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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The origin and the physiological role of an endogenous digitalis-like substance were investigated by measuring both the digoxin-like substance by a digoxin radioimmunoassay (RIA) and the inhibitory activity on the ouabain sensitive Na+,K+-ATPase in rats. The digitalis-like substance was in high concentration in the pituitary, and in decreasing concentration in the hypothalamus, adrenal and the other organs as measured by RIA using an antibody raised from a goat. However, the adrenal showed the highest content of digitalis-like substance as measured by the antibody raised from a rabbit. The plasma level markedly decreased during a 2-week sodium-loading, and the adrenal content decreased markedly on hypophysectomy as measured with the rabbit-antibody. Therefore, the substance measured with the rabbit-antibody must be one of ACTH-dependent adrenal steroids. The inhibitory activity on the Na+,K+-ATPase was high in the pituitary gland, and was decreased in order of the adrenal, hypothalamus and other organs. The 2-week sodium-loading increased both the content in the pituitary gland and the output in the urine, and decreased the hypothalamic content. Immunohistochemical staining of the hypothalamus with the antibody revealed that the immunoreactivity is restricted to the neurons of the paraventricular nucleus, supraoptic nucleus, magnocellular accessory nuclei and extended their fibers reaching to the inner layer of the median eminence. To determine the role of the substance in the brain, the crude extract dissolved in artificial cerebrospinal fluid was injected into the lateral ventricle; vasopressor responses, tachycardia and hyperactivity of the splanchnic nerve lasting for more than 30 min were recorded, which resembled the responses to ouabain injected similarly.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence for a digitalis-like substance in the hypothalamopituitary axis in rats: implications in the central cardiovascular regulation associated with an excess intake of sodium. 282 5

The mechanism of glucocorticoid-induced hypertension is not clarified. Recent data suggest an alteration of active electrolyte transport systems by glucocorticoids. We therefore studied the activities of the Na-K pump by measuring the Na-K-ATPase activity in erythrocyte ghosts and the ouabain-sensitive uptake of rubidium in erythrocytes of patients with Cushing's syndrome and of patients with exogenous glucocorticoid excess after treatment with fluocortolone or ACTH. Na-K-ATPase activity was significantly increased in patients with Cushing's syndrome and in patients treated with ACTH compared to the controls. Similarly, total uptake of 86Rb and the ouabain-sensitive uptake in erythrocytes were found to be above the control range both in patients with Cushing's syndrome and in patients treated with fluocortolone. There was no difference in furosemide-sensitive uptake of 86Rb. The results demonstrate an increased maximal activity of the Na-K pump in patients with glucocorticoid excess.
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PMID:Na-K pump activity in erythrocytes of patients with endogenous and exogenous glucocorticoid excess. 299 69

In the rats treated with ACTH or hydrocortisone for 14 days the catalepsy induced by morphine was almost completely inhibited, while the haloperidol induced catalepsy remained unchanged. The morphine induced hypermotility was altered neither by prolonged treatment with ACTH nor by an acute glucocorticoid administration. Inhibition of Na/K ATPase by ouabain led to an increase of striatal acetylcholine (Ach) release, which was enhanced by Met-enkephalin. This effect of the opioid peptide was not demonstrable in the striata of ACTH or hydrocortisone pretreated rats. It is concluded that glucocorticoids are regulatory factors of the striatal opiate neurotransmission possibly via altered receptorial mechanisms.
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PMID:Catalepsy, hypermotility, increase of striatal acetylcholine release induced by morphine and Met-enkephalin as affected by prolonged hydrocortisone and ACTH treatment. 299 39

The effect of corticotropin (ACTH1-39), synacthen (ACTH1-24) and hydrocortisone-hemisuccinate on the activity of Ca-ATPase of skeletal muscle sarcoplasmic reticulum (SR) and calcium (Ca) accumulation in SR vesicles has been studied. It has been shown that ACTH1-39 (I U per 100 g body weight) increased the activity of Ca-ATPase in skeletal muscle SR of rats, while hydrocortisone (5 mg per 100 g body weight) did not change the activity of Ca-ATPase in skeletal muscle SR. However, both hormones increase the total activity of ATPase. ACTH1-39 and ACTH1-24 (0.05-0.0005 U/ml) and hydrocortisone (2.8 X 10(-7)-2.8 X 10(-9) mol/l) increased in vitro Ca-ATPase isolated from rabbit skeletal muscle SR and accumulation of Ca is SR vesicles. At the same time, hydrocortisone reduced calcium/phosphorus ratio, while ACTH1-39 and ACTH1-24 increased it, i.e. hydrocortisone facilitated Ca accumulation in SR requiring more ATP energy, whereas ACTH facilitated Ca accumulation in SR requiring less ATP energy.
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PMID:[Effect of corticotropin and hydrocortisone on the Ca2+-ATPase activity of skeletal muscle sarcoplasmic reticulum]. 304 Jan 51

Chlorpromazine (3 x 10(-4)M) prevents the stimulation of adenyl cyclase activity in thyroid membranes produced by thyrotropin and prostaglandin, ACTH stimulation of adenyl cyclase in adrenal tissue, and glucagon- and epinephrine-stimulation of adenyl cyclase activity in liver. Baseline activity is unaffected. Parathyroid hormone stimulation of kidney preparations was not inhibited under these conditions. At chlorpromazine concentrations >3 x 10(-4)M F(-)-stimulated cyclase activity of thyroid and adrenal tissue was increased. Other phenothiazines, trifluoperazine, and prochlorperazine, have similar effects on thyrotropin and F(-)-stimulated cyclase activity of thyroid. Na(+)- K(+)-dependent ATPase of thyroid is also inhibited by chlorpromazine. Since thymol causes a similar dissociation of hormone- and F(-)-stimulated adenyl cyclase, it is concluded that the surface properties of these agents best account for their effects on adenyl cyclase.
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PMID:Inhibition of hormone-sensitive adenyl cyclase by phenothiazines. 431

Endogenous substances that modulate the activity of (Na+ + K+)-ATPase through interaction at the cardiac glycoside site have been postulated. Reports of digitalis-like biological and immunological activity exhibited by certain ACTH/MSH peptides and 14-OH steroids make these compounds potential candidates as endogenous digitalis-like factors. We tested several ACTH/MSH peptides and 14 alpha-OH steroids in four in vitro assays and detected no significant cardiac glycoside-like activity. On the other hand, chlormadinone acetate, a progesterone derivative shown to bind with high affinity to the digitalis receptor, was nearly equipotent to digoxigenin in a [3H]ouabain radioreceptor assay. In a [3H]digoxin radioimmunoassay, however, digoxigenin and digoxin were equipotent but chlormadinone acetate was inactive. A clear dissociation between radioreceptor assay and radioimmunoassay activity was also observed using 15 beta-OH-progesterone. Our findings indicate that (a) ACTH/MSH peptides and 14 alpha-OH steroids are not viable candidates as endogenous digitalis-like factors, (b) digoxin antibodies are not necessarily directed at molecular determinants critical for biological activity, and (c) among the compounds reported to exhibit digitalis-like activity and postulated to share structural features with an endogenous steroidal digitalis-like factor, only chlormadinone acetate and its congeners appear to constitute tenable models.
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PMID:Endogenous digitalis-like factors: in vitro comparison of biological and immunological activities of peptide and steroid candidates. 609 62

The effects of Na+-K+-ATPase inhibition by ouabain and blockage of Ca2+ influx into the cell by verapamil and lanthanum on the response of isolated rat adrenal glomerulosa cells to angiotensin II, ACTH, and K+ were studied. Ouabain significantly increased basal aldosterone output at a concentration of 10(-5) mol/liter, whereas at 10(-3) mol/liter basal secretion was unaffected. Steroidogenic response to angiotensin II was significantly potentiated at concentrations of ouabain of 10(-5) mol/liter, but responses to angiotensin II, ACTH, and K+ were inhibited by 10(-4) and 10(-3) mol/liter of ouabain. The Ca2+ antagonist verapamil (10(-6) to 10(-4) mol/liter) decreased basal aldosterone secretion as well as the response to angiotensin II, ACTH, and K+. The effects of ouabain (10(-5) mol/liter) on basal and stimulated steroidogenesis were abolished by verapamil (10(-4) mol/liter). Lanthanum decreased basal and angiotensin II, ACTH, and K+ induced aldosterone secretion. The effects of ouabain (10(-5) mol/liter) on basal and stimulated aldosterone biosynthesis were blocked by lanthanum. These results suggest that Ca2+ mediates the effects of angiotensin II, ACTH, K+ and Na+-K+-ATPase inhibition on aldosterone biosynthesis. Ca2+ may be the final common intracellular messenger of most aldosterone secretagogues.
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PMID:Role of Ca2+ in response of adrenal glomerulosa cells to angiotensin II, ACTH, K+, and ouabain. 626 6

A higher (Na,K)-ATPase activity was found in rat capsular (zona glomerulosa) than in decapsulated (zona fasciculata) adrenal. No unusual characteristics of this enzyme were found in the simulation with Na+ and K+ and the inhibition with ouabain. Angiotensin II, ACTH and serotonin, all potent stimulators of aldosterone biosynthesis, did not affect the enzyme. In conclusion, the characteristics of rat capsular adrenal (Na,K)-ATPase are identical to the classical enzyme. It is not the direct receptor or effector for stimulators of aldosterone biosynthesis but a supportive role in mediating the regulatory signal cannot be ruled out.
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PMID:Characterization of rat capsular adrenal (zona glomerulosa) (Na,K)-ATPase activity. 627 23

Differential screening of an adrenal cortex cDNA library for corticotropin (ACTH)-inducible genes led to the isolation of a group of cDNAs representing mitochondrial genes that encode subunits of cytochrome oxidase, ATPase, and NADH dehydrogenase. Northern blot analysis of RNA from cells stimulated by ACTH confirmed the induction of these genes by ACTH yet revealed major differences in the relative responses of the respective mRNAs. The levels of mRNAs for cytochrome oxidase subunit I and ATPase increased 2- to 4-fold and for NADH dehydrogenase subunit 3 increased 20-fold, whereas the levels of the mitochondrial 16S rRNA showed no change within 6 h of ACTH stimulation. These effects of ACTH on mitochondrial mRNA levels probably result from both activation of the H2 transcription unit that encodes mitochondrial mRNAs and alteration of mRNA stability. ACTH also increased the activity of cytochrome oxidase after 12 h of stimulation. Examination of the tissue specificity of expression of five mitochondrial genes showed a wide range of RNA levels among 11 tissues but high correlations between individual RNA levels, consistent with a coordinated expression of the mitochondrial genes, although at different levels in each cell type. Proportionately high levels of mitochondrial mRNAs were found in adrenal cortex, probably reflecting a stimulatory effect of ACTH in vivo. Overall, the results indicate that ACTH enhances the energy-producing capacity of adrenocortical cells.
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PMID:Mitochondrial-genome-encoded RNAs: differential regulation by corticotropin in bovine adrenocortical cells. 750 67

We studied the role of sodium ions in mediating basal and stimulated ACTH release from perifused rat anterior pituitary cells by exposing the cells to the sodium channel opener veratridine or the Na+/K(+)-adenosine triphosphatase inhibitor ouabain to increase the intracellular Na+ concentration or, conversely, by omitting Na+ from the perifusion medium or blocking Na+ entry into the cell with tetrodotoxin, a voltage-dependent sodium channel blocker, to decrease the intracellular Na+ concentration. Neither tetrodotoxin nor Na(+)-free medium had a significant effect on 100 nM arginine vasopressin (AVP) or 10 nM ovine corticotropin-releasing hormone (CRH)-induced ACTH secretion. Veratridine increased basal ACTH secretion by 122% (41.3 +/- 2.9 vs. 18.6 +/- 0.4 pg/min; P < 0.001), the initial spike phase of the response to AVP by 65% (0.28 +/- 0.01 vs. 0.17 +/- 0.03 ng/3 min; P < 0.005), the subsequent sustained phase to AVP by 129% (0.16 +/- 0.01 vs. 0.07 +/- 0.01 ng/7 min; P < 0.005), and the total response to CRH by 70% (0.39 +/- 0.01 vs. 0.23 +/- 0.04 ng/10 min; P < 0.05). Ouabain increased basal ACTH secretion by 39% (45.7 +/- 2.8 vs. 32.9 +/- 2.1 pg/min; P < 0.05), the initial spike phase of the response to AVP by 88% (0.32 +/- 0.02 vs. 0.17 +/- 0.01 ng/3 min; P < 0.005), the sustained phase response to AVP by 67% (0.10 +/- 0.01 vs. 0.06 +/- 0.01 ng/7 min; P < 0.05), and the total integrated response to CRH by 49% (0.88 +/- 0.09 vs. 0.59 +/- 0.03 ng/10 min; P < 0.05). However, the effects of both veratridine and ouabain on basal ACTH secretion were significantly attenuated in Ca(2+)-free EGTA-containing medium, suggesting that this effect was indirect, due to membrane depolarization and consequent influx of extracellular Ca2+. Dexamethasone (100 nM) had no effect on the ACTH response to either veratridine or ouabain. We conclude that changes in the intracellular Na+ concentration and sodium channel activity are not directly involved in AVP- or CRH-induced ACTH secretion.
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PMID:The role of sodium in mediating adrenocorticotropin secretion by perifused rat anterior pituitary cells. 778 18


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