Activity of cathepsin B,D and L in rat cerebrum after cimetidine and famotidine administration

Cathepsins are lysosomal enzymes that are used a sensitive markers in various toxicological investigations. The purpose of this study was to evaluate and compare the influence of cimetidine and famotidine on the cerebral cortex, particularly on the activity of cortical cathepsin B, D and L in the frontal lobe of rat brain. The drugs were administered intraperitoneally, twice a day, for six weeks to male Wistar rats in two doses. The initial dose was 2.85 mg/kg for cimetidine and 0.285 mg/kg for famotidine. The second dose was 10 times higher. Control animals were injected with 0.9% NaCl. Half of the animals from each of the drug-treated and control groups were sacrificed on the 42nd day of the experiment. The remaining animals were raised for another 6 weeks without any xenobiotics, and sacrificed on the 84th day. The frontal lobe of the right cerebral hemisphere was taken for biochemical investigation. The activities of free and bound fractions of cathepsin B, D and L were evaluated spectrophotometrically in cortical homogenates. The activity of bound fraction of cathepsin D and L decreased significantly in animals exposed to the higher dose of cimetidine and sacrificed on the 42nd day. Also significant elevation of the free fraction of cathepsin L was noted in the same group of rats. Cathepsin activities were normalized during the next six weeks. No behavioural changes were noted among the observed animals. Unlike cimetidine, famotidine did not change profiles of the cerebral cathepsins.     

Influence of protein or cystein deficiency on hepatic subcellular distribution of methyl mercury in two rat strains

The influence of protein deprivation and cystein deficiency on the distribution of methyl mercury between 4 subcellular fractions of liver was studied in 2 rat strains (Wistar, strain R and Sprague-Dawley). Kept on a standard diet, the 2 strains showed a similar distribution pattern, with the highest mercury level found in the cytosol, followed by the mitochondrial, microsomal and nuclei fractions. The protein free diet caused on increase in the total amount of bound mercury in both strains, the greatest increase, being found in livers from strain R rats. The cystein deficient diet, on the other hand, gave rise to diverging results. Whereas the level of mercury bound to the subcellular fractions was increased in livers from strain R rats, it was markedly reduced in livers from Sprague-Dawley rats.     

Intravenous repeated-dose toxicity study of ZnPcS2P2-based-photodynamic therapy in Wistar rats.

The purpose of the current study was to investigate the potential repeated-dose toxicity of ZnPcP2S2-based photodynamic therapy (ZnPc-PDT) in Wistar rats. The animals were administered ZnPcS2P2 intravenously ten times successively every 4 d and irradiated with a 670 nm laser light for 6 min at subsequent 48 h and 72 h. At the end of the treatment period, 10 rats/sex/group were sacrificed, while 5 rats/sex/group were sacrificed after a two-week recovery period. During the test period, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, hematology, serum biochemistry, urinalysis, organ weights, gross findings and histopathology were examined. The association between the increased liver weight and hepatic spotty and lytic necrosis seen in high dose females corroborates the conclusion that high dose ZnPc-PDT could induce hepatic injury in Wistar rats and they are probably related to the abnormality of certain biochemical parameters of females in the high dose group. Furthermore, microscopic examination for the ZnPc-PDT groups shows the presence of some Kelly and khaki granules in Kupffer cells and endothelia of the livers, epithelia of the renal tubules, marginal sinus and medulla of the spleens, alveolar walls of the lungs, reticular cells and macrophages of the mesenteric lymph nodes, testicular Leydig cells, epididymal epithelial cells, endometrial stromal cells, and interstitial cells and corpora lutea of the ovaries from all or most of the animals. There were no adverse effects on mortality, clinical signs, food and water consumption, ophthalmoscopy, uranalysis, hematology, serum biochemistry, body weights and necropsy findings in control, low and mid dose groups. Based on these results, it was concluded that the intravenous repeated-dose of ZnPcP2S2-PDT induced the abnormalities of liver weights, hepatic biochemistry and histopathology, and pigmentation in the several important organs in Wistar rats at 4 mg kg(-1) d(-1). The target organ was determined to be liver (and spleen perhaps), but this was not so obvious in males. The no-observed-adverse-effect level (NOAEL) was considered to be 1.0 mg kg(-1) for both sexes.     

Receptor-mediated introduction of pepstatin-asialofetuin conjugate into lysosomes of rat hepatocytes

Pepstatin was linked through a carboxyl group to asialofetuin (PS-ASF). An analysis by separation of hepatocytes from nonparenchymal cells showed that PS-ASF was taken up by hepatocytes, following intravenous injection into rats. After the injection of PS-ASF, pepstatin concentration in the liver reached a maximum at 2 h and then decreased. In an analysis by differential centrifugation of the liver homogenate from rats injected with PS-ASF, pepstatin showed a lysosomal type subcellular distribution pattern. Isolation studies of tritosomes clearly demonstrated the exclusive accumulation of pepstatin within the lysosomes of livers from rats given PS-ASF (at 2 h after administration). Pepstatin contained in tritosomes was in a free form, as determined by column chromatography of Sephadex G-15. The activity of cathepsin D in the livers was markedly inhibited in rats given PS-ASF. However, the treatment of rats with PS-ASF had no effect on the hepatic lysosomal degradation of endocytosed FITC-labeled asialofetuin (FITC-ASF). Introduction of PS-ASF into the hepatocytes was followed by the immediate and time-dependent excretion of free pepstatin into the bile. Quantification of pepstatin excreted into the bile revealed that the biliary excretion route can account for the disappearance of pepstatin from the liver.     

Characterization of porcine adrenocortical lysosomes

Porcine adrenocortical lysosomes were characterized by differential centrifugation, acid hydrolase contents, latency of cathepsin D, release of bound acid hydrolases in soluble form, and isopycnic density gradient centrifugation. Cathepsins D and B, beta-N-acetylglucosaminidase, beta-galactosidase and arylsulphatase were found exclusively in the lysosomes, while alpha-mannosidase and beta-glucuronidase were in both the lysosomal and microsomal fractions. The activity of cathepsin D was remarkably high, amounting to more than 6 times that in porcine liver and to more than 10 times that in liver of Sprague-Dawley rats in terms of units per g wet tissue. Porcine adrenocortical lysosomes showed a modal isopycnic density value of 1.155, but mitochondria a value of 1.145. The validity of these values was studied by investigating the possibilities of agglutination of organelles, damage to lysosomal membranes, disruption of mitochondria due to the hydrostatic pressure and by applying the same procedures of isopycnic centrifugation to hog and rat livers. After these validity tests, porcine adrenocortical lysosomes were concluded to be unique in their strikingly high content of cathepsin D as well as in their low modal isopycnic density which is very close to that of porcine adrenocortical mitochondria.     

Distribution of glucose-6-phosphatase activity in normal,hyperplastic, and preneoplastic rat liver

The significance of glucose-6-phosphatase (G6P) expression by bile duct-like cells proliferating during hepatocarcinogenesis in the histogenesis of hepatocellular carcinoma is not clear. To this end, we measured the histochemical and biochemical activity of G6P in normal rat liver, and in rat livers in which bile duct-like proliferation was induced by either hyperplastic (bile duct ligation for 14 days or feeding alpha-naphthylisothiocyanate for 28 days) or neoplastic (feeding a choline-devoid diet containing 0.1% ethionine for 60 days) regimens. In normal, hyperplastic, and preneoplastic livers, G6P histochemical activity was confined to the hepatocytes; proliferated bile duct-like cells, like normal bile ducts, did not display visible G6P staining. When the enzyme activity was determined biochemically, however, hydrolysis of glucose-6-phosphate was observed in both parenchymal and nonparenchymal liver cells isolated from all experimental animals. In elutriated nonparenchymal fractions, G6P activity was directly proportional to the number of cells positive for gamma-glutamyl transpeptidase and cytokeratin no. 19 (markers of bile duct cells) and inversely proportional to the number of cells positive for vimentin (marker of mesenchymal cells). These results indicate that, while by light microscopy hepatic G6P histochemical activity is detectable only in the hepatocytes, the biochemical activity is also expressed in proliferating bile duct-like cells. However, the nonparenchymal activity is observed during both neoplastic and hyperplastic liver growth, thus indicating that the presence of this enzyme in bile duct-like cells proliferating during hepatocarcinogenesis should not necessarily be construed as supporting their stem cell nature nor their neoplastic commitment.     

Distribution of glucose-6-phosphatase activity in normal, hyperplastic, and preneoplastic rat liver.

The significance of glucose-6-phosphatase (G6P) expression by bile duct-like cells proliferating during hepatocarcinogenesis in the histogenesis of hepatocellular carcinoma is not clear. To this end, we measured the histochemical and biochemical activity of G6P in normal rat liver, and in rat livers in which bile duct-like proliferation was induced by either hyperplastic (bile duct ligation for 14 days or feeding alpha-naphthylisothiocyanate for 28 days) or neoplastic (feeding a choline-devoid diet containing 0.1% ethionine for 60 days) regimens. In normal, hyperplastic, and preneoplastic livers, G6P histochemical activity was confined to the hepatocytes; proliferated bile duct-like cells, like normal bile ducts, did not display visible G6P staining. When the enzyme activity was determined biochemically, however, hydrolysis of glucose-6-phosphate was observed in both parenchymal and nonparenchymal liver cells isolated from all experimental animals. In elutriated nonparenchymal fractions, G6P activity was directly proportional to the number of cells positive for gamma-glutamyl transpeptidase and cytokeratin no. 19 (markers of bile duct cells) and inversely proportional to the number of cells positive for vimentin (marker of mesenchymal cells). These results indicate that, while by light microscopy hepatic G6P histochemical activity is detectable only in the hepatocytes, the biochemical activity is also expressed in proliferating bile duct-like cells. However, the nonparenchymal activity is observed during both neoplastic and hyperplastic liver growth, thus indicating that the presence of this enzyme in bile duct-like cells proliferating during hepatocarcinogenesis should not necessarily be construed as supporting their stem cell nature nor their neoplastic commitment.     

壮肝逐瘀煎对肝纤维化大鼠肝脏Fas/FasL表达的影响

目的:研究壮肝逐瘀煎对肝纤维化(HF)大鼠肝脏肝星状细胞(HSC)的凋亡因子Fas/FasL表达的影响,探讨该方抗HF的作用机制。方法:58只SD大鼠随机取14只作为正常对照组,正常饲养。剩余大鼠采用CCl4复合因素法进行HF造模,实验第4周末随机处死造模大鼠4只,证实HF形成。其余随机分为病理模型组、壮肝逐瘀煎组、秋水仙碱组及大黄蛰虫丸组,每组10只。病理模型组给予生理盐水灌胃处理,其他3组分别予对应药物灌胃处理。治疗第6周末,处死所有大鼠,获取肝组织,HE染色光镜观察肝组织结构变化,免疫组化染色分析Fas、FasL分布。结果:与病理模型组大鼠比较,壮肝逐瘀煎治疗组肝小叶结构趋于正常,纤维间隔明显变薄,肝组织Fas、FasL的表达显著表达显著减少(P0.01)。结论:壮肝逐瘀煎能够明显改善HF大鼠肝脏的病理变化,具有明显的抗HF作用,其作用机制可能与壮肝逐瘀煎能调控HSC中凋亡因子Fas/FasL的表达有关。     

Studies on peroxisomes. V. Effect of ethyl p-chlorophenoxyisobutyrate on the centrifugal behavior of rat liver peroxisomes.

After Wistar male rats had been fed on a diet containing 0.25% of ethyl p-chlorophenoxyisobutyrate (CPIB) for 28 days, changes in the enzyme activities and centrifugal behavior of rat liver peroxisomes were investigated. (1) Compared with control rats fed on the basal diet, the catalase [EC 1.11.1.6] activity of rat livers after the administration of CPIB increased about 2.5-fold, while urate oxidase [EC 1.7.3.3] activity did not change significantly. Though D-amino acid oxidase [EC 1.4.3.3] activity markedly decreased to approximately one-sixth of the control, the activity of L-alpha-hydroxy acid oxidase [EC 1.1.3.15], a flavin enzyme like D-amino acid oxidase, was not affected significnatly after the administration of CPIB. (2) When the hepatic cells of CPIB-treated rats were fractionated by differential centrifugation, most of the increase of catalase activity appeared in the supernatant fraction. A decrease in the hepatic D-amino acid oxidase activity of CPIB-treated rats was observed in all the fractions. As for the subcellular distribution of the particle-bound enzymes, the specific activities of both catalase and urate oxidase of CPIB-treated rat livers were higher in the light mitochondrial fraction than in other fractions. (3) Sedimentation patterns in a sucrose density gradient did not show any difference between normal peroxisomers, and CPIB-treated ones. (4) In the case of CPIB-treated rats, studies of their sedimentation patterns by Ficoll density gradient centrifugation showed two main particulate peaks containing both catalase and urate oxidase, although only a single peak was observed in the case of control rats.     

Activity of cathepsins in rat's spleen due to experimentally induced pancreatitis.

The aim of this study was to establish and quantify the changes of the level of cathepsin B, D and L in the spleen during experimental pancreatitis. The experiment was carried out in 115 male Wistar rats, randomly divided into three groups: intact (n = 15), injected with 0.9% NaCl solution into the common bile pancreatic duct (n = 50) and injected with 5% sodium taurocholate into this duct to induce acute pancreatitis (n = 50). After 2, 6, 12, 24 and 48 hours rats were anaesthetised, and blood was taken for amylase determination from the heart, and the spleen was removed. Alpha-amylase level in the blood serum samples was measured by enzymatic method. Cathepsin activity was established by spectrophotometric methods using substrates which form coloured complexes when they react with these proteases. The specific free fraction activity of cathepsin B, D and L in the spleen changed during the course of experiment, but there was no correlation between their activity and the intensity of pancreatitis established by serum amylase level.     

Distribution and subcellular localization of a hepatic proliferation inhibitor in rat liver

The subcellular and intralobular distributions of a protein which specifically inhibits the proliferation of normal liver cells were determined in rat liver, using a combination of immunological and biochemical techniques. The IgG fraction from an antiserum raised against the hepatic proliferation inhibitor was isolated by protein A-Sepharose CL-4B chromatography and shown to be highly specific for the antigen using electroimmunodiffusion and affinity chromatography. To determine the intracellular location of the inhibitor, subcellular fractions were prepared from adult rat livers by differential centrifugation. The cytoplasmic fraction contained the biologically active cytostatic inhibitor, whereas the nuclear and mitochondrial fractions were inactive. Cytoplasmic localization of the hepatic proliferation inhibitor was further confirmed by anion exchange high performance liquid chromatography and by double immunodiffusion with the anti-hepatic proliferation inhibitor IgG. When liver sections were subjected to histochemical staining mediated through the immune IgG and an avidin-biotinylated horseradish peroxidase complex, the parenchymal liver cells were stained, but endothelial and connective tissue cells were not. Although some staining was evident throughout the liver parenchyma, the most intensely stained cells were located in the centrilobular region. Moreover, an age-dependent increase in the staining intensity and/or in the number of cells containing the proliferation inhibitor was observed. Preliminary experiments showed that little, if any, staining occurred in hepatocellular carcinoma cells. This highly specific IgG can be used to monitor alterations in the content and location of hepatic proliferation inhibitor in proliferative disorders of the liver.     

Effect of probiotic fermented milk and chlorophyllin on gene expressions and genotoxicity during AFB₁-induced hepatocellular carcinoma

The aim of this study was to investigate the chemopreventive effect of probiotic fermented milk and chlorophyllin on aflatoxin B? (AFB?) induced hepatocellular carcinoma. In vivo trials were conducted on 200 Wistar rats allocated to eight groups. Rats in the positive control group were given intraperitoneal injection of aflatoxin B? at 450 μg/kg body weight twice a week for 6 weeks. The rats were sacrificed and dissected at 25th week of the experiment, and comet assay was carried out in hepatic cells to assess the genotoxicity or DNA damage. The tumour incidence was decreased by approximately one-third than AFB? control group. The expression of c-myc bax, bcl-2, cyclin D1, p53 and rasp-21 genes was also studied. A significant (P<0.05) reduction in DNA damage was observed in probiotic fermented milk with chlorophyllin group as compared to aflatoxin B? control group. The c-myc, bcl-2, cyclin D1 and rasp-21 level was found to be highest in AFB? control group as compared to the treatment group. The results advocate the enhanced protective potential of probiotic fermented milk and chlorophyllin against AFB?-induced molecular alterations in hepatic cells during carcinogenesis.     

Cathepsin K and matrix metalloprotease activities in bone tissue of the OXYS rats during the development of osteoporosis

The activity of osteoclast-specific cysteine protease, cathepsin K, and matrix metalloproteases (MMPs) has been investigated in bone tissue of senescence-accelerated OXYS rats and in Wistar rats. At the age of 3 month (the period preceding manifestation of osteoporosis in OXYS rats) cathepsin K activity was higher whereas MMP activity was lower in Wistar rats. At the age of 14 months Wistar rats cathepsin K activity increased and MMP activity decreased. The age-related changes in bone cathepsin K and MMP activity of OXYS rats had opposite direction. Thus, despite of marked manifestations of osteoporosis previously found by us in OXYS rats (the decrease in mineralization density of the bone tissue and its resorption) no interstrain differences in cathepsin K and MMPs were found between Wistar and OXYS rats. Activity of a universal protease inhibitor, α₂-macroglobulin, was higher in serum of 14-month old OXYS rats than in Wistar rats of the same age. The role of cathepsin K activation in resorption of bone tissue in the development of osteoporosis in senescence-accelerated OXYS rats is discussed.     

Strain differences in purified rat hepatic 3 alpha-hydroxysteroid UDP-glucuronosyltransferase.

Qualitative and quantitative differences of purified hepatic 3 alpha-hydroxysteroid UDP-glucuronosyltransferase were investigated in Wistar and Sprague-Dawley rats. Individual differences in the glucuronidation rate of androsterone and chenodeoxycholic acid were observed in hepatic microsomal fractions from Wistar but not Sprague-Dawley rats. No individual variation was observed in the glucuronidation of testosterone, p-nitrophenol or oestrone. The 3 alpha-hydroxysteroid UDP-glucuronosyltransferases from livers of Wistar and Sprague-Dawley rats were isolated and highly purified by using Chromatofocusing and affinity chromatography. The amount of 3 alpha-hydroxysteroid UDP-glucuronosyltransferase in the liver of Wistar rats exhibiting low rates for androsterone glucuronidation is about 10% or less than that found in hepatic microsomal fractions obtained from Wistar rats having high rates for androsterone glucuronidation. The apparent Km for androsterone with purified 3 alpha-hydroxysteroid UDP-glucuronosyltransferase from Wistar rats with high glucuronidation activity (6 microM) was not different from that observed for the enzyme purified from Sprague-Dawley animals, whereas that for the enzyme purified from Wistar rats with low glucuronidation activity was substantially higher (120 microM). Despite the differences in apparent Km values for androsterone, the apparent Km for UDP-glucuronic acid (0.3 mM) was not different in the different populations of rats.     

Effects of photodynamic treatment on biological antioxidant systems in rats

Effects of photodynamic treatments on inherent antioxidant metabolites and cellular defence enzymes have been investigated in rats. Wistar rats were grouped into untreated controls, light controls, hematoporphyrin derivative (Hpd) (treated with 5 and 10 mg Hpd/kg body weight and kept in dark) and sets treated with both Hpd and red light (dose 172 and 344 j/m2 ). After 2, 24, 48 and 72 hr of Hpd injection the rats sacrificed, livers quickly excised to analyze Hpd uptake, activities of enzymes like catalase, GSH-Px and antioxidants like GSH, vitamin A, vitamin E and vitamin C. The results showed that the loss of Hpd from liver as a function of post- injection time was non- linear. An increased generation of lipid radicals was observed in the groups treated with 5 mg Hpd and higher dose of light and in groups treated with 10 mg Hpd at both the doses of light. Combination of light and Hpd reduced hepatic GSH content with a concomitant reduction in GSH-Px. At higher doses of Hpd and light, there was a significant reduction in hepatic vitamin A levels. Combination of Hpd and light in all doses reduced vitamin E content in liver. The decreased biological antioxidant contents and GSH-Px may be attributed to their utilization for the scavenging of free radicals generated by Hpd and light in tissues. However, no change in catalase activity and vitamin C content in liver was noted in experimental rats. The results suggest that exposure to higher doses of Hpd with light alters oxidant stress system and TBARS content in rat.     

Localization of cathepsin D in rat liver. Immunocytochemical study using post-embedding immunoenzyme and protein A-gold techniques

Light and electron microscopic localization of cathepsin D in rat liver was investigated by post-embedding immunoenzyme and protein A-gold techniques. By light microscopy, cytoplasmic granules of parenchymal cells and Kupffer cells were stained for cathepsin D. Weak staining was also noted in sinusoidal endothelial cells. In the parenchymal cells many of positive granules located around bile canaliculi. In the Kupffer cells and the endothelial cells, diffuse staining was noted in the cytoplasm in addition to granular staining. By electron microscopy, gold particles representing the antigenic sites for cathepsin D were seen in typical secondary lysosomes and some multivesicular bodies of the parenchymal cells and Kupffer cells. The lysosomes of the endothelial cells and fat-storing cells were weakly labeled. Quantitative analysis of the labeling density in the lysosomes of these three types of cells demonstrated that the lysosomes of parenchymal cells and Kupffer cells are main containers of cathepsin D in rat liver. The results suggest that cathepsin D functions in the intracellular digestive system of parenchymal cells and Kupffer cells but not so much in that of the endothelial cells.     

不同剂量玛咖对力竭运动致大鼠运动性低血糖的保护作用

目的：探讨不同剂量玛咖对力竭运动致大鼠运动性低血糖的保护作用。方法：采用递增负荷力竭游泳训练的方法建立运动性低血糖动物模型。55只42 d龄雄性Wistar大鼠随机分为5组：①静止对照组（C组）,②运动对照组（M组）,③~⑤运动+低、中、高剂量玛咖组（LM I、LM Ⅱ,LM Ⅲ组）,每组10只（剔除不符合实验要求的大鼠5只）。每天灌胃（ig）1次,LM各组灌胃玛咖的剂量为0.2,0.4,1.2 g/kg体重,灌胃体积为5 ml/kg体重,C、M组灌胃等体积生理盐水。运动大鼠采用递增负荷力竭游泳训练42 d,42 d力竭游泳训练后,测定体重、力竭游泳时间,取血、肝脏及深层股四头肌检测相关生化指标。结果：与C组比较,M组体重、血糖水平、肌糖原与肝糖原含量、肝细胞磷酸烯醇式丙酮酸羧激酶（phosphoenol pyruvate carboxy kinase,PEPCK）表达、肝细胞阳性染色累计吸光度均值等均明显降低（P<0.05或P<0.01）;力竭游泳时间无明显差异;血乳酸含量明显升高（P<0.01）。与M组比较,LM各组体重、血糖水平、肌糖原与肝糖原含量、肝细胞PEPCK表达、肝细胞阳性染色累计吸光度均值等均明显升高（P<0.05或P<0.01）,力竭游泳时间明显延长（P<0.01）,血乳酸含量明显降低（P<0.01）。与LM I组比较,LMⅢ组体重无明显差异,LM Ⅲ组血糖水平、肌糖原与肝糖原含量、肝细胞PEPCK表达、肝细胞阳性染色累计吸光度均值等均明显升高（P<0.05）,力竭游泳时间明显延长,血乳酸含量明显降低（P<0.05）。结论：高剂量玛咖可有效抑制和延缓长时间、大负荷运动导致的运动性低血糖和运动性疲劳的发生与发展,其机制可能与优化肌糖原和肝糖原的储备量及上调糖异生限速酶PEPCK的表达,提高PEPCK活性,促进糖异生有关。     

Preservation of hepatic cell integrity by aprotinin in hypoxia

Perfused cat livers subjected to 2.5 hr of hypoxia exhibited dramatic increases in perfusate cathepsin D and lactic acid dehydrogenase (LDH) activities, amino nitrogen concentrations, and a 60% depression in the clearance rate of carbon particles by the reticuloendothelial system (RES). Addition of aprotinin (250 KIU/ml) to the perfusate prior to hypoxia prevented the increases in circulating cathepsin D, LDH, and amino-nitrogen observed at 150 minutes. In addition, aprotinin prevented the reduction in carbon clearance during severe hypoxia. However, aprotinin had no effect on the percent free cathepsin D activity indicating that this agent did not directly prevent increases in lysosomal fragility occurring in response to hypoxia. Thus, addition of pharmacologic doses of aprotinin to the perfusate protected RES cells, and markedly reduced the release of cytoplasmic and lysosomal enzymes. The prevention of cell membrane dissolution appears to be a critical factor in hepatic preservation, and may be related to the inhibition of proteolysis by aprotinin. These effects may help explain the therapeutic effectiveness of this agent in shock and in myocardial ischemia.     

Influence of glucocorticoid on the metabolism of aldosterone in the isolated perfused rat liver and kidney.

The effect of glucocorticoid deficiency and excess on the extraadrenal metabolism of D-[4-14C]aldosterone (at 4 nM) was studied by radioimmunoassay and by high-performance liquid chromatography in the isolated perfused liver and kidney of adult Wistar rats. Bilateral adrenalectomy was performed 3 weeks before experiments. In nonadrenalectomized rats, 0.3 mg/kg/day dexamethasone was continuously infused subcutaneously for 1 week before experiments. Adrenalectomy did not affect hepatic or renal metabolism of aldosterone. Dexamethasone treatment did not change the renal handling of aldosterone. However, the hepatic clearance of aldosterone was 19% lower (P less than 0.05) in livers of dexamethasone treated rats than in livers of normal rats. After 5 minutes, perfusate [4-14C]aldosterone metabolites were lower in livers of dexamethasone-treated than in livers of normal rats (P less than 0.05). Similar perfusate levels were then obtained. Radiometabolite peaks with similar relative retention times were found in the hepatic perfusate of all groups. However, the ratio between circulating polar metabolites of aldosterone and the metabolites less polar than tetrahydroaldosterone, after 5 and 15 minutes, was highest in livers of dexamethasone-treated rats. Biliary elimination of 14C was similar in all groups. Significant amounts of conjugated tetrahydroaldosterone were only excreted in the bile of dexamethasone-treated rats. In conclusion, glucocorticoid excess reduced the hepatic clearance of aldosterone and changed the pattern of the hepatic metabolites of aldosterone both in circulation and in bile.     

Effect of hypothermia on subcellular distribution and various physico-chemical properties of cathepsin D in rat brain

The total cooling ef rats down to the rectal temperature 30 degrees and 20 degrees C does not change significantly the ratio of the relative specific activity of cathepsin D in subcellular fractions of the rat brain. The gel chromatographic analysis of heterogeneity of cathepsin D molecular forms in subcellular fractions established the presence of a high-molecular (in the fractions of lysosome and microsome mitochondria) and a low-molecular (in the fractions of lysosome and cytosol mitochondria) enzyme forms. Under hypothermia (20 degrees C) in the brain cytosol fraction there arises a minor zone of the cathepsin D activity corresponding to the high-molecular enzyme form.