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)

This study investigates the effects of hypophysectomy and subsequent hormone replacement therapy upon the hormonal and osmoregulatory status of coho salmon, Oncorhynchus kisutch, in 7% seawater (SW) and SW. Following hypophysectomy, coho salmon were injected every 2 days for 8 days with thyroxine, growth hormone, and cortisol, alone or in combinations, and sampled 2 days after the final injection. Increased environmental salinity raises plasma sodium, calcium, and magnesium levels, as well as plasma osmolality. Cortisol is hypercalcemic and thyroxine is hypocalcemic in hypophysectomized salmon, but it is unclear whether these effects are due directly to calcium regulation or are the consequence of general effects on the plasma osmotic/ionic balance. Growth hormone and thyroxine together, but not separately, decrease and increase magnesium levels, at low and high environmental salinities, respectively, indicating a complex endocrine control of plasma magnesium. Gill Na+, K+-ATPase activity in hypophysectomized salmon is stimulated by growth hormone and cortisol, but inhibited by thyroxine and raised environmental salinity. This implies a complex endocrine control and indicates that hormonal support is needed to sustain or raise gill Na+, K+-ATPase activity in seawater. Increased environmental salinity induces elevation of plasma cortisol levels in apparent absence of pituitary control, indicating that the interrenals may respond to changes in external and/or internal environment, either directly or indirectly through extrapituitary hormonal or nervous control. Cortisol is a potent inhibitor of calcitonin secretion, as seen by the large decrease in plasma calcitonin levels in cortisol-treated hypophysectomized fish. The study was carried out at a time when thyroxine plasma levels were low. These basal levels were not affected by hypophysectomy, possibly indicating a basal release of thyroxine from the thyroid without stimulatory support of the pituitary gland.
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PMID:Effects of hypophysectomy and subsequent hormonal replacement therapy on hormonal and osmoregulatory status of coho salmon, Oncorhynchus kisutch. 283 Jan 61

The medullary portion of the thick ascending limb of the loop of Henle (TALH) has one of the highest concentrations of Na+-K+-ATPase found in mammalian tissues, reflecting the importance of this nephron segment in the regulation of extracellular fluid volume, as active sodium transport is driven by Na+-K+-ATPase. We have isolated cells derived primarily from the TALH of the outer medulla of rabbit kidney and have identified a cytochrome P450-dependent monooxygenase system which metabolizes arachidonic acid to two biologically active oxygenated peaks, each containing two or more products. One of the peaks potently inhibits cardiac Na+-K+-ATPase and the other relaxes blood vessels. We report that formation of these oxygenated arachidonate metabolites is stimulated by arginine vasopressin and salmon calcitonin. In TALH cells obtained from rabbits made hypertensive by aortic constriction there was a selective increase in P1 and P2 formation compared to other renomedullary cells.
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PMID:Arachidonic acid metabolites and blood pressure control. 284 19

The function of the nephron, the anatomical unit of the kidney, is segmented; at least 12 segments have been identified that differ in their morphology, transport properties and hormonal responsiveness. The medullary portion of the thick ascending limb of the loop of Henle (mTALH) has one of the highest concentrations of (Na+ + K+)ATPase found in mammalian tissues, reflecting the importance of this nephron segment in the regulation of extracellular fluid volume, as active sodium transport is driven by (Na+ + K+)ATPase. Here, in cells derived primarily from the mTALH of the outer medulla of rabbit kidney, we have identified a cytochrome P450-dependent monooxygenase system which metabolizes arachidonic acid to two biologically active oxygenated products; one of the products inhibits (Na+ + K+)ATPase and the other relaxes blood vessels. We report that formation of these oxygenated arachidonate metabolites is stimulated by arginine vasopressin (AVP) and salmon calcitonin (SCT).
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PMID:Renal cytochrome P450-related arachidonate metabolite inhibits (Na+ + K+)ATPase. 298 8

The plasma membranes isolated from rat liver bound 125I-labelled ([125I]) synthetic [Asu1,7]eel calcitonin (CT), with increasing concentrations of [125I]CT. This specific binding was completely saturated at a concentration of 0.5 nM CT. A high affinity Ca2+-stimulated, Mg2+-dependent ATPase [(Ca2+-Mg2+)-ATPase] activity in the plasma membranes was significantly decreased by the presence of a very low concentration of CT (7.4 pM), although the hormone did not affect the activity of the plasma membrane 5'-nucleotidase. The concentration of CT needed for maximal inhibition of (Ca2+-Mg2+)-ATPase in the plasma membranes was less than 0.74 nM. The plasma membranes washed with 10(-3)% digitonin did not show an inhibitory effect of CT on (Ca2+-Mg2+)-ATPase activity, while the reagent did not have a significant effect on the enzyme. These results suggest that the inhibition of (Ca2+-Mg2+)-ATPase activity may be part of the mechanism by which CT elevates cytosolic Ca2+ in liver cells.
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PMID:Regulation of (Ca2+-Mg2+)-ATPase activity by calcitonin binding to rat liver plasma membranes. 299 35

Cytochemical methods for the demonstration of p-nitrophenylphosphatase (p-NPPase) at the electron-microscopic level were applied to avian osteoclasts to elucidate some of the functional differences among ruffled border, other membrane systems, and cellular organelles. The localization of p-NPPase activity occurred in mitochondria, in lysosomes, and on the cytoplasmic side of the ruffled-border membrane. Enzymatic activity in the ruffled-border membrane was sensitive to ouabain and was partially dependent on potassium. Thus, Na+,K+-ATPase, the proposed sodium pump, appears to be present in the osteoclast ruffled border. The activity in ruffled border occurred only when osteoclasts were attached to bone. Following calcitonin treatment many osteoclasts were detached from the bone surface and lacked reaction product along the ruffled-border membrane. The lysosomal p-NPPase activity was not sensitive to ouabain and was distinct from that of other lysosomal phosphatases. The p-NPPase activity in mitochondria was not inhibited by ouabain but was sensitive to duramycin. The mitochondrial p-NPPase may, therefore, represent the mitochondrial proton pump.
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PMID:An ultracytochemical investigation of ouabain-sensitive p-nitrophenylphosphatase in chick osteoclasts. 300 20

The medullary portion of the thick ascending limb of the loop of Henle (mTALH) has one of the highest concentrations of Na+K+-ATPase found in mammalian tissues, reflecting the importance of this nephron segment in the regulation of extracellular fluid volume, as active sodium transport is driven by Na+K+-ATPase. We have isolated cells derived primarily from the mTALH of the outer medulla of rabbit kidney and have identified a cytochrome P450-dependent mono-oxygenase system which metabolizes arachidonic acid to two biologically active oxygenated peaks, each containing two or more products. One of the peaks potently inhibits cardiac Na+K+-ATPase and the other relaxes blood vessels. We report that formation of these oxygenated arachidonate metabolites is stimulated by arginine vasopressin (AVP) and salmon calcitonin (SCT). In mTALH cells obtained from rabbits made hypertensive by aortic constriction there was a selective increase in P1 and P2 formation compared to other renomedullary cells.
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PMID:Cytochrome P450-dependent arachidonate metabolism in renomedullary cells: formation of Na+K+-ATPase inhibitor. 302 41

High affinity (Ca2+ + Mg2+)ATPase activity was demonstrated in proximal tubule basolateral membranes (BLM) obtained from canine kidney. The Km of the enzyme for free Ca2+ was 0.12 +/- 0.02 microM, and at 3 microM free Ca2+, the enzyme reached its maximal velocity. To evaluate hormonal regulation of this enzyme, we studied the in vitro effects of several polypeptide hormones on enzyme activity. We measured the effects of insulin and human (h) PTH-(1-34) and their inactive analogs desoctapeptide insulin, bovine (b) PTH-(3-34), and oxidized hPTH-(1-34); insulin-like growth factors (IGFs) I and II; calcitonin; and the common cellular mediator for PTH and calcitonin, cAMP. At 0.1 microM free Ca2+, insulin (25-100 microU/ml) increased (Ca2+ + Mg2+)ATPase activity in a dose-dependent manner by 35-52% (P less than 0.01) and by 8-13% (P less than 0.05 to P less than 0.01) at a 3-microM free Ca2+ concentration; hPTH-(1-34) PTH (10(-9)-10(-7) M) increased the enzyme activity at a free Ca2+ concentration of 0.1 microM by 13-25% (P less than 0.05 to P less than 0.01). IGF-I increased (Ca2+ + Mg2+)ATPase activity by 40% (P less than 0.05) at 0.1 microM free Ca2+ at high peptide concentrations (10 ng/ml). No effect was obtained at 2 ng/ml IGF-I. cAMP (10(-7)-10(-4) M) stimulated enzyme activity by 18-27% (P less than 0.05 to P less than 0.02) at 0.1 microM Ca2+ and by 8-12% (P less than 0.05 to P less than 0.01) at 3 microM Ca2+. The effects of insulin and cAMP on (Ca2+ + Mg2+)ATPase activity were additive. No effect on the enzyme activity was obtained by the inactive analogs desoctapeptide insulin, bPTH-(3-34), and oxidized hPTH-(1-34), or by calcitonin or IGF-II. The data suggest that insulin and PTH have a specific stimulatory effect on (Ca2+ + Mg2+)ATPase activity in canine kidney proximal tubular BLM. While the insulin action is independent of cAMP, a role of cAMP in the regulatory effect of PTH on this enzyme cannot be ruled out. The direct stimulatory effect of insulin and PTH on (Ca2+ + Mg2+)ATPase in canine kidney proximal tubular BLM suggests that these hormones mediate their cellular effects in part by changes in cellular calcium homeostasis.
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PMID:Hormonal regulation of (Ca2+ + Mg2+)ATPase activity in canine renal basolateral membrane. 302 12

Growing rats were treated with daily im doses of salmon calcitonin (sCT) (2, 15 and 100 IU/kg) for various times (1, 4 and 24 weeks). The effects on intracellular enzyme activities in bone and kidney were monitored using quantitative cytochemical methods previously developed for the identification of specific target tissue responses to calcitonins. The basal alkaline phosphatase activities in both kidney and bone were decreased by long-term treatment at all time periods and doses tested. No change was noted in basal Ca ATPase activities in kidney after treatment. The capacity of target tissues in chronically treated and control rats to respond to an acute iv dose of sCT was also compared. Acute provocation tests in treated and control rats showed that the renal alkaline phosphatase response was decreased in the rats receiving long-term treatment. Moreover, the direction of response was reversed in chronically treated rats when bone alkaline phosphatase and renal Ca-dependent ATPase activity was measured after acute provocation with sCT, i.e. bone alkaline phosphatase was stimulated instead of being inhibited and renal Ca ATPase was inhibited instead of being stimulated. The application of quantitative cytochemical techniques has demonstrated intracellular changes in enzyme activities in both kidney and bone. The impaired sCT responsiveness can be detected at shorter times of treatment (1 week) and lower doses (2 IU/kg) than has previously been possible by measurement of indices of mineral metabolism in plasma or urine.
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PMID:Decreased responsiveness to chronic salmon calcitonin treatment in rat kidney and calvaria studied using quantitative enzyme cytochemistry. 315 45

Mastomys is a rodent which has been reported to develop spontaneous antral endocrine tumors with acid hypersecretion and duodenal ulceration. This study documents the establishment of a breeding colony and the characterization of the tumors and their possible secretagogues. Parietal cell secretory characteristics were studied using isolated gastric glands (IGG) of both normal (n = 5) and tumor-bearing animals. Tumors (n = 6) and control gastric tissue samples were examined by light transmission microscopy and immunohistochemistry. Gastrin was measured by radioimmunoassay in both plasma and tissue. IGG were prepared by collagenase dispersion and acid sequestration assessed by [14C]AP accumulation. Secretory mechanisms of this species were identified by establishment of a histamine dose-response curve and use of 8-bromo-cAMP. Receptor and proton pump inhibitions were assessed using cimetidine (10(-5)M) and the H/K ATPase inhibitor omeprazole (10(-5]. Both reduced [14C]AP accumulation significantly (P less than 0.05). 8-Bromo-cAMP and histamine significantly stimulated [14C]AP accumulation (P less than 0.05). Although parietal cells were substantially increased in tumor animals as compared to controls, the physiological parameters of acid secretion appeared normal in both and were comparable to other species which have been studied. Tumors were Grimelius positive and contained diffuse electron-dense granules. Immunohistochemistry was negative for gastrin, bombesin, serotonin, neuron-specific enolase, calcitonin, and pancreatic polypeptide. Tumor histamine-like immunoreactivity was, however, positive. Normal stomach contained 1001 +/- 185 compared to less than 0.5 pmole/g gastrin in tumors. Plasma gastrin was normal in both groups (29 +/- 5) as compared to 26 +/- 8 pmole/liter. This study characterizes a spontaneous gastric endocrine tumor which is associated with apparent parietal cell hyperplasia and reports of increased acid secretion and duodenal ulceration. The observations are consistent with the elaboration by the tumor of a nongastrin acid-trophic secretagogue.
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PMID:Characteristics of the spontaneous gastric endocrine tumor of mastomys. 334 20

Neuropeptide Y (NPY), which co-exists with noradrenaline (NA) in postganglionic sympathetic nerves, was able to potentiate NA-evoked constriction in certain isolated rabbit blood vessels. The phenomenon was observed in the femoral, the gastroepiploic and the pulmonary arteries but not in the femoral or the gastroepiploic veins or in the aorta. Thus, NPY potentiated NA-evoked vasoconstriction predominantly in muscular arteries with alpha-1 adrenoceptors. NPY-related peptides, such as peptide YY and to some extent pancreatic polypeptide shared this ability, whereas calcitonin gene-related peptide or LPLRFamide did not. The mode of action by which NPY potentiates NA-evoked vasoconstriction was analyzed using the femoral artery. Pretreatment of the vessel with cocaine, a blocker of amine re-uptake, or rolipram, an inhibitor of phosphodiesterase, left the potentiation unaffected, whereas Na+ deficiency or ouabain, an inhibitor of Na+/K+-adenosine triphosphatase, abolished this effect of NPY. Nifedipine, a blocker of Ca++ entry, or removal of extracellular Ca++ shortly before the application of NPY had little effect. After prolonged exposure to a Ca++-free medium (with ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid) the maximum response to NA was greatly reduced and the potentiating effect of NPY was abolished. Thus, the potentiation of NA-evoked vasoconstriction by NPY seems to depend upon the presence of Na+ but not upon a Ca++ influx. An intracellular sequestered Ca++ pool appears to play a critical role.
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PMID:Neuropeptide Y potentiates noradrenaline-evoked vasoconstriction: mode of action. 392 74


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