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

It has been assumed from studies in toad bladder that antidiuretic hormone (ADH)-stimulated particle delivery to the luminal membrane is mediated by particle-carrying tubular structures (aggrephores). We report studies in frog and toad urinary bladder showing that vesicles, rather than aggrephores, appear to play the major role in particle delivery in the frog and that vesicle and aggrephore delivery proceed in parallel in the toad. Our principal evidence for this view is that in the frog, transmission electron microscopy shows virtually no fused aggrephores. Supporting evidence includes the following. 1) Freeze-fracture studies show that the diameters of fusion events delivering particles can be quite small, indicating that they are formed by fused vesicles rather than fused aggrephores. 2) A significant population of small fusion events is also seen in the toad, along with larger fusion events related to both aggrephores and large vesicles. 3) Surface aggregate areas in both species are small, consistent with vesicular delivery. 4) Freeze-fracture replicas indicate delivery from shallow pits. We propose a system of transport of particles in which aggrephores act largely as intermediate storage organelles in the frog and as storage and fusion organelles in the toad.
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PMID:Role of vesicular transport in ADH-stimulated aggregate delivery. 314 70

Freeze-fracture electron microscopy of the toad urinary bladder indicates that distinctive intramembrane particle aggregates are responsible for the increase in apical membrane water permeability that occurs with vasopressin (VP) stimulation. In unstimulated bladders the aggregates occur in the cytoplasm of the cells in tubular membrane structures now called aggrephores. After stimulation by VP, aggrephores are shuttled to the surface and fuse with the apical membrane. It is suggested by structural observations and by measurements of membrane capacitance that the area of aggregates inserted into the apical membrane is much greater than previously suspected because many aggregates remain in the wall of the fused aggrephores. The area of the aggregates in a stimulated bladder is sufficiently large for these structures to represent an organized array of water channels that mediates the change in apical membrane permeability. Work with antibodies supports the concept that these channels are not always resident in the apical membrane but become inserted only after stimulation by the hormone VP.
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PMID:Membrane structural studies of the action of vasopressin. 389 54

Vasopressin increases the water permeability of the luminal membrane of the toad bladder epithelial cell. This change in permeability correlates with the occurrence in luminal membranes of intramembrane particle aggregates, which may be the sites for transmembrane water flow. Withdrawal of vasopressin is ordinarily associated with a rapid reduction of water flow to baseline values and a simultaneous disappearance of the particle aggregates. The bifunctional imidoesters dithiobispropionimidate (DTBP) and dimethylsuberimidate (DMS), which cross-link amino groups in membrane proteins and lipids, slow the return of water flow to baseline after vasopressin withdrawal. Cross-linking is maximal at pH 10, and is reduced as pH is lowered. Freeze-fracture studies show persistence of luminal membrane particle aggregates in cross-linked bladders and a reduction in their frequency as water flow diminishes. Fusion of aggregate-containing cytoplasmic tubular membrane structures with the luminal membrane is also maintained by the imidoesters. Reductive cleavage of the central S-S bond of DTBP by beta-mercaptoethanol reverses cross-linking, permitting resumption of the rapid disappearance of the vasopressin effect. Bladders that have undergone DTBP cross-linking and beta-mercaptoethanol reduction respond to a second stimulation by vasopressin. Thus, the imidoesters provide a physiologic and reversible means of stabilizing normally rapid membrane events.
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PMID:Stabilization of vasopressin-induced membrane events by bifunctional imidoesters. 626 63

Most magnocellular neurosecretory cells that terminate in the posterior pituitary secrete either vasopressin, oxytocin, or enkephalin. Intracellular injection of the fluorescent dye Lucifer Yellow into single magnocellular neurons in slices of rat hypothalamus resulted in dye transfer between these cells. Freeze-fracture replicas of these cells occasionally revealed gap junctions, which presumably contain channels that mediate the dye coupling. These two independent techniques strongly suggest that some mammalian neuropeptidergic cells are electrotonically coupled, providing a possible means for recruitment and synchronization of their electrical activity.
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PMID:Dye transfer through gap junctions between neuroendocrine cells of rat hypothalamus. 746 93

The urinary bladder of the aquatic toad Xenopus laevis is known to exhibit a low permeability to water and a poor sensitivity to antidiuretic hormone. In order to precise the characteristics and the specific cellular mechanisms of this reduced hydro-osmotic response we used a sensitive volumetric technique to monitor net water flow and studied the correlation between the antidiuretic hormone (ADH)-induced net water flow and the fine ultrastructural appearance of the urinary bladder epithelium. Transmural net water flow was entirely dependent on the osmotic gradient across the preparation and not on the hydrostatic pressure difference. We observed the existence of a low but significant hydro-osmotic response to arginine vasopressin. Freeze-fracture electron microscopy demonstrated the presence of typical aggrephores in the subapical cytoplasm. The response to the hormone was accompanied by the appearance of typical intramembrane aggregates into the apical plasma membrane. Water permeability increase and apical aggregate insertion were both slowly but fully reversible. Except for the multilayered structure of the epithelium and the particularly low response to antidiuretic hormone, all the studied permeability and ultrastructural characteristics of the bladder were thus very similar to those observed in other sensitive epithelia such as the amphibian bladder and skin and the mammalian collecting duct which exhibit a high hydro-osmotic response to the hormone.
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PMID:Antidiuretic response in the urinary bladder of Xenopus laevis: presence of typical aggrephores and apical aggregates. 805 83

Prolonged drought, necessitating conservation of water, is one of the major environmental challenges faced by many Australian marsupials. Radioactive isotopes of water and sodium were used to assess the ability of two species of marsupial wallabies to maintain water and electrolyte balance during periods of extreme water deprivation in the arid Pilbara region of Western Australia. The spectacled hare-wallaby, Lagorchestes conspicillatus, has the lowest mass-specific rate of water turnover at 27.5 ml.kg(-0.82).day(-1) yet reported for any mammal and was two to three orders of magnitude lower than that of the Rothschild's rock-wallaby, Petrogale rothschildi. Studies of renal function show that the hare-wallaby conserves water by producing a highly concentrated urine under the influence of lysine vasopressin (LVP), the anti-diuretic hormone (ADH) in macropodid marsupials. In contrast, rock-wallabies show unusual renal responses to water deprivation, with no change in LVP levels and a limited response to water deprivation involving a reduction in renal plasma flow and glomerular filtration rate, with no significant change in tubular function. Both species are able to maintain water and electrolyte homeostasis during periods of drought, highlighting the efficacy of their differing adaptive solutions to the problem of water scarcity, although the hare-wallaby is superior to the rock-wallaby in this respect. Rock-wallabies appear to rely primarily on behavioural rather than physiological responses for their survival in the Pilbara and appear to be more vulnerable to extinction in the event of significant habitat modification. The secure nature of their rock habitat, however, means that they have suffered less than hare-wallabies in the recent past.
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PMID:Water and electrolyte homeostasis and kidney function of desert-dwelling marsupial wallabies in Western Australia. 1126 23

Beacon is a 73-amino acid peptide encoded by a novel gene in the hypothalamus of Israeli sand rat Psammomys obesus. Reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemical techniques were used to investigate the presence of beacon mRNA and the distribution of beacon-immunoreactivity (irBC) in the hypothalamus of ICR mice. RT-PCR experiments revealed beacon mRNA in the mouse hypothalamus. Using a rabbit polyclonal antiserum directed against the synthetic C-terminal peptide fragment (47-73), irBC was detected in the mouse hypothalamus and pituitary. In the hypothalamus, irBC was concentrated in perikarya of the supraoptic (SO), paraventricular (PVH) and accessory neurosecretory nuclei and in cell processes of the median eminence and pituitary stalk. In the pituitary, irBC was noted mainly in the posterior lobe. Double-labeling the hypothalamic sections with guinea-pig vasopressin-antiserum or mouse monoclonal oxytocin-antibody and beacon-antiserum revealed that <30% of vasopressin-immunoreactive neurons and nearly all oxytocin-immunoreactive neurons in the PVH and SO were irBC. The result shows the presence of beacon mRNA in the mouse hypothalamus, and the distribution of irBC is distinctively different from that reported in the hypothalamus of Psammomys obesus, but similar to that of the Sprague-Dawley rats described in our earlier study. More interestingly, Blast search uncovered a 73-amino acid peptide, human ubiquitin-like 5, which has the same exact sequence as beacon. Thus, irBC observed in the mouse brain could be that of ubiquitin-like 5.
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PMID:Beacon/ubiquitin-like 5-immunoreactivity in the hypothalamus and pituitary of the mouse. 1293 56


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