The effects of experimental uremia in rats on duodenal VIP levels and the interaction of VIP with duodenal epithelial cells

1989 ◽  
Vol 9 (2) ◽  
pp. 207-212
Author(s):  
M. D. Fernández-Moreno ◽  
E. Arilla ◽  
J. C. Prieto
Keyword(s):  
Epithelial Cells ◽  
Cyclic Amp ◽  
Vasoactive Intestinal Peptide ◽  
Binding Affinity ◽  
Specific Binding ◽  
The Other ◽  
Receptor Level ◽  
Vip Receptors ◽  
Other Hand

The effects of experimental uremia on the concentration of vasoactive intestinal peptide (VIP) in duodenum as well as on the interaction of this neuropeptide with the corresponding epithelial cells were studied in rats. Duodenal VIP concentration was significantly decreased in uremic rats as compared to control animals. The specific binding of VIP to duodenal epithelial cells increased in rats with uremia due to an increase in the number of VIP receptors rather than a change in the binding affinity or in the extent of VIP degradation. On the other hand, the efficacy but not the potency of VIP upon cyclic AMP generation varied in parallel to that observed at the receptor level.

Interaction of vasoactive intestinal peptide with rat small intestinal epithelial cells after intestinal resection

1985 ◽  
Vol 5 (7) ◽  
pp. 559-566 ◽  
Author(s):  
José L. Diaz-Juarez ◽  
Guillermo Bodega ◽  
Eduardo Arilla ◽  
Juan C. Prieto
Keyword(s):  
Epithelial Cells ◽  
Cyclic Amp ◽  
Vasoactive Intestinal Peptide ◽  
Intestinal Epithelial Cells ◽  
Binding Capacity ◽  
Specific Binding ◽  
Intestinal Resection ◽  
Intestinal Epithelial ◽  
Cyclic Amp Accumulation ◽  
Small Intestinal

Specific binding of vasoactive intestinal peptide (VIP) and VIP-stimulated cyclic AMP accumulation were studied in small intestinal epithelial cells (both of crypt and villous levels) 3, 7 and 14 d after a 60% resection of the small intestine. The affinity, but not the binding capacity, of VIP receptors decreased during the adaptive hyperplastic response. Basal cyclic AMP levels were similar in cells of both control and resected rats. Resection induced a decrease of potency, but not of efficiency, of VIP on the stimulation of cyclic AMP accumulation.

Carbachol-induced down-regulation of high-affinity receptors for vasoactive intestinal peptide

1989 ◽  
Vol 257 (3) ◽  
pp. G402-G408
Author(s):  
M. Murakami ◽  
R. Vinayek ◽  
R. T. Jensen ◽  
J. D. Gardner
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Response Curve ◽  
Cholinergic Receptors ◽  
The Other ◽  
Tetraacetic Acid ◽  
Muscarinic Cholinergic Receptors ◽  
Pancreatic Acini ◽  
Vip Receptors ◽  
High Affinity ◽  
Muscarinic Cholinergic

When dispersed acini from guinea pig pancreas are first incubated with carbachol, the subsequent binding of 125I-vasoactive intestinal peptide (VIP) is inhibited during a second incubation. This inhibitory action of carbachol on binding of 125I-VIP depends on time, temperature, and the concentration of carbachol in the first incubation and can be blocked by atropine. First incubating acini with A23187, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), cholecystokinin octapeptide, bombesin, or 12-O-tetradecanoylphorbol-13-acetate does not alter binding of 125I-VIP. Adding EGTA to the first incubation medium abolishes the effect of carbachol on binding of 125I-VIP. In control acini or acini first incubated with carbachol, approximately half of the bound 125I-VIP can be stripped by acetic acid. 125I-VIP interacts with two distinct classes of receptors on pancreatic acini. One has a high affinity for VIP (Kd, 1 nM); the other has a low affinity for VIP (Kd, 2 microM). First incubating acini with carbachol decreases the number but not the affinity of high-affinity VIP receptors with no change in the number or affinity of low-affinity VIP receptors. Pancreatic acini possess two classes of muscarinic cholinergic receptors: one has a high affinity (Kd, 4 microM) and the other has a low affinity (Kd, 698 microM) for carbachol. The dose-response curve for carbachol-induced inhibition of binding of 125I-VIP and that for occupation of low-affinity muscarinic cholinergic receptors by carbachol are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Propranolol, atenolol, and trifluoperazine reduce the spontaneous occurrence of meiotic diploid products in Saccharomyces cerevisiae

1982 ◽  
Vol 2 (11) ◽  
pp. 1299-1303
Author(s):  
S Sora ◽  
M Bianchi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cyclic Amp ◽  
Meiotic Division ◽  
Direct Interaction ◽  
The Other ◽  
Crucial Point ◽  
Other Hand ◽  
Common Effect ◽  
Spontaneous Frequency ◽  
Spontaneous Occurrence

The effect of atenolol, propranolol, trifluoperazine, and caffeine on the occurrence of meiotic diploid and disomic products in Saccharomyces cerevisiae was investigated. We demonstrated that atenolol, propranolol, and trifluoperazine reduce the occurrence of meiotic diploid products and that propranolol also slightly decreases the spontaneous frequency of disomics. On the other hand, caffeine appears to be a powerful inducer of diploid meiotic products, but also shows a lesser effect on disomic induction. Since spontaneous or caffeine-induced diploids arise from a failure of the second meiotic division, it appears that the target of these drugs is at the beginning of the second meiotic division. The only common effect of trifluoperazine and propranolol, mainly investigated in mammals, was an inhibition of calmodulin activity via direct interaction. We tend, therefore, to believe that calmodulin activity must be a crucial point for the second meiotic division to begin. The increased induction of diploids, due to caffeine, may be interpreted as a consequence of an increased cyclic AMP level.

The Importance of Mesenchymal Factors in the Differentiation of Chick Epidermis

Development ◽  
1961 ◽  
Vol 9 (3) ◽  
pp. 370-384
Author(s):  
C. B. McLoughlin
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Squamous Epithelium ◽  
The Other ◽  
Β Cells ◽  
Preen Gland ◽  
Other Hand ◽  
Stratified Squamous Epithelium

It is well established that in the developing chick the underlying mesenchyme initiates the appearance of specific epidermal derivatives, e.g. feathers (Sengel, 1956), claws (Cairns & Saunders, 1954), and the preen gland (Gomot, 1958). On the other hand, it is not yet known to what extent the epidermis is independent of mesenchymal intervention for its basic differentiation into a stratified, squamous epithelium. Sobel's (1958) work on the 8-day chick pituitary suggests that the differentiation and multiplication of certain epithelial cells cannot proceed in the absence of mesenchymal elements. She found that the isolated epithelial cells of the hypophysial rudiment survived but were unable to differentiate or multiply; when associated with perichondrial fibroblasts, however, they resumed mitosis and produced typical α and β cells. In the first part of the present investigation, experiments were made to see whether the embryonic epidermis, like the hypophysial epithelium, requires the resence of fibroblasts to enable it to grow and differentiate, or whether it can proliferate, acquire its characteristic squamous structure and keratinize, when isolated and cultivated in the absence of connective tissue.

The Ability to Differentiate, and the Size of Regenerated Cells, after repeated Regeneration in Spongilla lacustris

1953 ◽  
Vol s3-94 (26) ◽  
pp. 177-184
Author(s):  
H. V. BRONDSTED
Keyword(s):  
Epithelial Cells ◽  
The Body ◽  
The Other ◽  
Entire Body ◽  
Other Hand ◽  
The Individual ◽  
Basal Epithelial Cells

The findings presented here have a bearing on regeneration in general. They show that even in simply organized animals, the number of totipotent cells which are able to differentiate decreases as the individual ages. In older specimens it takes longer for the totipotent cells to differentiate than in younger ones; at the same time the nuclear and cytoplasmic volume of these cells is reduced. The expanded basal epithelium of sponges germinating from gemmules is an organ necessary to establish the tension in the body which is indispensable for the functioning of the sponge. Sponges that have germinated from gemmules can be forced to regenerate a basal epithelium. The materials for this regeneration is furnished by the archaeocytes, which are embryonic, totipotent amoebocytes. The number of archaeocytes that are able to perform this regeneration decreases with time, i.e. as the differentiation of the entire body proceeds. On the other hand, the ability of the sponge to expand repeatedly on its own basal epithelium after being pushed away from it is limited only by the onset of cytolysis. The ability of the archaeocytes to regenerate new typical basal epithelial cells is reduced after repeated regeneration. The size of both nucleus and cytoplasm is reduced more and more during repeated regeneration. The nucleo-cytoplasmic ratio is thus kept fairly constant.

Functional Pool of Cyclic Adenosine 3',5'-Monophosphate in Rabbit Platelets

1983 ◽  
Vol 49 (01) ◽  
pp. 008-012 ◽  
Author(s):  
Shuichi G Hashimoto
Keyword(s):  
Plasma Membrane ◽  
Cyclic Amp ◽  
Binding Capacity ◽  
Binding Activity ◽  
The Other ◽  
Rabbit Platelet ◽  
Platelet Membranes ◽  
Other Hand ◽  
Fraction I ◽  
Induced Aggregation

SummaryAccumulation of the newly formed 14C-cyclic adenosine 3',5’-monophosphate (cyclic AMP) was found in the P1 (1.0) fraction, i. e. a platelet plasma membrane fraction which was obtained from 14C-adenine-labeled platelets. On the other hand, total cyclic AMP as determined simultaneously was located mainly in the platelet soluble fraction. Furthermore, the highest value of the cyclic AMP-binding capacity was found in the P1 (1.0) fraction. The cyclic AMP-binding activity of platelet membranes was attributed to two proteins with molecular weights of approximately 48,000 and 68,000.The treatment of 14C-adenine-prelabeled platelets with thrombin (1 unit per ml) led to about 40% decrease in the newly formed 14C-cyclic AMP level and 18% reduction of 14C-adenosine triphosphate level in whole platelets within 10 sec. On the other hand, the 14C-cyclic AMP level in the P, fraction decreased by about 80% of the control value while the total cyclic AMP in this fraction was almost unchanged. This rapid and striking fall in the membrane 14C-cyclic AMP level could be correlated with the more than 2fold stimulation of the membrane-bound cyclic AMP phosphodiesterase, together with the more than 20% inhibition of both the cyclic AMP-binding capacity and the adenyl cyclase in platelet membranes by thrombin treatment. These observations suggest the possibility that functional pool of cyclic AMP related to thrombin-induced aggregation is located in rabbit platelet plasma membrane.

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