 (medium) and 0.042 (high) mg/kg-1 were administered to the rats daily for a period of 90 days. The long term and repeated administration of RPR-II caused significant increase of AcP and AkP in serum and kidney (AcP), whereas these enzymes simultaneously decreased significantly in liver, kidney (female rat AkP) and lung tissues in both male and female rats after 45 and 90 days of treatment. However, the kidney AcP increased significantly in both the sexes which is suggestive of an increase in synthesis of this enzyme which may be an adaptive mechanism to the toxicant stress. The changes in serum, liver, kidney and lung of both male and female rats by this compound were statistically significant when compared with two way Anova showing that they are dose and time dependent. The alterations in male rats were statistically insignificant when compared with female rats showing no sexual dimorphism by this compound. Recovery was observed after 28 days of post treatment (withdrawal study) indicating reversal of the toxic symptoms once the toxicant is removed. High degree negative correlation was observed for serum versus liver and lung and in other cases substantial correlation was observed. The changes observed in these enzymes showed that liver was most susceptible followed by lung and kidney. There are marker enzymes and their increase in different tissues might be due to the increased permeability of plasma membrane or cellular necrosis, showing the stress condition of the treated rats. This investigation elucidates the effect of these biomarker enzymes which increased in blood, might be due to the necrosis of liver, kidney and lung tissues by this compound.     

Effects of cigarette smoke on rat lung and liver ornithine decarboxylase and aryl hydrocarbon hydroxylase activities and lung benzo(a)pyrene metabolism

The response of rat lung and liver ornithine decarboxylase (ODC) and aryl hydrocarbon hydroxylase (AHH) activities and lung benzo(a)pyrene (BP) metabolism was studied after exposing the rats to cigarette smoke. A close analysis of the time curves for ODC and AHH activities in rat lung and liver after a single exposure to cigarette smoke resulted in no clear correlation between the two parameters. Prolonged treatment (10 days) produced an increase in pulmonary ODC activity; hepatic ODC activity was unaffected. 10-day treatment was ineffective in raising AHH activity above values observed after a single treatment. BP metabolism, as determined in isolated perfused lungs by the appearance of organic- and water-soluble metabolites in the perfusion medium, the amount of covalently bound metabolites in lung tissue and the disappearance of unchanged 3-H BP from the perfusate, was markedly increased in response to cigarette smoke treatment. The data presented indicate that induction of AHH activity and increased metabolism of BP do not necessarily require a pre-existing increase in ODC activity.     

Distribution,excretion, and binding of radioactivity in the rat after intraperitoneal administration of the lung-toxic furan, [14C]4-ipomeanol

4-Ipomeanol [1-(3-furyl)-4-hydroxypentanone] is a poisonous metabolite produced in the mold-damaged sweet potato (Ipomoea batatas). In experimental animals the compound characteristically exhibits lung toxicity, producing prominent pulmonary edema and congestion. The distribution and excretion of radioactivity in rats after administration of [¹⁴C]4-ipomeanol has been studied. The toxin was given ip at doses of 2, 10, and 30 mg/kg. Approximately half of the administered radioactivity appeared in the urine within 2 hr, with only traces occurring in the feces and expired air. The greatest tissue concentration of radioactivity occurred in the lungs. Other organs showing significant concentrations were liver, kidney, and gastrointestinal tract. The maximal accumulation of activity occurred in the tissues within 0.5–1 h. The values declined over the next 1–2 hr, then reached a plateau representing residual activity. This residual activity is particularly high in lung, liver, and kidney, and represents the toxin or its metabolite(s) which has become tightly bound to tissue macromolecules. Binding occurs maximally in lung, and therefore may indicate that the binding phenomenon is involved in the toxic mechanism of 4-ipomeanol.