Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prostaglandin E biosynthesis and its effect on water permeability were investigated in the toad urinary bladder. Arginine vasopressin (1 mU/ml) increased prostaglandin E (PGE) biosynthesis from 0.5+/-0.1 to 5.0+/-0.4 pmol/min per hemibladder (mean +/-SEM, n= 8, P less than 0.001). Maximal vasopressin-stimulated PGE biosynthesis, 6.4+/-0.2 pmol/min per hemibladder, occurred at vasopressin concentrations in excess of 3 mU/ml. Half-maximal stimulation of PGE biosynthesis occurred at a vasopressin concentration of approximately 0.7 mU/ml, whereas half-maximal stimulation of water flow occurred at a vasopressin concentration of approximately 5 mU/ml. Vasopressin-stimulated PGE biosynthesis did not depend on water flow along an osmotic gradient or upon sodium transport. Thin-layer chromatographic analysis of the lipids released from hemibladders labeled with tritium-arachidonic acid revealed that vasopressin stimulates the release of arachidonic acid from intracellular lipid stores without affecting the percentage of free arachidonic acid converted to PGE. Neither cyclic AMP nor theophylline stimulated PGE biosynthesis although they mimic arginine vasopressin (AVP) in stimulating water permeability. Biosynthesis of PGE was inhibited by mepacrine, a phospholipase inhibitor, and by agents that inhibit arachidonic acid oxygenase. The inhibition of PGE biosynthesis resulted in augmented vasopressin- and theophylline-stimulated water flow, but had no effect on cyclic AMP-stimulated water flow. We interpret these results to mean that endogenous PGE inhibits basal and vasopressin-stimulated adenylate cyclase activity. In contrast to the effects of AVP on permeability and transport, AVP stimulates PGE biosynthesis by a mechanism that does not depend on an increase in cellular cyclic AMP levels. The water permeability response of the toad urinary bladder to vasopressin is inhibited by PGE synthesized by the bladder in response to vasopressin.
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PMID:Vasopressin-stimulated prostaglandin E biosynthesis in the toad urinary bladder. Effect of water flow. 19 20

1 Nicotinic acid and alloxanate inhibited water and electrolyte secretion in a dose-dependent fashion when added to the perfusate of the isolated saline-perfused pancreas of the cat stimulated by a supramaximal dose of secretin.2 There were no changes in the concentration of sodium or potassium secreted into the juice, but the anions exhibited changes which were related to flow rate. As the flow rate declined the chloride concentration increased with a reciprocal decrease in bicarbonate concentration.3 Nicotinic acid and alloxanate inhibited enzyme secretion stimulated by carbachol.4 Imidazole inhibited pancreatic electrolyte secretion, but stimulated amylase secretion. Atropine (0.14 muM) reduced the secretion of amylase but did not abolish the effect.5 Adenylate cyclase prepared from cat pancreas, was stimulated by the octapeptide of cholecystokinin-pancreozymin, secretin and sodium fluoride.6 Alloxanate strongly inhibited both basal and hormone-stimulated adenylate cyclase activity. Nicotinic acid and imidazole stimulated basal adenylate cyclase activity but had little effect on secretin-stimulated activity.7 Alloxanate, nicotinic acid and imidazole were all without effect on phosphodiesterase when tested in the presence of micromolar concentrations of adenosine 3',5'-monophosphate (cyclic AMP). At higher cyclic AMP concentrations (2 mM) alloxanate and nicotinic acid were without effect, whereas imidazole had a slight stimulatory effect at 10 mM which was more marked at 50 mM.8 Alloxanate (10 mM) strongly inhibited both basal and secretin-stimulated adenylate cyclase activity.9 It is concluded that the effects of nicotinic acid, alloxanate and imidazole on pancreatic secretion are not mediated entirely through their effects on the adenylate cyclase or phosphodiesterase enzyme systems.
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PMID:The effects of alloxanate, nicotinic acid and imidazole on secretory processes and the activities of adenylate cyclase and 3',5'-AMP phosphodiesterase in cat pancreas. 20 Feb 97

Resistance of the chronically diseased kidney to vasopressin has been proposed as a possible explanation for the urinary concentrating defect of uremia. The present studies examined the water permeability and adenylate cyclase responsiveness of isolated cortical collecting tubules (CCT) from remnant kidneys of uremic rabbits to vasopressin. In the absence of vasopressin the CCTs of both normal and uremic rabbits were impermeable to water. At the same osmotic gradient, addition of a supramaximal concentration of vasopressin to the peritubular bathing medium led to a significantly lower net water flux per unit length (and per unit luminal surface area) in uremic CCTs than in normal CCTs. Transepithelial osmotic water permeability coefficient, P(f), was 0.0232 +/-0.0043 cm/s in normal CCTs and 0.0059+/-0.001 cm/s in uremic CCTs (P < 0.001). The impaired vasopressin responsiveness of the uremic CCTs was observed whether normal or uremic serum was present in the bath. Basal adenylate cyclase activity per microgram protein was comparable in normal and uremic CCTs. Stimulation by NaF led to equivalent levels of activity in both, whereas vasopressin-stimulated activity was 50% lower in the uremic than in the normal CCTs (P < 0.025). The cyclic AMP analogue, 8-bromo cyclic AMP, produced an increase in the P(f) of normal CCTs closely comparable to that observed with vasopressin. In contrast, the P(f) of uremic CCTs was only minimally increased by this analogue and was not further stimulated by theophylline. These studies demonstrate an impaired responsiveness of the uremic CCT to vasopressin. This functional defect appears to be a result, at least in part, of a blunted responsiveness of adenylate cyclase to vasopressin. The data further suggest that an additional defect in the cellular response to vasopressin may exist, involving a step (or steps) subsequent to the formation of cyclic AMP.A unifying concept of the urinary concentrating defect of uremia is proposed which incorporates a number of hitherto unexplained observations on the concentrating and diluting functions of the diseased kidney.
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PMID:Functional profile of the isolated uremic nephron. Impaired water permeability and adenylate cyclase responsiveness of the cortical collecting tubule to vasopressin. 20 38

The objective of this paper is to assess current knowledge on the pharmacologic and presumed physiologic effects of prostaglandins (PGs) on water and ion transport in the human intestine, from data in the literature and results of authors' studies. PGs, when administered intraluminally or intravenously, induce a profuse net secretion of water and ions into the jejunum or ileum; there is evidence that this effect is unrelated to changes in motility but due to a direct interaction of PGs with mucosal transport processes. Relations of PGs to cholera toxin, gastrointestinal hormones and adenylate cyclase-cyclic AMP system are reviewed. We propose to consider PGs as one of the most convenient model for studying intestinal secretion in vivo in man, in view of the rapid onset, magnitude, reversibility and reproducibility of their striking effect on mucosal transport.
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PMID:The role of prostaglandins in the study of intestinal water and electrolyte transport in man. 21 32

PGE1 and PGE2 are known to interfere with the water permeability effect of vasopressin in toad bladder and kidney. It has been proposed that endogenous prostaglandin E (PGE), synthesized within cells of vasopressin-sensitive tissues, serves to modulate the permeability changes elicited by the neurohypophyseal hormone. Direct evidence in support of this hypothesis is as follows: vasopressin increases the biosynthesis of PGE2 in renal interstitial cells and in isolated toad bladder. In the latter, inhibition of vasopressin-induced synthesis of PGE by a variety of inhibitors results in a greater water permeability response to vasopressin. It appears that vasopressin has two effects in toad bladder and kidney: (i) it activates adenylate cyclase thereby increasing the concentration of adenosine 3',5' monophosphate (cyclic AMP), the nucleotide responsible for the resultant increase in water permeability; and (ii) it activates a phospholipase that serves to release arachidonic acid, the precursor of PGE2 from intracellular pools. The PGE derived from the arachidonic acid diminishes adenylate-cyclase activity, in consequence of which the response of the enzyme to vasopressin is modulated.
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PMID:Role of prostaglandin E (PGE) in the modulation of the action of vasopressin on water flow in the urinary bladder of the toad and mammalian kidney. 21 71

1. The effects of adrenalectomy on the adenylate cyclase--adenosine 3':5'-cyclic monophosphate (cyclic AMP) system of rat renal medulla were examined to evaluate the mechanism of the impaired water diuresis in glucocorticoid deficiency. 2. Concentrations of cyclic AMP in medullary tubules from adrenalectomized rats were significantly higher than in the tubules from control animals both in the presence and absence of antidiuretic hormone. 3. This abnormality was corrected by the treatment in vivo of the adrenalectomized rats with dexamethasone, but addition of this drug to the incubation medium did not abolish the differences in cyclic AMP between tubules from adrenalectomized and normal rats. 4. The activity of adenylate cyclase or cyclic AMP phosphodiesterase in vitro was not affected by adrenalectomy. 5. In glucocorticoid deficiency, the concentration of cyclic AMP in medullary tubules is increased both with and without antidiuretic hormone. This abnormality may render medullary tubules more permeable to water and may underlie the impaired water diuresis in glucocorticoid deficiency.
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PMID:Effects of glucocorticoid deficiency on renal medullary cyclic adenosine monophosphate of rats. 21 86

Vasopressin increases the permeability of receptor cells to water and, in tissues such as toad bladder, to solutes such as urea. While cyclic AMP appears to play a major role in mediating the effects of vasopressin, there is evidence that activation of the water permeability system and the urea permeability system involves separate pathways. In the present study, we have shown that inhibitors of oxidative metabolism (rotenone, dinitrophenol, and methylene blue) selectively inhibit either vasopressin-stimulated water flow or vasopressin-stimulated urea transport. There was no inhibition, however, when exogenous cyclic AMP was substituted for vasopressin, and little to no inhibition when the potent analogue 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) was employed. Rotenone had no effect on adenylate cyclase activity or cyclic AMP levels within the cell; dinitrophenol decreased adenylate cyclase activity minimally. Additional studies with vinblastine and nocodazole, inhibitors of microtubule assembly, demonstrated an inhibition of vasopressin and cyclic AMP-stimulated water flow but showed no effect on urea transport. We would conclude that water and urea transport, as examples of hormone-stimulated processes, have different links to cell metabolism, and that in addition to cyclic AMP, a non-nucleotide pathway may be involved in the action of vasopressin.
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PMID:Effect of metabolic inhibitors on vasopressin-stimulated transport systems in the toad bladder. 22 66

The role of dibutyryl cyclic adenosine 3',5'-monophosphate (db cAMP) in influencing the water content of the cat's gray and white matter was evaluated by intracoritcal injection of 20 micrio L of 2 x 10(-1) to 2 x 10(-6)M solution of db cAMP. Cholera toxin, a stimulator of adenylate cyclase, also was tested. Concentrations of db cAMP less than 10(-3)M failed to produce significant change in brain water content, while concentrations greater than 10(-2)M produced 31.5% +/- 8% and 17.3% +/- 3.6% increases in white matter volume, respectively (P less than .05). Cholera toxin did not increase brain water levels. These results are discussed in relation to the pathophysiology of brain edema.
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PMID:Dibutyryl cyclic adenosine 3',5'-monophosphate: its role in regulation of cat brain extracellular fluid. 22 44

Certain epithelial cell lines have morphologic, physiologic, biochemical and pharmacologic characteristics of transporting epithelia from intact organs. In this paper we show that dibutyryl cyclic AMP, 5' AMP, adenosine and cyclic AMP phosphodiesterase inhibitors stimulate hemicyst formation by the dog kidney cell line MDCK. It is suggested that this effect is explained by elevation of intracellular cyclic AMP levels by means of an exogenous non-metabolizable source of cyclic AMP, phosphodiesterase inhibition or adenyl cyclase stimulation. Since hemicyst formation is in part due to transepithelial fluid transport, these findings raise the possibility that this fraction might be modulated by cAMP in an established cell line. We believe that cultured epithelial cells may provide an exploitable model system to investigate at the cellular and subcellular levels, the mechanism by which cyclic AMP modifies water and solute movements across epithelia.
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PMID:Hemicyst formation stimulated by cyclic AMP in dog kidney cell line MDCK. 22 13

Addition of the 3-series fatty acid precursor (icosapentaenoic acid, IPA), its endoperoxide [prostaglandin (PG)H(3)], or thromboxane A(3) to human platelet-rich plasma (PRP) does not result in aggregation of the platelets. In fact, preincubation of human PRP with exogenous PGH(3) actually inhibited aggregation by increasing platelet cyclic AMP concentrations. PGH(3) undergoes rapid spontaneous degradation to PGD(3) in human PRP. The PGD(3) so formed is adequate to account for the increase of platelet cAMP and inhibition of aggregation. Furthermore, addition of PGD-specific antisera to human PRP blocked the platelet inhibitory activity of exogenous PGH(3). PGD(3) has considerable potential as a circulating antithrombotic agent. Pretreatment of human PRP with the adenylate cyclase inhibitor 2',5'-dideoxyadenosine blocked the increase of platelet cyclic AMP and the inhibition of aggregation normally produced by PGI(2), PGE(1), PGD(2), PGH(3), and PGD(3). Furthermore, the dideoxyadenosine unmasked a direct but moderate reversible aggregatory effect in response to the subsequent addition of PGH(3). Similarly, the dideoxyadenosine markedly enhanced the aggregation produced by exogenous PGH(2). IPA is readily incorporated into tissue lipids but proved to be a poor substrate for kidney, blood vessel, or heart cyclooxygenase. IPA was previously shown to be a poor substrate for platelet cyclooxygenase. IPA is readily deacylated from the renal phospholipid pool in response to bradykinin, a substance that also stimulates the release of arachidonic acid. A diet that relies primarily on cold-water fish, as in the case of the Greenland Eskimos, lowers endogenous arachidonic acid and markedly increases the IPA content of tissue lipids. Thus, because IPA has the potential to act as an antagonist with arachidonic acid for platelet cyclooxygenase and lipoxygenase, the simultaneous release of IPA could suppress any residual arachidonic acid conversion to its aggregatory metabolites.
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PMID:Triene prostaglandins: prostaglandin D3 and icosapentaenoic acid as potential antithrombotic substances. 23 Apr 92


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