ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb03406.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The effect of methyl mercury (MeHg) and triethyllead (Et3Pb) on the membrane bound SH‐enzymes Na+K+ATPase and pyruvate dehydrogenase (PDH) was studied in relation to the effect on the galactosyl ceramide sulfotransferase (CST) and to morphological changes in glioma C6cells. Two‐day‐old cultures were incubated for 1 or 20 hrs with 5–30 μg MeHgCl and 2–8 μg Et3PbCl/mg cell protein. The results show that both compounds induced morphological changes and a reduction of CST activity at growth inhibitory concentrations. A less marked reduction of Na+K+ATPase was induced with increasing exposure time only in MeHgCl treated cultures, and PDH activity was not affected by either of the compounds under the experimental conditions. Thus, an interference with Na+K+ATPase and PDH activities do not appear to be a primary effect of MeHg and Et3Pb i

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01055.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The electrophysiological and mechanical effects of prenalterol on the isolated guinea pig atrial trabeculae and papillary muscles were compared with those of terbutaline and isoprenaline. Isoprenaline was the most potent of the drugs tested on all parameters studied. Prenalterol, on the other hand, failed to induce any changes in the atrial action potentials. The action potential duration was shortened in the atrial trabeculae by terbutaline and isoprenaline. All three substances shortened the action potential in the papillary muscles. In addition, isoprenaline increased the plateau height, and like terbutaline, increased the rate of repolarization during phase 3. Neither prenalterol nor terbutaline changed the effective refractory period in the atrial trabeculae whereas isoprenaline shortened it. All three substances shortened this parameter in the papillary muscles. The developed force and the rate of developed force were increased by all three substances. In addition. the total twitch duration was decreased.

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01056.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The distribution of iron‐59 in blood at various time intervals was studied in sham and partially‐hepatectomized rats after a single intravenous injection of59Fe (III) citrate. A significant difference was observed in the rate of disappearance and reappearance of iron‐59 in circulation. Administration of cadmium and manganese at a concentration of 0.5 and 2 mg/kgb.wt., respectively, did not cause any significant change in this pattern. A significant decrease in iron‐59 incorporation in the liver of hepatectomized rat was produced by cadmium while manganese had no

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01057.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:In order to determine the effect of pH changes of water on the metabolism of xenobiotics, fish were exposed for 8 hours to the acidic water (pH 3). Two fish species were used, lavaret, (Coregonus lavaretus), and splake (Salvelinus fontinalis X Salvelinus namaycush). The metabolism of xenobiotics was monitored by analyzing aryl hydrocarbon hydroxylase, epoxide hydrase and ethoxycoumarin O‐deethylase activities as well as the activity of UDPglucuronosyltransferase using both p‐nitrophenol and 4‐methylumbelliferone as aglycones. A difference was found between species in measured basal activies. The aryl hydrocarbon hydroxylase activity, epoxide hydrase activity and ethoxycoumarin O‐deethylase activity were higher in the splake than in the lavaret, No clearcut differences were detected in UDPglucuronosyltransferase activities. When fish were exposed to water at pH 3, the aryl hydrocarbon hydroxylase acivity and epoxide hydrase activity in the splake were lower than in the control fish. The ethoxycoumarin O‐deethylase activity was higherin the lavarets at pH 3 than in the controls. The UDPglucuronosyltransferase activity was higher in both splakes and lavarets exposed to pH 3 when analyzed after trypsin digestion of microsomes and with 4‐methylumbelliferone as

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01058.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:To elucidate the validity of the indirect method of following insulin absorption from the subcutaneous tissue, i.e. external counting of injected 125‐I insulin, the disappearance of 125‐I NPH insulin from subcutaneous tissue was measured by a biotelemetric method (external measurement of radioactivity) and by direct determination of radioactivity and insulin in subcutaneous tissue extracted one to 300 min. after injection of 8 units 125‐I NPH porcine insulin, 5 mm beneath the surface of the skin in 6 anaesthesized pigs. Furthermore. the appearance of insulin in arterial plasma was measured after inhibiting the endogenous insulin secretion of the pigs by epinephrine and propanolol. The disappearance of radioactivity measured continuously for 5 hours was of first order kinetics with t1/2 = 462 ± 36 min. (mean ± S.E.M.). The half‐life of the injected depot of radioactivity (t1/2) demonstrated a large intra‐ as well as interindividual variation as seen in diabetics. In tissue extracts a highly significant (2P<0.001) correlation was found between radioactivity and insulin (r = 0.93), indicating the radioactivity to be representative of insulin. During gel chromatography on Sephadex G 50 M only one peak of radioactivity was seen in all tissue extracts. 300 min. afterNPH‐insulin injection, however, the specific radioactivity of insulin was significantly higher (2 P<0.05) than in tissue extracts sampled one min. after NPH insulin injection, indicating a slight accumulation of non‐immunoreactive insulin degradation products. A fair correlation (r = 0.75, 2 P<0.05) was seen between the disappearance of externally measured radioactivity or insulin from tissue extracts and the appearance of insulin in plasma. It is concluded that the insulin absorption coefficient is a relevant and biologically sensible expression of ins

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01059.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Six thioureas: 1,3‐diphenylthiourea (DPTU), 1,3‐dibutylthiourea (DBTU), tetramethylthiourea (TEMTU), trimethylthiourea (TRIMTU), 1,3‐diethylthiourea (DETU), and 1,3‐ethylenethiourea(ETU), were tested, in addition to carbon disulfide, on three day chicken embryos for embryotoxicity. The parameters measured were early deaths, recorded within two days of injection, late deaths of malformed embryos, late deaths of non‐malformed embryos, and malformed survivors. The order of total embryotoxicity decreased as follows DBTU>DPTU>TEMTU>TRIMTU>DETU>ETU. The range for ED50 values for total embryotoxicity was from 0.28 (DBTU) to 4.5 (ETU) μmol/egg. DBTU caused early deaths but no malformations. TEMTU and DPTU were the most potent

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01060.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The exposure of rats to SO2(10 p.p.m.) for one hour daily for 30 days caused depletion of total lipids in all brain areas. The contents of phospholipid were elevated in cerebellum and brain stem, but were depleted in cerebral hemisphere. Cholesterol levels showed an increase in various brain regions. On the other hand, gangliosides were increased in cerebellum and brain stem, but were decreased in cerebral hemisphere. Interestingly, cholesterol/phospholipid ratio was increased in different regions of the brain. Lipase activity was elevated in cerebral hemisphere. Lipid peroxidation showed marked increment in whole brain and in all the brain areas studied. The results suggest that SO2‐exposure induces degradation of lipids. Interestingly, the lipid contents are affected differentially in the various parts of the brai

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01061.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The adenylate cyclase in two particulate preparations from rat brain, a homogenate from caudate nucleus (CN‐homogenate) and a synaptosomal plasma membrane fraction (SPM‐fraction) from whole rat brain was investigated. Stimulation of the enzyme by dopamine and prostaglandins E1and E2was found in the CN‐homogenate while only a weak prostaglandin E1and E2stimulation and no dopamine stimulation could be found in the SPM‐fraction. Guanyl‐5′‐yl‐imidophosphate (GppNHp) and NaF could stimulate the adenylate cyclase in both preparations. Morphine up to 10–5M altered neither the basal enzyme activity nor any of the stimulated

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01062.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Experiments showed that the cyclic AMP (cAMP) fraction isolated by alumina or Dowex 50/ alumina chromatography from brain adenylate cyclase reaction mixtures contained “P radioactivity 10–12 times in excess of that which could be accounted for by determination of cAMP using binding assays. No such discrepancy was found when lysed turkey erythrocytes were assayed. This indicated that special precautions must be taken for the purification of32PcAMP from brain adenylate cyclase assays due to the formation of32P‐labelled contami

ISSN:0001-6683    

DOI:10.1111/j.1600-0773.1982.tb01063.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY