Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of iontophoretically applied Na+-, K+-dependent adenosinetriphosphatase (Na+,K+-ATPase) (EC 3.6.1.3) inhibitors (ouabain, digitoxin, digitoxigenin, strophanthin K, strophanthidin, thevetin A and B, ethacrynate, and harmaline) on the depression of rat cerebral cortical neurones by noradrenaline, 5-hydroxytryptamine, and histamine have been studied. The inhibitors antagonized depressions of spontaneously active neurones evoked by these amines, but not those evoked by gamma-aminobutyric acid, adenosine, adenosine 5'-monophosphate, or calcium. The antagonistic potencies of the various inhibitors appeared to be proportional to their known potencies as inhibitors of Na+, K+-ATPase. The data therefore support the hypothesis that amines depress central neurones by activating an electrogenic sodium pump.
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PMID:Antagonism of biogenic amine-induced depression of cerebral cortical neurones by Na+, K+-ATPase in inhibitors. 14 20

Cyclic AMP and its dibutyryl derivative inhibit neuronal firing of the labellar sugar sensitive receptor of the blowfly when applied in conjunction with the stimulant sucrose. Furthermore, simultaneous application of aminophylline (phosphodieterase inhibitor) and sucrose or in combination with cyclic AMP caused a similar depression of the sugar receptors response. In contrast, dibutyryl cyclic GMP elicited an increase in sugar receptor firing when applied with sucrose to sugar receptor. Either 5'-AMP or 5'-GMP in combination with sucrose had no discernable effect on the sugar receptors response. Different ratio combinations of cyclic AMP and dibutyryl cyyclic GMP showed the striking inhibitory effect of cyclic AMP upon the dibutyryl cyclic GMP elicited increases in receptor firing frequency. Therefore, it is suggested that these two nucleotides may be mediating different but complimentary aspects of sugar receptor function in a push-pull manner.
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PMID:Apparent opposing effects of cyclic AMP and dibutyryl cyclic GMP on the neuronal firing of the blowfly chemo-receptors. 18 Oct 76

Insulin accelerates the entry of glucose and amino acids into muscle cells by acting upon the 'carrier-facilitated' transport mechanism. For glucose this process is passive and leads to equilibration of intracellular and extracellular concentrations. In heart muscle, glucose transport is a rate-limiting step for glucose uptake. During hypoxia and ischemia the heart turns to anaerobic glycolysis for energy production and therefore, maximal glucose transport becomes important. Insulin is necessary to insure proper protein synthesis, probably at the level of membrane-bound polyribosomes. However, during myocardial hypoxia, insulin alone cannot restore the associated depression in protein synthesis. Although insulin hyperpolarizes the cell, a change in the ratio of intracellular to extracellular activities of potassium is not its primary mode of action. An insulin-induced configurational change in the plasma membrane could simultaneously account for the effects of insulin on sodium and potassium permeability and the action on facilitated transport. Intracellular levels of cyclic adenylate may be reduced by insulin in adipose tissue because of inhibition of adenyl cyclase or stimulation of phosphodiesterase. However, at this time there is little evidence that insulin alters cyclic AMP levels in the heart. Insulin secretion is depressed in patients with heart disease in proportion to the reduction of cardiac index sustained. Since the ischemic heart is dependent upon glucose as the major fuel, insulin lack may deprive the heart of adequate substrate.
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PMID:Insulin: fundamental mechanism of action and the heart. 18 67

Vasopressin increases the permeability of the total urinary bladder, an analogue of the mammalian renal collecting duct, to water and small solutes, especially the amide urea. We have observed that three general anesthetic agents of clinical importance, the gases methoxyflurane and halothane and the ultrashortacting barbiturate methohexital, reversibly inhibit vasopressin-stimulated water flow, but do not depress permeability to urea, or the the lipophilic solute diphenylhydantoin. In contrast to their effects in vasopressin-treated bladders, the anesthetics do not inhibit cyclic AMP-stimulated water flow, consistent with an effect on vasopressin-responsive adenylate cyclase. The selectivity of the anesthetic-induced depression of water flow suggests that separate adenylate cyclases and cyclic AMP pools may exist for control of water and urea permeabilities in to toad bladder. Furthermore, theophylline's usual stimulatory effect on water flow, but not its effect on urea permeability, was entirely abolished in methoxyflurane-treated bladders, suggesting that separate phosphodiesterases that control water and urea permeabilities are present as well. We conclude that the majority of water and urea transport takes place via separate pathways across the rate-limiting luminal membrane of the bladder cell, and that separate vasopressin-responsive cellular pools of cyclic AMP appear to control permeability to water and to urea.
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PMID:Selective inhibition of osmotic water flow by general anesthetics to toad urinary bladder. 18 13

1. Responses of cerebral cortical neurones to the microiontophoretic application of acetylcholine, noradrenaline, cyclic adenosine 3',5'-monophosphate (cyclic AMP) and cyclic guanosine 3',5'-monophosphate (cyclic GMP) were examined.2. The application of acetylcholine and cyclic GMP to identified pyramidal tract neurones resulted in an increased frequency of firing in a large number of cells. Upon application of both substances to cells which could not be identified as pyramidal tract cells, a reduction in the frequency of spontaneous firing was sometimes observed.3. Careful current controls had no effect on the cells discussed here, indicating that the observed responses were not due to the iontophoretic currents. Also, the electro-osmotic ejection of cyclic GMP (outward current) produced similar changes of cell firing to those which followed iontophoretic application (inward current).4. The microiontophoretic application of atropine resulted in a blockade of acetylcholine responses while leaving responses to cyclic GMP unaffected. This suggests that cyclic GMP was not acting indirectly by releasing acetylcholine from presynaptic endings.5. Ejection of cyclic GMP from solutions containing calcium ions produced responses comparable to those produced by cyclic GMP alone. It is unlikely therefore that cyclic GMP was causing excitation by chelating calcium.6. Applications of noradrenaline and cyclic AMP produced a reduction in the spontaneous discharge rate of most neurones tested.7. Phosphodiesterase inhibitors such as ICI 63,197 caused a potentiation of the noradrenaline responses of pyramidal tract neurones.8. 5'-adenosine monophosphate produced a powerful depression of all cells to which it was applied. This action was blocked by aminophylline, suggesting the effect was mediated through an adenosine receptor. Responses to cyclic AMP were usually not abolished, but were reduced by about 50% in amplitude.9. These results are consistent with the hypothesis that cyclic AMP may mediate some neuronal effects of noradrenaline and cyclic GMP may mediate some effects of acetylcholine. The results are also consistent with the suggestion that the two nucleotides may sometimes mediate opposite cellular responses to humoral stimuli.
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PMID:Microiontophoretic studies of the effects of cylic nucleotides on excitability of neurones in the rat cerebral cortex. 19 28

A radioimmunoassay for cyclic AMP has been developed using protein A containing staphylococci as an immunoabsorbent. Protein A containing heat-killed staphylococci (Cowan I) are coated with rabbit antiserum raised against the 2'-O-succinyl derivative of cyclic AMP coupled to human serum albumin. After washing with a Tween 20 containing buffer, antibody coated staphylococci are diluted with heat-killed staphylococci devoid of protein A (staphylococcus epidermidis) and mixed with [125I]-2'-O-succinyl cyclic AMP tyrosine methyl ester, standards or unknowns. At the end of the incubation, separation of bound and free labelled antigen is achieved by bound and free labelled antigen is achieved by centrifugation. The results are comparable to those obtained with a precipitation assay using polyethylenglycol 6000. Acetylation prior to radioimmunoassay increases sensitivity about 80-fold. 50% depression of zero dose binding occurs at 15--16 femtomoles acetylated cyclic AMP. The crossreactivity with cyclic GMP, ATP, ADP, 5'-AMP and adenosine is extremely low. The present technique is an attractive alternative to the second antibody method or polyethylenglycol precipitation.
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PMID:Solid phase radioimmunoassay for cyclic AMP using staphylococcal protein A-antibody adsorbent. 19 25

Intravenously or iontophoretically applied diazepam potentiated the depressant action of iontophoretically applied 5'-AMP on the spontaneous firing of rat cerebral cortical neurons. This potentiation of purinergic depression may be a result of the previously reported inhibition by diazepam of uptake of adenosine into brain tissues.
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PMID:Diazepam potentiation of purinergic depression of central neurons. 22 11

Ticlopidine, when orally administered to rats, resulted in activation of basal and prostaglandin E1 (PGE1)-stimulated adenylate cylase activity through increase in affinity of the cyclase in platelet membrane to PGE1, although it failed to affect adenosine- or sodium fluoride-stimulated activity of the enzyme. In washed platelets, Ticlopidine also activated basal and PGE1-stimulated activity of the cyclase and prevented reduction in the cyclase activity caused by low concentrations of PGE2. Furthermore, Ticlopidine inhibited malondialdehyde formation in platelets induced by thrombin but failed to inhibit that caused by exogenous arachidonic acid. Adenosine 3',5'-cyclic monophosphate (c-AMP): phosphodiesterase activity of platelet lysate was not significantly affected by Ticlopidine treatment. These findings indicate that Ticlopidine inhibits platelet aggregation and prostaglandin synthesis from endogenous substrate through activating basal and PGE1-stimulated activity of the cyclase, preventing PGE2-induced depression of the cyclase activity and thus increasing platelet c-AMP level.
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PMID:Mode of action of ticlopidine in inhibition of platelet aggregation in the rat. 22 22

Adenosine and AMP (5'-adenosine monophosphate) applied by microiontophoresis produced depression of neuronal firing rates in cerebral cortex. A number of antidepressant drugs including examples which are known not to affect noradrenaline uptake systems, potentiated the depressant purine effects. Noradrenaline responses were unaffected or reduced. Purines may therefore be important in the mechanism of action of antidepressant drugs.
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PMID:Antidepressant drugs potentiate suppression by adenosine of neuronal firing in rat cerebral cortex. 43 90

We have previously demonstrated that bactericidal activity and superoxide anion (O2-) production are depressed concomitantly in polymorphonuclear leukocytes (PMNs) following thermal injury in a guinea pig model, and the bactericidal defect is related to elevation of intracellular cyclic-3',5'-adenosine monophosphate (cAMP). The purpose of the present investigation was to determine the relationship between elevation of intracellular cAMP and depression of O2- production in PMNs following thermal injury and determine the involvement of circulating factors in the development of these alterations. The kinetics of O2- production and dose responses to formylmethionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA) were depressed in peripheral PMNs following thermal injury in this experimental model. Sera obtained during the period of PMN dysfunction induced depression of O2- production in response to fMLP and elevation of intracellular cAMP in normal PMNs. Pretreatment of normal PMNs with nonsteroidal anti-inflammatory drugs (NSAID; indomethacin or piroxicam) inhibited the elevation of intracellular cAMP mediated by sera from the injured animals but had no effect on the depression of O2- production observed under similar conditions. Treatment of PMNs from injured animals with NSAID under conditions known to reduce the cAMP content of the cells and correct the bactericidal defect did not normalize O2- production. Studies utilizing sera from two thermally injured patients confirmed findings in the guinea pig model of serum-mediated elevation of intracellular cAMP and depression of O2- production in normal PMNs and effects observed with NSAID. These results suggest that circulating factors contribute to the elevation of intracellular cAMP and depression of O2- production in PMNs following thermal injury. Whereas the increase in intracellular cAMP may be involved in the depression of O2- production, our results suggest that there is not a direct link between these alterations.
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PMID:Circulating factors contribute to elevation of intracellular cyclic-3',5'-adenosine monophosphate and depression of superoxide anion production in polymorphonuclear leukocytes following thermal injury. 132 42


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