Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Toad bladder epithelial cells were isolated under mild conditions in a calcium-free medium; they were found to exclude trypan blue, to consume oxygen, and to respond to vasopressin with an increased rate of oxygen consumption. Since isolated toad bladder epithelial cells are mostly spherical in shape, the cell diameter can be accurately measured with an ocular micrometer of an inverted microscope. Epithelial cells swelled by 29+/-3% in the presence of KCN. This cyanide-induced swelling of cells was prevented by amiloride or, alternatively, by replacing NaCl by equiosmotic amounts of mannitol in the Ringer's fluid. Cells incubated in the presence of vasopressin swelled by 10+/-2%. Vasopressin and KCN acted synergistically in enhancing cell volume. Ouabain caused cells to swell by 9+/-2%, and this effect was not additive to the swelling seen with vasopressin. These observations are in accord with the theory of Leaf and his associates, that the predominant effect of vasopressin is to enhance sodium entry into the transporting epithelial cells of the toad urinary bladder.
 ...
PMID:Action of vasopressin, ouabain, and cyanide on the volume of isolated toad bladder epithelial cells. 40 62

Freeze-fracture electron microscopy had previously revealed antidiuretic hormone-induced aggregates of intramembranous particles in amphibian urinary bladder. To investigate the effects of antidiuretic hormone (ADH) in another ADH-sensitive epithelium, namely, mammalian renal collecting ducts, freeze-fracture studies were carried out in Brattleboro homozygous rats. Collecting duct luminal membranes of ADH-treated homozygotes showed intramembranous particle clusters (117 +/- 17/100 micron2) that were loosely packed and that occurred on both exoplasmic (E) and protoplasmic (P) faces. Untreated, control homozygous rats had significantly less (3 +/- 1/100 micron2) clusters. Changes similar to those seen in ADH-treated rats were observed in water-deprived Wistar rats. The clustered particles differed from those seen in ADH-treated amphibian urinary bladder in that the latter occurred only on the P face and were more densely packed. Nevertheless, our observations suggest a common membrane effect for ADH action that may apply in mammals and amphibia alike.
 ...
PMID:Antidiuretic hormone-induced intramembranous alterations in mammalian collecting ducts. 72 93

Freeze-fracture electron microscopy demonstrates that vasopressin stimulation of isolated toad bladder alters the structure of the luminal membrane of granular cells. This alteration consists of an ordered aggression of intramembranous particles, and appears to be of functional significance, since the frequency of aggregation sites per area of membrane is closely correlated with vasopressin-induced osmotic water flow.
 ...
PMID:Vasopressin: induced structural change in toad bladder luminal membrane. 80 40

Freeze cleaving electron microscopy has shown that fusion of isolated secretory vesicles from bovine neurohypophyses was induced by Ca2+ in micromolar concentrations. Mg2+ and Sr2+ were ineffective. Mg2+ inhibited Ca2+-induced fusion. In suspensions containing secretory vesicles as well as sheets of cell membrane, release of vasopressin parallel to intervesicular fusion and fusion of secretory vesicles with sheets of cell membrane was observed after exposure to Ca2+. Mg2+ and Sr2+ were ineffective in replacing Ca2+ as trigger for fusion or vasopressin release. Intervesicular fusion and exocytotic profiles were observed when isolated neurohypophyses or neurosecretosomes were exposed to cold.
 ...
PMID:Fusion of neurohypophyseal membranes in vitro. 90 83

The available evidence suggests that hormones and neurophysins are associated exclusively with the neurosecretory granules, each of which contains approximately 6 times 10-4 molecules of each. Hormones and carrier proteins are complexed within the granules and the complexes are densely packed. The processes that keep the intragranular space in osmotic equilibrium with the axoplasm require further study. Freeze-fracture data, as well as studies in which histochemical methods for the detection of glycoproteins were used, suggest that the intragranular aspect of the granule membrane mostly resembles the extracellular half of the plasma membrane; on the other hand, the cytoplasmic aspects of plasma and granule membrane have similar characteristics, which may be important in permitting membrane fusion to take place prior to secretion. Little is known about the molecular species involved in this interaction between granule and plasma membrane, except that calcium is a cofactor in this process. Release is triggered in vivo by propagated action potentials which cause an influx of calcium into the secretory endings. Newly formed granules, and other granules located at the periphery of the endings are preferentially released. Irrespective of the type of stimulation of secretion, release involves the diffusion into the extracellular space of granule core constituents. The best evidence so far in support of this view comes from ultrastructural studies showing images of exocytosis, as well as from biochemical studies demonstrating that hormones and carrier proteins are secreted concomitantly in a great variety of experimental or clinical conditions, without an associated release of granule membrane constituents or of enzymes of cytoplasmic origin. Recovery mechanisms following secretion require new synthesis of granule constituents and restoration of the resting internal concentrations of potassium, sodium, and calcium. Membrane surface area is restored following exocytosis by compensatory endocytosis which involves indiscriminate uptake of extracellular medium into the secretory axon terminals. While much progress has been made in research on the cellular and subcellular processes that take place in neurons which produce, store, and secrete neurohypophyseal hormones and their carrier proteins, neurophysins, many pressing questions remain to be answered. New developments, such as organ culture of supraoptic nuclei94-96 and the recent isolation of a clone of mouse hypothalamic cells capable of synthesizing vasopressin and neurophysin,97 will hopefully allow some of these problems to be solved in the future.
 ...
PMID:A review on neurosecretory granules: their contents and mechanisms of release. 109 Nov 94

We have used the isolated perfused tubule technique, measurements of adenosine 3',5'-cyclic monophosphate (cAMP) content in single tubules, and freeze-fracture electron microscopy to study the basis of high vasopressin-independent (basal) osmotic water permeability (Pf) in the terminal inner medullary collecting duct (IMCD) of the rat. The results confirmed the observation that the basal Pf of the terminal IMCD is considerably higher than that of the initial IMCD. They also showed that the basal Pf of the terminal IMCD is regulated by in vivo factors related to water intake, such that a very high vasopressin-independent Pf can be induced in isolated tubules by prior in vivo thirsting. Tubules from thirsted rats did not display elevated urea permeabilities, nor did they exhibit measurable cAMP levels in the absence of exogenous vasopressin, indicating that the high basal Pf was not due to residual binding of vasopressin to its receptors. Freeze-fracture studies in thirsted rats demonstrated the presence of intramembrane particle (IMP) clusters in both initial and terminal IMCD, with more in the latter. Water loading of the rats suppressed the incidence of clusters almost entirely but did not fully suppress the basal Pf in the terminal IMCD, raising the possibility that a component of transepithelial water transport may occur independently of the vasopressin-regulated IMP clusters. On the basis of these results, we conclude that the vasopressin-independent Pf in the terminal IMCD can be stably elevated to very high levels in response to in vivo thirsting. This elevation appears to be due to a chronic conditioning effect mediated by unknown in vivo factors and is not due to the short-term cAMP-mediated regulatory effect of vasopressin.
 ...
PMID:Regulation of collecting duct water permeability independent of cAMP-mediated AVP response. 165 34

3,3'-diallyldiethylstilbestrol (DADES), a blocker of the facilitated diffusion of glucose, was found to interfere markedly with the hydrosmotic response to antidiuretic hormone and its related agonists. Frog urinary bladders were isolated and monitored for transmural net water flow. DADES was added either to the serosal or to the apical medium at concentrations ranging from 10(-4) M to 10(-6) M. Pretreatment for 30 min with apical 10(-4) M DADES drastically reduced the subsequent hydrosmotic response: (a) to oxytocin (4.4 x 10(-8) M) by 91.7 +/- 17.6% versus 6.2 +/- 7.8 in control; (b) to 8-bromo 3',5'-cyclic AMP by 93.5 +/- 19.4% versus 19.4 +/- 11.4%; (c) to serosal hyperosmolarity (mannitol 220 mOsm) by 99.3 +/- 0.5% versus 12.3 +/- 18.2%. This effect was dose-dependent. Inhibitory action of DADES was more effective on the apical side than on the serosal side (97.0 +/- 1.5 versus 45.8 +/- 10.8). Freeze-fracture studies revealed a modified distribution of the particles and unusual endocytotic pits and vesicles in the apical membrane of both granular and mitochondria-rich epithelial cells. These observations point to multiple and complex effects of the drug. Thus, it seems that DADES has numerous effects on urinary epithelium, which makes it a nonspecific inhibitor of water permeation. Conclusions on its use should therefore be drawn with suitable caution.
 ...
PMID:Inhibition of the hydrosmotic response to antidiuretic hormone by 3,3'-diallyldiethylstilbestrol (DADES). 250 75

Freeze-fracture electron microscopy reveals intramembrane particle arrays in basal membranes of granular epithelial cells as well as both upper and lower plasma membranes of the underlying basal cells in the toad urinary bladder. These particle arrays are morphologically indistinguishable from the luminal membrane aggregates which are known to be associated with antidiuretic hormone (ADH)-stimulated water transport. In both granular and basal cells particle arrays are frequently located in and/or around the openings of vesicular and/or tubular structures fused to the plasma membranes, suggesting that they may be transferred from the cytoplasm by membrane fusion. Quantification of cytoplasmic aggrephores in control granular cells shows that they can be numerous and as close to the basolateral membrane as they are with the luminal membrane, to which they are known to fuse and deliver aggregates upon ADH stimulation. Aggrephore-like tubules were also found in the basal cells. Particle array densities were quantified for 6 pairs of control and ADH-stimulated hemibladders. At least 1440 microns 2 area of plasma membrane for each membrane domain was examined. Results indicate that the presence of these particle arrays in granular and basal cell membranes is highly variable and that exposure to ADH does not cause a statistically significant increase in their frequency.
 ...
PMID:Intramembrane particle structures in epithelial cells of the toad urinary bladder: a quantitative freeze-fracture study. 250 77

The water permeability of collecting ducts is greatly increased by the antidiuretic hormone, vasopressin (VP). Freeze-fracture studies were carried out to test if this permeability increase is associated with the appearance of intramembrane particle (IMP) aggregates and whether increased doses of VP lead to an increase in the number and size of particle aggregates in the luminal membrane of principal cells in the isolated cortical collecting duct. Unstimulated cells expressed 17 +/- 6.5 particle aggregates per 100 microns 2. Stimulation with VP at concentrations of 20 or 200 microU/ml increased the number of particle aggregates significantly to 129 +/- 15.8 and 324 +/- 45.8, respectively. The size of the particle aggregates increased from 0.0012 microns 2 under control conditions to 0.025 microns 2 at 20 microU/ml VP and to 0.063 microns 2 at 200 microU/ml VP. In addition, the total area occupied by the IMP increased from 0.02 microns 2/100 microns 2 (controls) to 3.17% and 20.38% (after 20 and 200 microU ADH/ml, respectively). Particle aggregates were also observed in the luminal plasma membrane of isolated collecting ducts fixed immediately after dissection, resembling the in vivo status. These results demonstrate that a dose-dependent relationship exists between the concentration of the applied VP and the number of particle aggregates, as well as the size of the aggregates. Cytoplasmic tubular vesicles in fusion with the apical membrane were observed.
 ...
PMID:Vasopressin-induced intramembrane particle aggregates. A dose-response relationship in the isolated cortical collecting duct of the rabbit kidney. 280 60

The possible role of actin microfilaments in antidiuretic hormone (ADH)-induced increases in apical membrane water permeability was investigated in studies that evaluate inhibition by cytochalasin B of both permeability and membrane structural responses in the toad urinary bladder. Experiments were carried out in the absence of a transepithelial osmotic gradient to eliminate possible flow-induced distortions of the response. Measurements of osmotic water permeability after a brief tissue fixation with glutaraldehyde show that cytochalasin B reduces the permeability response to ADH by approximately one-third. Freeze-fracture electron microscopy indicates that the intramembrane particle aggregates, previously found to correlate closely with ADH-induced permeability, are reduced by about the same extent (28%) under these conditions. However, the frequency of apical membrane fusion events was not affected by cytochalasin B treatment. These results suggest that cytochalasin B treatment in the absence of an osmotic gradient alters the ADH-induced permeability through an effect on apical membrane aggregate frequency.
 ...
PMID:Cytochalasin B inhibition of toad bladder apical membrane responses to ADH. 314 Jun 72


1 2 Next >>