scholarly journals Inhibitory effect of colchicines on amylase secretion by rat parotid glands: possible localization in the golgi area

1977 ◽  
Vol 73 (3) ◽  
pp. 578-593 ◽  
Author(s):  
C Patzelt ◽  
D Brown ◽  
B Jeanrenaud
Keyword(s):  
De Novo ◽  
Secretory Granules ◽  
Inhibitory Effect ◽  
Binding Activity ◽  
Amylase Secretion ◽  
Parotid Glands ◽  
Secretory Material ◽  
Delayed Effect ◽  
Rat Parotid

Colchicine inhibited amylase secretion by isolated rat parotid glands only 6 h after administration of the drug in vivo. This delayed effect was not the result of the inability of the drug to reach its reaction site. When parotid glands were emptied of their secretory granules by isoproterenol treatment, the subsequent replenishment of cells with granules was inhibited by colchicines. Colchicine concomitantly produced alterations of the Golgi complexes, the cisternae of which were reduced in size and surrounded by clusters of microvesicles. Incubation of parotid glands with colchicines for prolonged durations failed to alter stored amylase secretion as stimulated by isoproterenol, but it inhibited the release of de novo synthesized enzyme. Another colchicines-binding activity, firmly bound to the particular fraction of homogenates, was found, of which a part may represent membrane located microtubular protein. An assembly-disassembly cycle of microtubules appears to exist in the parotid gland, as in the liver. However, only 14 percent of tubulin was found to be polymerized as microtubules in parotid glands as opposed to 40 percent in the liver. The present data suggest that colchicine primarily inhibits the transfer of secretory material towards or away from the Golgi complexes but not the hormone-stimulated secretion of stored amylase.

Intracellular Elemental Concentrations in Resting and Secreting Rat Parotid Glands

1987 ◽  
Vol 66 (2) ◽  
pp. 537-540 ◽  
Author(s):  
K.T. Izutsu ◽  
D.E. Johnson ◽  
M. Goddard
Keyword(s):  
Secretory Granules ◽  
Dry Weight ◽  
Parotid Glands ◽  
X Ray ◽  
Elemental Concentrations ◽  
Saliva Secretion ◽  
Concentration Changes ◽  
Rat Parotid ◽  
Micro Analysis

Electron probe x-ray micro-analysis was used to study the elemental concentration changes that occur during pilocarpine-stimulated saliva secretion. Quantitative x-ray micro-analysis of elemental concentrations in intracellular compartments of rat parotid glands stimulated in vivo with pilocarpine showed that Na concentration was significantly increased, while K concentration was significantly reduced. The magnitude of these changes was consistent with values obtained in other tissues with the x-ray micro-analysis method, and in the same tissue with other experimental methods. Comparisons with results from studies utilizing dispersed acini suggest that acinar dispersion procedures may affect intracellular elemental concentrations. Total electrolyte concentrations in cytoplasm and secretory granules were estimated to increase on a dry-weight basis following pilocarpine stimulation. The former change is consistent with the notion of a trans-cellular route of salivary fluid flow, while the latter change may be important in the exocytosis of secretory granules.

scholarly journals CONCOMITANT SYNTHESIS OF MEMBRANE PROTEIN AND EXPORTABLE PROTEIN OF THE SECRETORY GRANULE IN RAT PAROTID GLAND

1971 ◽  
Vol 50 (1) ◽  
pp. 187-200 ◽  
Author(s):  
Abraham Amsterdam ◽  
Michael Schramm ◽  
Itzhak Ohad ◽  
Yoram Salomon ◽  
Zvi Selinger
Keyword(s):  
Amino Acids ◽  
Secretory Granule ◽  
De Novo ◽  
Secretory Granules ◽  
Specific Radioactivity ◽  
Staining Intensity ◽  
Granule Membrane ◽  
Rat Parotid ◽  
Cell Fractions

After enzyme secretion the membrane of the secretory granule, which had been fused to the cell membrane, was resorbed into the cell. Experiments were therefore carried out to test whether formation of new secretory granules involves reutilization of the resorbed membrane or synthesis of a new membrane, de novo, from amino acids. Incorporation of amino acids-14C into proteins of various cell fractions was measured in vivo, 30, 120, and. 300 min after labeling. At all times the specific radioactivity of the secretory granule membrane was about equal to that of the granule's exportable content. At 120 and 300 min the specific radioactivity of the granule membrane and of the granule content was much higher than that of any other subcellular fraction. It is therefore concluded that the protein of the membrane is synthesized de novo concomitantly with the exportable protein. The proteins of the granule membrane could be distinguished from those of the granule content by gel electrophoresis. All major bands were labeled proportionately to their staining intensity. The amino acid composition of the secretory granule membrane was markedly different from that of the granule's content and also from that of the mitochondrial membrane. The granule membrane showed a high proline content, 30 moles/100 moles amino acids. The analyses show that the radioactivity of the granule membrane is indeed inherent in its proteins and is not due to contamination by other fractions. The possibility is considered that the exportable protein leaves the endoplasmic reticulum already enveloped by the newly synthesized membrane.

Mechanism of the inhibitory effect of trifluoperazine on isoprenaline-evoked amylase secretion from isolated rat parotid glands

1986 ◽  
Vol 35 (23) ◽  
pp. 4121-4124 ◽  
Author(s):  
Stephen Arkle ◽  
Philip D. Pickford ◽  
Paul S. Schofield ◽  
Christopher Ward ◽  
Barry E. Argent
Keyword(s):  
Inhibitory Effect ◽  
Amylase Secretion ◽  
Parotid Glands ◽  
Rat Parotid ◽  
Isolated Rat

Chloride transport across the membrane of parotid secretory granules

1990 ◽  
Vol 259 (3) ◽  
pp. C413-C420 ◽  
Author(s):  
K. W. Gasser ◽  
U. Hopfer
Keyword(s):  
Chloride Transport ◽  
Secretory Granules ◽  
Disulfonic Acid ◽  
Parotid Glands ◽  
Transport Pathways ◽  
Anion Selectivity ◽  
Granule Membrane ◽  
Cytoplasmic Side ◽  
Cl Conductance

The Cl- transport pathways in secretory granules isolated from the parotid glands of rats were characterized by the technique of ionophore-induced lysis in defined salt solutions. The granules were shown to possess a Cl- conductance that exhibited a distinct anion selectivity with a sequence I- greater than Br- greater than Cl- greater than F- greater than SO4(2-) much greater than gluconate-. This conductance could be reduced approximately 40% by the stilbene 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) from the cytoplasmic side; the half-maximal concentration for inhibition was 50 microM. Furthermore, the apparent Cl- conductance was reduced by outwardly directed granule H+ gradients and stimulated by inwardly directed gradients. An outwardly directed H+ gradient mimics the in vivo environment and may serve in a regulatory capacity, providing for a tonic inhibition of transport until the granule fuses with the luminal membrane. The granules also possessed a Cl(-)-HCO3- exchange based on electroneutrality of Cl- uptake and stimulation of this uptake by HCO3-. This pathway displayed a different anion selectivity, I- greater than Br- greater than F- greater than Cl- much greater than SO4(2-) much greater than gluconate-, and was not inhibited by SITS on the cytoplasmic side. The presence of these electrolyte transport pathways in the granule membrane is consistent with the production of primary fluid by parotid acinar cells after fusion of granules with the luminal plasma membrane.

scholarly journals Mechanisms underlying SNI-2011-induced amylase secretion from rat parotid glands

2000 ◽  
Vol 82 ◽  
pp. 221
Author(s):  
Mariusz T. Skowronsld ◽  
Yasuko Ishikawa ◽  
Hajime Ishida
Keyword(s):  
Amylase Secretion ◽  
Parotid Glands ◽  
Rat Parotid

Sialylation of the Sialic Acid Binding Lectin Sialoadhesin Regulates Its Ability to Mediate Cell Adhesion

Blood ◽  
1999 ◽  
Vol 93 (4) ◽  
pp. 1245-1252 ◽  
Author(s):  
Yvonne C. Barnes ◽  
Tim P. Skelton ◽  
Ivan Stamenkovic ◽  
Dennis C. Sgroi
Keyword(s):  
Sialic Acid ◽  
Inhibitory Effect ◽  
Binding Activity ◽  
Cell Surface Receptor ◽  
Common Mechanism ◽  
Specific Cell ◽  
Sialic Acid Binding ◽  
Surface Receptor ◽  
Mediate Cell

The macrophage-specific cell surface receptor sialoadhesin, which is a member of the newly recognized family of sialic acid binding lectins called siglecs, binds glycoprotein and glycolipid ligands containing a2-3–linked sialic acid on the surface of several leukocyte subsets. Recently, the sialic acid binding activity of the siglec CD22 has been demonstrated to be regulated by sialylation of the CD22 receptor molecule. In the present work, we show that desialylation of in vivo macrophage sialylconjugates enhances sialoadhesin-mediated lectin activity. Herein, we show that receptor sialylation of soluble sialoadhesin inhibits its binding to Jurkat cell ligands, and that charge-dependent repulsion alone cannot explain this inhibition. Furthermore, we show that the inhibitory effect of sialic acid is partially dependent on the presence of an intact exocyclic side chain. These results, in conjunction with previous findings, suggest that sialylation of siglecs by specific glycosyltransferases may be a common mechanism by which siglec-mediated adhesion is regulated.

scholarly journals Morphometric Measurements to Quantify the Cerulein Induced Hyperstimulatory Pancreatitis of Rats under the Protective Effect of Lectins

1998 ◽  
Vol 17 (4) ◽  
pp. 219-230 ◽  
Author(s):  
Ludwig Jonas ◽  
Ulrike Mikkat ◽  
Anke Witte ◽  
Uta Beckmann ◽  
Katrin Dölker ◽  
...  
Keyword(s):  
Protective Effect ◽  
Amylase Activity ◽  
Acinar Cells ◽  
Inhibitory Effect ◽  
Pancreatic Acinar Cells ◽  
Amylase Secretion ◽  
Ulex Europaeus ◽  
Serum Amylase Activity

In preceding papers we demonstrated an inhibitory effect of wheat germ agglutinin (WGA) and Ulex europaeus agglutinin (UEA) on the cholecystokinin (CCK) binding to the CCK receptor of rat pancreatic cells and also on the CCK induced Ca2+release and α-amylase secretionin vitroas well as on pancreatic secretion of intact ratsin vivo. In the present study we show the same inhibitory effect of both lectins on the cerulein pancreatitis of rats. This acute pancreatitis was induced by supramaximal injections (5 µg/kg/h iv or 10 µg/kg/h ip) of the CCK analogue cerulein in rats every hour. To monitor the degree of pancreatitis, we measured the number and diameter of injury vacuoles in the pancreatic acinar cells as one of the most important signs of this type of pancreatitis by light microscopic morphometry with two different systems on paraffin sections. Furthermore, the serum α-amylase activity was measured biochemically. We found a correlation between the diameter of vacuoles inside the acinar cells and the serum enzyme activity up to 24 h. The simultaneous ip administration of cerulein and WGA or UEA in a dosage of 125 µg/kg/h for 8 h led to a reduction of vacuolar diameter from 13.1 ± 2.0 µm (cerulein) to 7.5 ± 1.1 µm (cerulein + WGA) or 7.2 ± 1.3 µm (cerulein + UEA). The serum amylase activity was reduced from 63.7 ± 15.8 mmol/l \times min (cerulein) to 37.7 ± 11.8 (cerulein + WGA) or 39.4; +52.9; -31.1 (cerulein + UEA-I). Both parameters allow the grading this special type of pancreatitis to demonstrate the protective effect of the lectins.

scholarly journals Ribonuclease-Gold Labels Heparin in Human Mast Cell Granules: New Use for an Ultrastructural Enzyme Affinity Technique

1998 ◽  
Vol 46 (6) ◽  
pp. 695-706 ◽  
Author(s):  
Ann M. Dvorak ◽  
Ellen S. Morgan
Keyword(s):  
Mast Cell ◽  
Cell Biology ◽  
Enzyme Inhibitors ◽  
De Novo ◽  
Secretory Granules ◽  
Human Mast Cell ◽  
Electron Microscopic ◽  
Binding Characteristics ◽  
Cord Blood Cell

We evaluated an enzyme affinity-gold ultrastructural technique designed to identify RNA-rich structures, based on an RNase-gold (R-G) probe in human mast cells (HMCs). As expected, the R-G technique labeled RNA-containing ribosomes and nucleoli in HMCs. The heparin-rich secretory granules in HMCs were also labeled. Extensive studies revealed that HMCs isolated from lung or skin and sustained in short-term cultures, derived de novo in growth factor-supplemented cord blood cell cultures, or present in vivo in multiple sites all shared this property. We performed a large number of controls designed to examine the HMC granule binding characteristics of gold alone, of irrelevant protein- or enzyme-gold reagents, of the role of charge and enzyme activity after various enzyme digestions, after blocking with macromolecules, after exposure to inhibitors of RNase, of heparin, or to irrelevant enzyme inhibitors, including staining of macromolecule-containing test agar blocks and a variety of combined absorption and digestion experiments of the binding of R-G to HMC granules. These studies established that the R-G method detected heparin in this site in conventionally prepared, well-preserved electron microscopic samples. These findings demonstrate a new use for this enzyme affinity-gold technique in mast cell biology, based on the known property of heparin as an inhibitor of RNase.

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