摘要:

AbstractThe study of the control of aldosterone synthesis and secretion by the rat adrenal gland has over the past thirty years involved the application of many differentin vivoandin vitrotechniques. In this review the relationship between the data that each of these methods has produced is compared. There are striking differences in overall steroid production rates, and in the qualitative nature of the steroid profile which the various methods produce. In particular, aldosterone is secreted at higher ratesin vivo, and when whole tissue preparations are usedin vitro, than in incubations of isolated glomerulosa cells. In addition, while corticosterone is a major product of glomerulosa tissuein vitro, the available evidence suggests that it is not a major glomerulosa productin vivo.

ISSN:0263-6484    

DOI:10.1002/cbf.290030402

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractA modified cytochemical assay for [Na‐K]ATPase in cryostat sections of kidney was further characterized and used to quantify activity in seven functionally distinct sites along the rat nephron. The activity of [Na‐K]ATPase was defined as the difference in ATPase activity in specifically identified tubules contained in serial sections incubated with and without ouabain. Preincubation of sections with ouabain was required for maximal inhibition of [Na‐K]ATPase activity in several distal sites. The concentration of oubain necessary for maximal inhibition of activity was 3·0 mMand half‐maximal inhibition was obtained in all regions with 30–100μMouabain. In distal sites, [Na‐K]ATPase formed a higher proportion of total ATPase activity (60–80 per cent) than in proximal sites(20–40 per cent). Enzyme activity was quantified using two different methods. The first measured activity over the basal region of tubules and gave an index of the concentration of [Na‐K]ATPase over the basal lateral infoldings of cells composing the tubule. The second read activity over the entire cross section of tubules and provided an estimate of [Na‐K]ATPase per length of tubule. The highest activities over the basal region were obtained from tubules of the distal nephron including the inner (MALin) and outer (MALout) medullary ascending limb, distal convoluted tubule (DCT) and connecting segment (CS). Lower activities were obtained in proximal convoluted (PCT) tubules, proximal straight (PS) tubules and the papillary collecting duct (PD). Distal convoluted tubules contained the highest activity per length of tubule. Other sites contained lower levels of activity in the following order: MALin>MALout>PCT>PD>PS. The modifications introduced increase the sensitivity and precision of this assay and permit the application of this technique to studies of [Na‐K]ATPase activity in the major functional reg

ISSN:0263-6484    

DOI:10.1002/cbf.290030403

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractEffect of tricyclohexylhydroxytin (plictran) on Ca2+‐ATPase activity was studied in rat brain synaptosomes underin vitroandin vivoconditions. Plictran inhibited basal Ca2+‐ATPase activity with an IC50value of 6 nMsuggesting its interaction with calcium transport phenomenon. Plictran inhibited calmodulin (CaM) activated Ca2+‐ATPase in a concentration‐dependent manner. A complete reversal of calmodulin activation of Ca2+‐ATPase was observed with 2–3 nMplictran. A 50 per cent decrease of CaM activated Ca2+‐ATPase was observed with 0·5 nMplictran, a concentration at which no significant effect was observed on basel enzyme activity. Of all the brain fractions studied, calmodulin levels in P2fractions alone were reduced significantly to about 75 per cent of control values in plictran treated rats. The synaptosomal Ca2+‐ATPase was also decreased by 35 per cent, 42 per cent and 65 per cent in 10, 20 and 40 mg plictran kg−1day−1treated rats for 3 days respectively. The activity levels of Ca2+‐ATPase in 10 and 20 mg plictran kg−1day−1treated rats were restored to normal level by exogenously added calmodulin. These results suggest that plictran may disrupt synaptic function by altering calcium and calmodulin regulated processes in

ISSN:0263-6484    

DOI:10.1002/cbf.290030404

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractSpecific and high affinity binding sites for angiotensin II were demonstrated in the membranes of the developing rat metanephros during the second half of pregnancy and in the newborn by binding studies with125I angiotensin II. Only one type of angiotesin receptor was found during intrauterine life while after birth two classes of angiotensin receptors were present in the membranes of the cortical renal tissue.

ISSN:0263-6484    

DOI:10.1002/cbf.290030405

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractIt has been shown that serine proteses are involved in aldosterone and 18‐hydroxycorticosterone production by the rat adrenal zona glomerulosa in response to a variety of stimulants. From evidence presented for various tissues, including the rat adrenal cortex, the observation that adenylate cyclase can be activated by proteolytic enzymes and inhibited by protease inhibitors has led to the suggestion that serine proteases may also be involved in the hormonal stimulation of adenylate cyclase. In studies designed to test this hypothesis using protease inhibitors, only high concentrations (>10−4M) of TAME (p‐tosyl‐L‐arginine methyl ester) inhibited ACTH stimulated steroid and cAMP production in rat adrenal glomerulosa cells. TPCK (tosyl‐L‐phenylalanine high concentrations) and TLCK (tosyl‐L‐lysine chloromethylketone) were found to have a similar effect at very high concentrations (10−2M) but had no effect at the serine protease inhibitory concentration of 5 × 10−6M. Other protease inhibitors tested had no effect on ACTH‐stimulated cAMP but the inhibitory effect of high concentrations of protease inhibitors on ACTH‐stimulated adenylate cyclase was duplicated by the polyanion dextran sulphate. The results suggest that the inhibitors act through non‐specific membrane effects and that proteases are not involved in the activation of zona glomerulosa adenylate cyclase by ACTH. In view of these findings it is concluded that a more rigorous approach should be applied to the use of protease inhibitors in whole cell systems, and that the concept of hormonal activation of adenylate cyclase via proteolytic events, which is based on studies with such inhibi

ISSN:0263-6484    

DOI:10.1002/cbf.290030406

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractRat liver mitochondria were stored at 0–4°C for several days using an appropriate medium and energy source. The elimination of the majority of microsomes and lysosomes, that normally contaminate isolated mitochondria, had a positive effect in preservation of respiratory control, P:O ratio, and monoamine oxidase activity during long term stora

ISSN:0263-6484    

DOI:10.1002/cbf.290030407

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe biliary GSSG efflux rate of normoxic perfused rat liver was 1·5 ± 0·2 nmol/min/g liver wet weight. The GSSG efflux rate as indicator for the flux through the glutathine peroxidase and, therefore, for an oxidative loading incvreased with the extent of hypoxia. 2·6 ± 0·5 nmol/min/g were released from the severely hypoxic liver. The hydroxyl radical scavenger formate as well as the xanthine oxidase inhibitor allopurinol reduced the efflux rate of GSSG.GSH was released from the perfused liver at a rate of 15·5 nmol/min/g which was nearly unchanged in severe hypoxia.The high rate of glucose liberation from the hypoxic liver declined to almost that of the normoxic organ in the presence of formate.There is an ‘oxidative stress’ during hypoxic liver perfusion which probably originates from increased generation of activated oxygen species in the degradation of purine n

ISSN:0263-6484    

DOI:10.1002/cbf.290030408

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe sensitivity of polymorphonuclear leukocytes (PMN) toN‐formyl‐methionyl‐leucyl‐phenylalanine (fMet‐Leu‐Phe) for chemotaxis and for lysosomal enzyme release was examined using the PMN of four primate species, human (H. sapiens), chipanzee (P. troglodytes), rhesus monkey (M. mulatta), and cotton‐heded tamarin (S. (O) oedipus). The 50 per cent effective concentration (EC50) of fMet‐Leu‐Phe for chemoxaxis were 2·5 × 10−9Min human, 10−9Min chimpanzee, 8 × 10−8Min rhesus moneky, and 3·3 × 10−6Min tamarin. The EC50values of fMet‐Leu‐Phe for myeloperoxides (MPO) release were 10−8Min human, 4 × 10−8Min chimpanzee, 4 × 10−8Min rhesus monkey, and 10−6Min tamarin and those for β‐glucuronidase release were 4 × 10−9M, 6·4 × 10−8M, 1·8 × 10−7M, and 1·6 × 10−6M, respectively. Thus, the sensitivity of fMet‐Leu‐Phe for chemotaxis was in the order: chimpanzee ≃ human>rhesus monkey>tamarin, and that for the release of lysosomal enzymes, MPO and β‐glucuronidase, was in the order: human>chimpanzee>rhesus monkey>tamarin.These results appear to indicate that the sensitivity to fMet‐Leu‐Phe increases in the order of evolution of primates towards the human, and suggest that the sensitivity to fMet‐Leu‐Phe increases in the order of evolution of primates towards the human, and suggest that the sensitivity of

ISSN:0263-6484    

DOI:10.1002/cbf.290030409

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY

ISSN:0263-6484    

DOI:10.1002/cbf.290030401

出版商:John Wiley&Sons, Ltd.    

年代:1985

数据来源: WILEY