المؤلفون: van Os CH; Department of Cell Physiology, University of Nijmegen, The Netherlands., Deen PM, Dempster JA

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1994 Dec 09; Vol. 1197 (3), pp. 291-309.

نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't; Review

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Aquaporins*, Cell Membrane/*metabolism , Ion Channels/*chemistry , Water/*metabolism, Amino Acid Sequence ; Animals ; Aquaporin 1 ; Blood Group Antigens ; Cell Membrane Permeability ; Diabetes Insipidus/genetics ; Gene Expression Regulation ; Humans ; Ion Channels/genetics ; Ion Channels/metabolism ; Molecular Sequence Data ; Sequence Alignment

المؤلفون: Rose UM; Department of Cell Physiology, University of Nijmegen, The Netherlands., Hartog A, Jansen JW, Van Os CH, Bindels RJ

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1994 Jul 18; Vol. 1226 (3), pp. 291-9.

نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Calcium/*metabolism , Kidney Cortex/*metabolism , Kidney Medulla/*metabolism , Loop of Henle/*metabolism, Animals ; Calcium Channels/metabolism ; Cell Hypoxia ; Cells, Cultured ; Gallopamil/pharmacology ; Rabbits

مستخلص: The effect of anoxia on intracellular Ca2+ concentration ([Ca2+]i) in primary cultures of medullary (mTAL) and cortical (cTAL) thick ascending limb of Henle's loop was investigated. Previously, we reported a method to monitor [Ca2+]i continuously in cultured proximal tubule cells during 1 h of anoxic incubation in the absence of glycolytic substrates [1]. Complete absence of O2 was realised by inclusion of a mixture of oxygenases in an anoxic chamber. As a result of substrate-free anoxia, [Ca2+]i started to rise in individual cells of mTAL and cTAL monolayers and reached maximal levels within 60 min after starting the anoxic incubation. Anoxia induced significant increases in [Ca2+]i from 76 +/- 1 (n = 176) to 469 +/- 18 nM (n = 203) in mTAL monolayers and from 58 +/- 1 (n = 91) to 442 +/- 27 nM (n = 106) in cTAL monolayers (P < 0.05). At the re-introduction of oxygen and glucose, elevated [Ca2+]i rapidly declined to 110 +/- 4 (n = 167) and 105 +/- 5 nM (n = 87) in mTAL and cTAL, respectively (P < 0.05). Removal of extracellular Ca2+ and addition of 0.1 mM La3+ partially prevented anoxia-induced increases in [Ca2+]i in both cell types. The L-type Ca2+ channel blocker D600 (1 microM) was as effective as Ca2+ removal and La3+ addition. Comparing mTAL and cTAL cells, only one difference was consistently observed. Prevention of Ca2+ influx by exposure to La3+ combined with Ca2+ removal or addition of 1 microM D600 had a greater inhibitory effect on anoxic [Ca2+]i values in mTAL than in cTAL monolayers, indicative of a larger role of Ca2+ influx through L-type Ca2+ channels in anoxia-induced increases in [Ca2+]i in the former cell type. In conclusion, substrate-free anoxia reversibly increases [Ca2+]i in primary cultures of cTAL and mTAL, which results from Ca2+ release from stores as well as from Ca2+ influx via D600-sensitive Ca2+ channels.

المؤلفون: Timmermans JA; Department of Physiology, University of Nijmegen, The Netherlands., Kaune R, Bindels RJ, van Os CH

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1991 Jun 18; Vol. 1065 (2), pp. 177-84.

نوع المنشور: Journal Article

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Calcitriol/*deficiency , Calcium-Transporting ATPases/*metabolism , Duodenum/*enzymology, Adenosine Triphosphate/pharmacology ; Animals ; Biological Transport, Active/drug effects ; Blotting, Western ; Calcium/metabolism ; Calcium Channels/metabolism ; Calcium-Transporting ATPases/analysis ; Calmodulin/metabolism ; Cell Membrane/enzymology ; Enzyme-Linked Immunosorbent Assay ; Kinetics ; Rickets/enzymology ; Swine

مستخلص: Previous studies have identified a calmodulin-stimulated ATP-dependent Ca2+ pump as the major Ca2+ efflux pathway in enterocytes. Here, we developed methods to quantify the number of Ca2+ pumps in basolateral and intracellular membranes from porcine duodenum. By the use of a pig strain with a genetic defect in renal 1 alpha-hydroxylase, we were able to investigate the influence of 1,25(OH)2D3-deficiency on the number of Ca(2+)-ATPases in porcine duodenum. The amount of Ca(2+)-ATPase in isolated basolateral membranes was 5.5 +/- 0.7 micrograms/mg protein, while the Vmax of ATP-dependent Ca2+ transport into inside-out resealed basolateral membrane vesicles was 2.6 +/- 0.4 nmol/mg protein per min. From these data we estimated roughly about 95 x 10(3) plasma membrane Ca2+ pump sites per enterocyte. In addition, the amount of intracellular Ca(2+)-ATPase in microsomal fractions was 0.41 +/- 0.02 microgram/mg protein. Comparison of these parameters between control and rachitic animals showed that Ca2+ pump capacities in both basolateral membranes and microsomal fractions of porcine duodenum are not influenced by 1,25(OH)2D3-deficiency. In conclusion, stimulatory effects of 1,25(OH)2D3 on intestinal Ca2+ transport most likely result from specific effects on apical influx and facilitation of cytosolic Ca2+ diffusion by Ca(2+)-binding proteins and not from an increase in Ca2+ pumping capacity in basolateral membranes.

المؤلفون: van Hoek AN; Department of Physiology, University of Nijmegen, The Netherlands., de Jong MD, van Os CH

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1990 Dec 14; Vol. 1030 (2), pp. 203-10.

نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: 4-Chloromercuribenzenesulfonate/*pharmacology , Dimethyl Sulfoxide/*pharmacology , Mannitol/*metabolism , Mercury/*pharmacology , Microvilli/*metabolism , Sulfhydryl Reagents/*pharmacology , Urea/*metabolism , Water/*metabolism, Animals ; Cell Membrane Permeability ; Cysteine/pharmacology ; Dithiothreitol/pharmacology ; Kidney/drug effects ; Kidney/metabolism ; Kidney/ultrastructure ; Kinetics ; Microvilli/drug effects ; Osmosis ; Rats ; Sodium Chloride/metabolism

مستخلص: The effects of dimethylsulfoxide, DMSO, and mercurial sulfhydryl reagents have been studied on water and small solute permeability of rat renal brush border membrane vesicles. Water and solute permeability was measured by mixing membrane vesicles with hypertonic solutions in a stopped-flow apparatus and following osmotically-induced changes in vesicular volume via changes in scattered light intensity. The rate constant of the fast osmotic shrinkage is proportional to the osmotic water permeability, while the rate constant of the slow reswelling phase is proportional to the solute permeability. Using mannitol as the osmotic agent, the osmotic shrinkage of rat renal brush border membrane vesicles followed a biphasic time course. 80% of the vesicles shrunk with a rate constant of approx. 50 s-1 and 20% with a rate constant of approx. 2 s-1. DMSO decreased dose-dependently the amplitude of the fast osmotic shrinkage, without affecting its rate constant. In contrast to DMSO, HgCl2 decreased the rate constant but not the amplitude of the fast osmotic shrinkage of renal brush border vesicles. Between 40-50 microM HgCl2, the inhibition of the fast osmotic shrinkage was completed. DMSO and HgCl2 increase the activation energy of water permeation in renal membranes from 3 to 12-15 kcal/mol. DMSO and HgCl2 did not affect the rate constant of the slow osmotic shrinkage of renal membrane vesicles and were also without effect on osmotic shrinkage of small intestinal brush border and pure phospholipid vesicles. In renal brush border membranes, HgCl2 at low concentrations (less than 10 microM) increased by 15-fold the permeability to NaCl and urea but not to mannitol, an effect which precedes the inhibition of water permeability at higher HgCl2 concentrations. The increase in small solute permeability was irreversible while the inhibition of water permeability could be reversed with cysteine and dithiothreitol. We conclude that water and small solute pathways in rat renal brush border membranes are completely separate entities, which are effected differently by DMSO and HgCl2. These pathways for water and solutes must be membrane proteins since neither DMSO nor HgCl2 affect the permeability properties of pure phospholipid vesicles.

المؤلفون: van Os CP, Vente M, Vliegenthart JF

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1979 Jul 27; Vol. 574 (1), pp. 103-11.

نوع المنشور: Journal Article

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Lipid Peroxides/*analysis , Lipoxygenase/*metabolism , Magnetic Resonance Spectroscopy/*methods, Borohydrides ; Linoleic Acids ; Stereoisomerism

مستخلص: A method is presented for determination of the enantiomeric composition of hydroxyperoxides formed by enzymic oxygenation of unsaturated fatty acids. After reduction of the hydroperoxy group with NaBH4, and esterification, the positional isomers of the resulting hydroxy compounds are separated by high performance liquid chromatography. The latter are subsequently subjected to a chiral derivatization to form diastereomeric alpha-methoxy-alpha-trifluoromethylphenylacetate esters. Determination of the diastereomeric composition by a NMR shift experiment furnishes the enantiomeric composition of the parent hydroperoxides. The method has been applied to the hydroperoxides formed by incubation of linoleic acid by corn germ or soybean lipoxygenase. Our results indicate that under the conditions used the hydroperoxides are mainly enantiospecifically formed.

المؤلفون: van Corven EJ, Roche C, van Os CH

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1985 Nov 07; Vol. 820 (2), pp. 274-82.

نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Calcium/*metabolism , Calcium-Binding Proteins/*metabolism , Calcium-Transporting ATPases/*metabolism , Calmodulin/*metabolism , Duodenum/*metabolism, Alkaline Phosphatase/metabolism ; Animals ; Biological Transport, Active ; Cytoplasm/metabolism ; Male ; Mannitol/metabolism ; Rats ; Sodium/metabolism ; Sodium-Potassium-Exchanging ATPase/metabolism ; Succinate Dehydrogenase/metabolism ; Sucrase/metabolism ; Thiamine Pyrophosphatase/metabolism

مستخلص: The migration of intestinal epithelial cells from the crypts to the tips of villi is associated with progressive cell differentiation. The changes in Ca2+-ATPase activity and ATP-dependent Ca2+-transport rates in basolateral membranes from rat duodenum were measured during migration along the crypt-villus axis. In addition, vitamin D-dependent calcium-binding protein and calmodulin content were measured in homogenates of six cell populations which were sequentially derived from villus tip to crypt base. Alkaline phosphatase activity was highest at the tip of the villus (fraction I) and decreased more than 20-fold towards the crypt base (fraction VI). (Na+ + K+)-ATPase activity also decreased along the villus-crypt axis but in a less pronounced manner than alkaline phosphatase. ATP-dependent Ca2+-transport in basolateral membranes was highest in fraction II (8.2 +/- 0.3 nmol Ca2+/min per mg protein) and decreased slightly towards the villus tip and base (fraction V). The youngest cells in the crypt had the lowest Ca2+-transport activity (0.9 +/- 0.1 nmol Ca2+/min per mg protein). The distribution of high-affinity Ca2+-ATPase activity in basolateral membranes correlated with the distribution of ATP-dependent Ca2+-transport. The activity of Na+/Ca2+ exchange was equal in villus and crypt basolateral membranes. Compared to the ATP-dependent Ca2+-transport system, the Na+/Ca2+ exchanger is of minor importance in villus cells but may play a more significant role in crypt cells. Calcium-binding protein decreased from mid-villus towards the villus base and was undetectable in crypt cells. Calmodulin levels were equal along the villus-crypt axis. It is concluded that vitamin D-dependent calcium absorption takes primarily place in villus cells of rat duodenum.

المؤلفون: Bindels RJ, van den Broek LA, van Os CH

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1987 Feb 12; Vol. 897 (1), pp. 83-92.

نوع المنشور: Journal Article

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Kidney Tubules, Proximal/*metabolism , Microvilli/*metabolism , Phosphates/*metabolism , Sodium/*pharmacology, Animals ; Biological Transport, Active/drug effects ; Edetic Acid/pharmacology ; Glycerophosphates/pharmacology ; Hydrogen-Ion Concentration ; Kinetics ; Male ; Rats ; Rats, Inbred WKY ; Temperature

مستخلص: The kinetics of Na+-dependent phosphate uptake in rat renal brush-border membrane vesicles were studied under zero-trans conditions at 37 degrees C and the effect of pH on the kinetic parameters was determined. When the pH was lowered it turned out to be increasingly difficult to estimate initial rates of phosphate uptake due to an increase in aspecific binding of phosphate to the brush border membrane. When EDTA or beta-glycerophosphate was added to the uptake medium this aspecific binding was markedly reduced. At pH 6.8, initial rates of phosphate uptake were measured between 0.01 and 3.0 mM phosphate in the presence of 100 mM Na+. Kinetic analysis resulted in a non-linear Eadie-Hofstee plot, compatible with two modes of transport: one major low-affinity system (Km approximately equal to 1.3 mM), high-capacity system (Vmax approximately equal to 1.1 nmol/s per mg protein) and one minor high-affinity (Km approximately equal to 0.03 mM), low-capacity system (Vmax approximately equal to 0.04 nmol/s per mg protein). Na+-dependent phosphate uptake studied far from initial rate conditions i.e. at 15 s, frequently observed in the literature, led to a dramatic decrease in the Vmax of the low-affinity system. When both the extra- and intravesicular pH were increased from 6.2 to 8.5, the Km value of the low-affinity system increased, but when divalent phosphate is considered to be the sole substrate for the low-affinity system then the Km value is no longer pH dependent. In contrast, the Km value of the high-affinity system was not influenced by pH but the Vmax decreased dramatically when the pH is lowered from 8.5 to 6.2. These results suggest that the low-affinity, high-capacity system transports divalent divalent phosphate only while the high-affinity, low-capacity system may transport univalent as well as divalent phosphate. Raising medium sodium concentration from 100 to 250 mM increased Na+-dependent phosphate uptake significantly but the pH dependence of the phosphate transport was not influenced. This observation makes it rather unlikely that pH changes only affect the Na+ site of the Na+-dependent phosphate transport system.

المؤلفون: van Os CP, Rijke-Schilder GP, Vliegenthart JF

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1979 Dec 18; Vol. 575 (3), pp. 479-84.

نوع المنشور: Journal Article

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Linoleic Acids/*metabolism , Lipid Peroxides/*biosynthesis , Lipoxygenase/*metabolism , Plants/*enzymology, Circular Dichroism ; Fabaceae/enzymology ; Kinetics ; Linoleic Acids/isolation & purification ; Plants, Medicinal ; Glycine max

مستخلص: Type-2 lipoxygenases from soybeans and peas, which have a pH optimum of 6--7 were examined for oxygenation activity at pH 9.0. The reaction velocity was found to be strongly dependent on substrate concentration. At higher substrate concentrations an inhibitory effect was observed, which is connected with the occurrence of a kinetic lag phase. On incubation of linoleic acid at pH 9.0 with either of these enzymes predominantly 9-LR-hydroperoxy-10-trans,12-cis-octadecadienoic acid is formed. The similarity of the product specificity with that of prostaglandin synthetase is discussed in view of the formation of prostaglandin-like substances by soybean lipoxygenase-2 (Bild, G.S., Bhat, S.G., Ramadoss, C.S. and Axelrod, B. (1978) J. Biol. Chem, 253, 21--23).

المؤلفون: Van Os CP, Rijke-Schilder GP, Van Halbeek H, Verhagen J, Vliegenthart JF

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1981 Jan 26; Vol. 663 (1), pp. 177-93.

نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Arachidonic Acids*/chemical synthesis, Lipoxygenase/*metabolism , Plants/*enzymology, Arachidonate Lipoxygenases ; Kinetics ; Magnetic Resonance Spectroscopy ; Mass Spectrometry ; Methods ; Glycine max ; Spectrophotometry, Ultraviolet ; Substrate Specificity

مستخلص: The kinetic parameters of the first and second oxygenation of arachidonic acid by soybean lipoxygenase-1 were determined and found to be for the first step at pH 10.0, Km (arachidonic acid) = 8.5 +/- 0.5 microM; kcat = 225 +/- 7 s-1 and for the second step at pH 8.7 Km (15-HPETE) = 440 +/- microM; kcat = 25 +/- 1 s-1. In the second oxygenation for which 15-Ls-hydroperoxy 5-cis, 8-cis, 11-cis 13-trans-eicosatetraenoic acid is a substrate, two isomeric dihydroperoxy fatty acids are formed. After separation of the corresponding dihydroxy esters by high-performance liquid chromatography, they were identified by mass-spectrometry, 1H- and 13C-NMR spectroscopy as 8-DS, 15-LS-dihydroperoxy 5-cis, 9-trans, 11-cis, 13-trans-eicosatetraenoic acid and 5-DS, 15-LS-dihydroperoxy 6-trans, 8-cis, 11-cis, 13-trans-eicosatetraenoic acid. Independent evidence for the absolute configurations was obtained by capillary gas-liquid chromatography of diastereomeric R-(-)-2-butyl esters of the acetylated 2-hydroxy carboxylic acids produced by oxidative ozonolysis of the acetylated dihydroxy fatty acids. It is concluded that soybean lipoxygenase-1 produces hydroperoxides with predominantly the S-configuration irrespective of the position in the fatty acid which is oxygenated.

المؤلفون: Os CH, Michels JA, Slegers JF

المصدر: Biochimica et biophysica acta [Biochim Biophys Acta] 1976 Sep 07; Vol. 443 (3), pp. 545-55.

نوع المنشور: Journal Article

بيانات الدورية: Publisher: Elsevier Pub. Co Country of Publication: Netherlands NLM ID: 0217513 Publication Model: Print Cited Medium: Print ISSN: 0006-3002 (Print) Linking ISSN: 00063002 NLM ISO Abbreviation: Biochim Biophys Acta Subsets: MEDLINE

مواضيع طبية MeSH: Body Water/*metabolism , Gallbladder/*metabolism, Animals ; Biological Transport, Active ; Electric Stimulation ; Epithelium/drug effects ; Epithelium/metabolism ; Gallbladder/drug effects ; In Vitro Techniques ; Methods ; Rabbits ; Thiocyanates/pharmacology

مستخلص: A volumetric method has been developed which permits continuous registration of volume flows across epithelial tissues. The method was applied to volume flow measurements across rabbit gall bladder epithelium. The rate of fluid reabsorption measured in this way was twice as high as previously observed in sac preparations of the gall bladder. This is probably due to better aeration and stirring of the mucosal solution. It was demonstrated that electrical gradients across the gall bladder induced volume flows towards the negative electrode. In non-transporting bladders volume flows were linearly related with current between 300 and 900 muA in both directions. However, volume flow rates were three times higher from mucosa to serosa than in the opposite direction. From the magnitude of polarization potentials, observed after switching off the current, the conclusion was reached that all of the current-induced volume flow is an osmotic flow due to salt polarization in the unstirred layers of the tissue. By implication, so-called streaming potentials observed during osmotic flows reflect solely polarization effects. In actively transporting gall bladders a 200 muA current increased or decreased the flow rate twice as much as expected from polarization effects alone. Therefore passage of current interfered directly with the active transport mechanism of gall bladder epithelium.