ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00959.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00960.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The aim of this study was to examine the modulating role of presynaptic α2‐adrenoceptors on transmitter release from vascular sympathetic neurones. This was done by examining the influence of removal of inactivation pathways on the effect of α‐adrenoceptor antagonists on the release of transmitter from noradrenergic neurones. The rabbit main pulmonary artery preloaded with3H‐noradrenaline (3H‐NA) was used. The artery was stimulated with 300 pulses at various frequencies (1, 3, 10 and 30 Hz). Pargyline (3 × 10−4M) increased the stimulation‐evoked3H‐overflow at 1 and 3 Hz and decreased it at 30 Hz. U‐0521 (3′,4′‐dihydroxy‐2‐methylpropiophenone; 3 × 10−6M) enhanced the overflow at 1 Hz and had no effect at 3–30 Hz. Corticosterone (4 × 10−5M) did not alter the stimulation‐evoked3H‐overflow at 1–30 Hz. Cocaine (3 × 10−6M) enhanced the3H‐overflow slightly at 1–30 Hz. At 3 × 10−5M, cocaine enhanced3H‐overflow at 1 Hz and reduced it at 30 Hz. Neither corticosterone (4 × 10−5M) nor propranolol (10−7M) modified this effect of cocaine. Propranolol (10−7M) alone decreased the3H‐overflow at 30 Hz and had no effect at 1–10 Hz. Phenoxybenzamine (10−6M) and chlorpromazine (3 × 10−6M) potentiated the stimulation‐evoked3H‐overflow at 1–30 Hz. Phentolamine (10−6M) decreased the3H‐overflow at 1 Hz and enhanced it at 3–30 Hz. Rauwolscine (10−6M) enhanced the stimulation‐evoked3H‐overflow maximally at 10 Hz and had no effect at 1 and 30 Hz. Cocaine (3 × 10−5M), cocaine (3 × 10−5M) + corticosterone (4 × 10−5M), pargyline (3 × 10−4M) and U‐0521 (3 × 10−6M), but not corticosterone (4 × 10−5M), increased the rauwolscine‐induced enhancement at 1 and 3 Hz, but had no influence at 10 and 30 Hz. It is concluded that at a low frequency (1 Hz) of nerve stimulation, inhibition of either neuronal uptake, extraneuronal uptake, monoamine oxidase (MAO) or catechol‐O‐methyltransferase (COMT) causes an enhancement in transmitter overflow that is due to removal of inactivation pathways. The enhancement is not mediated via facilitatory β‐adrenoceptors. At higher frequencies (3–30 Hz) inhibition of either neuronal uptake or MAO causes a sufficient amount of transmitter in the neuromuscular gap to activate the presynaptic α‐adrenoceptor mediated negative feed‐back system causing a decrease in transmitter release. α‐ Adrenoceptor antagonists enhance the stimulation‐evoked release of3H‐NA only

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00961.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The effect of furosemide on vascular smooth muscle was studied on segments of rabbit blood vessels. Furosemide (20 μg/ml) induced small (3–4%) decreases in resting tension whereas nitroglycerin (0.5 μg/ml) induced decreases from 8 to 13%. The addition of albumin (45 g/l) abolished the furosemide response whereas the nitroglycerin response was unaffected. Similarly the pronounced effect of nitroglycerin on electrically evoked contractions was unaffected by the presence of albumin whereas the furosemide effect was weakened by albumin. The biologically determined free fraction of furosemide increased with increasing drug concentrations from 13% at 16 μg/ml to 35% at 256

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00962.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:Hepatic damage was induced in phenobarbitone pretreated male Fischer 344 rats by the administration of 1 % halothane in 14% oxygen for either 1 or 2 hours. Ethane production during the exposure period was not significantly different between the halothane and non‐halothane exposed groups. Animals were sacrificed 1, 2, 6 and 24 hrs from commencement of anaesthesia and the hepatic microsomal fraction analyzed for diene conjugates, lipid hydroperoxides, total lipid content and fatty acid composition. Animals exposed to halothane and sacrificed at 2 and 24 hrs had significantly elevated levels of diene conjugates (P<0.05), while lipid hydroperoxide concentration and serum alanine aminotransferase increased in only those animals sacrificed at 24 hrs. Alterations in total lipid content and hepatic microsomal fatty acid composition were not observed in animals sacrificed after 1 and 2 hrs. A significant reduction in total lipid and arachidonic acid content occurred only in those animals sacrificed 24 hrs after exposure, however a concomitant increase in the saturated fatty acid fraction was not observed. It is proposed that alterations in fatty acid compositionin vivoand evidence of lipid peroxidation occur as a result of cell death rather than an initiating event in halothane induced hepatic necrosis in rat

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00963.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:Thymus anlagen from 11‐day‐old chick and 14‐day‐old turkey and duck embryos were cultured in media containing 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD) for 5 days. The maximal TCDD‐induced decrease in lymphoid cell number of chick embryo thymus (to about 60% of the control number) occured at concentrations of 10−10M and above. To produce the same effect on lymphoid cell number in the cultures of thymus anlagen from turkey and duck embryos, about a 100‐fold higher concentration of TCDD was needed. The toxicity of the TCDD congeners 3,3′4,4′‐tetrachloroazoxybenzene (TCAOB) and 3,3′,4,4′‐tetrachlorobiphenyl (TCB) to embryonic chicken thymus was testedin vitroandin ovo.In chick embryo thymus cultures, TCAOB and TCB were about two orders of magnitude less toxic than TCDD. Injection of TCAOB and TCB into chicken eggs preincubated for 11 days resulted in a dose‐dependent decrease in thymic lymphoid cell number 5 days later, declining to about 14% of the controls at 10 μg TCAOB/kg egg. The ED50value was estimated to be 3.6 and 60 μg/kg

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00964.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The UDP‐glucuronyltransferase (GT) activity with morphine as substrate was measured in microsomes prepared from seven human adult kidneys including one whose cortex and medulla had been separated. The formation of morphine‐3‐ and 6‐glucuronides (M3G and M6G) was determined by HPLC methods. All kidney specimen formed M3G and M6G when incubated with morphine and UDP‐glucuronic acid (UDPGA). The estimated Vmaxand Kmof morphine to form M3G and M6G were 2.2 and 0.18 nmol per mg protein and min. and 8.2 and 4.6 mM, respectively. The corresponding values for UDPGA were 1.3 and 0.13 nmol per mg protein and min. and 5.4 and 4.1 mM, respectively. The GT activity in cortex was 2.8‐fold higher than in the medulla. The human kidney thus contains glucuronyltransferase activities towards morphine, which is in contrast to previous findings

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00965.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:Changes in renal function, Na+‐K+‐ATPase activity and PAH transport system in the kidney cortex were studied in rats treated with cadmium. Subcutaneous injections of CdCl2(2 mg Cd/kg · day) for 16 days induced a marked polyuria and a hyposthenuria. These changes were accompanied by increase in urinary protein, glucose, urea, calcium, phosphate, chloride and potassium excretions. The change in urine flow was proportional to the change in total osmotic solute excretion. Creatinine excretion and TcH2O remained unchanged. Na+excretion was not increased, but the Na+‐K+‐ATPase of renal cortex was significantly inhibited. PAH uptake by renal cortical slices was markedly attenuated in Cd‐treated rats. The Vmaxfor active PAH influx was drastically reduced, but the Kmwas not changed. The passive influx and efflux of PAH across the basolateral membrane and the renal tissue oxygen consumption were not apparently altered in Cd‐treated animals. These results indicate that 1) the nature of Cd‐induced polyuria and hyposthenuria is an osmotic diuresis induced by proximal tubular rejection of various substances, and 2) the mechanism of impaired renal PAH excretion in Cd‐treated animals is a loss of organic anion carriers in proximal tubular basol

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00966.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:In a randomized cross‐over study, serum and urinary aluminum (Al) was measured in 8 patients with predialysis chronic renal failure. Samples were taken after ingestion of an Al‐containing phosphate binder (ACPB) with either water or 7% citric acid, and Al was analyzed by electrothermal atomic absorption spectrometry. Both serum levels and urinary excretion of Al increased markedly after ingestion of ACPB with citric acid. Only urinary Al excretion increased significantly after ACPB with water. Citric acid alone caused no change in serum concentration or urinary excretion of Al. The serum Al increase after ACPB with citric acid indicates that absorption of Al is taking place in both upper and lower intestines. Marked individual variations in gastrointestinal Al absorption, independent of kidney function, were seen after intake of ACPB with citric acid. These variations could not be predicted from changes in serum concentrations or from urinary excretion of Al after intake of ACPB with water. Intake of ACPB caused a significant decrease in serum phosph

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00967.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract:The tissue distribution of14C‐labeled ochratoxin A was studied in mouse using whole‐body autoradiography. The distribution was followed for 18 days after one single intravenous injection of 5 μCi/animal, corresponding to 160–230 ng toxin/g body weight. Very long persistence of14C‐ochratoxin A in the circulation was noticed and the toxin was detected in the blood even after 18 days when the experiment was finished. The radioactivity in the kidney was unequally distributed with a slightly higher concentration in the inner cortical and medullary parts. This was seen from 24 hrs and on after injection. Very high concentrations of radioactivity were found in the bile of treated animals. The radioactivity extracted from several sections was chemically characterized with thin‐layer chromatography and was found to represent14C‐

ISSN:0901-9928    

DOI:10.1111/j.1600-0773.1988.tb00968.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY