Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A procedure for isolating a suspension of tubules derived from the rabbit medullary thick ascending limb is described. The purity of the preparation was assessed by microscopy and enzyme assays and the viability of the preparation was assessed by measuring oxygen consumption. Microscopy revealed that the suspension contains 95% thick ascending limbs and that the isolation procedure preserves the structure of the epithelium except for the loss of the basement membrane. The preparation had a high activity of calcitonin-sensitive adenylate cyclase, a marker enzyme for the medullary thick ascending limb. Control oxygen consumption was considerably higher than that reported for proximal tubules in the literature, and nystatin or carbonyl cyanide p-trifluoromethoxyphenylhydrazone addition produced a more than 100% increase in oxygen consumption. Furosemide inhibited the oxygen consumption by 43% and ouabain inhibited it by 42%. Furosemide inhibited sodium chloride entry without directly affecting the Na-K-ATPase or cellular metabolism. Chloride removal depressed oxygen consumption to the same extent as furosemide, but some of this action was through direct inhibition of cellular metabolism.
 ...
PMID:Suspension of medullary thick ascending limb tubules from the rabbit kidney. 609 84

The effect of calcitonin (CT) on calcium content and enzyme activity in the hepatic mitochondria of intact rats was investigated. A single subcutaneous administration of CT (80 MRC mU/100 g BW) produced a significant increase in the content of calcium, the activity of pyruvate carboxylase, succinate dehydrogenase and ATPase 15 min after the hormone treatment. The significant increases in calcium content and pyruvate carboxylase activity were also observed 30 min after CT administration, while succinate dehydrogenase and ATPase activity began to decrease. A physiological dose of CT (20 MRC mU/100 g BW) caused a marked increase in calcium content and pyruvate carboxylase activity but not succinate dehydrogenase of ATPase-activity. The removal of calcium by 10 mM EGTA washing of the mitochondria produced a remarkable reduction in pyruvate carboxylase activity increased by CT administration. The addition of calcium ion of 2.5 x 10(-2) - 2.5 x 10(1) nmoles Ca2+ per mg mitochondrial protein produced a marked increase in pyruvate carboxylase activity. The present results suggest that calcium taken up by the hepatic mitochondria after CT administration activates pyruvate carboxylase.
 ...
PMID:Calcitonin increases pyruvate carboxylase activity in hepatic mitochondria of rats. 621 4

The change of subcellular phosphorus content in the liver was investigated after a single sc administration of synthetic [Asu1,7] eel calcitonin (CT) to fed rats. Administration of CT (80 MRC mU/100 g body weight) produced a significant increase in phosphorus content in the mitochondrial fraction, while this increase was not observed in fractions containing plasma membrane, nuclei, microsomes and cytosol. A significant increase in the mitochondrial phosphorus content was observed even at the lowest dose of CT (40 MRC mU/100 g body weight). A single ip administration of 2,4-dinitrophenol (0.1 mg/100 g body weight), an inhibitor of oxidative phosphorylation, did not prevent significant increases in phosphorus contents of the homogenate and the mitochondria caused by administration of CT (80 MRC mU/100 g body weight), although the drug markedly inhibited ATPase activity in the mitochondria. Administration of CT did not produce a significant alteration in the mictochondrial ATPase activity. These results suggest that phosphorus taken up by the liver cells after CT administration is largely located in the mitochondria, and that this increase is not related to oxidative phosphorylation. Presumably the hepatic mitochondria play a role in the storage of intracellular phosphorus increased by CT.
 ...
PMID:Synthetic [Asu1,7] eel calcitonin increases phosphorus content in the hepatic mitochondria of rats. 622 93

Time- and dose-dependent changes in intracellular enzyme activities in kidney and bone from rats injected with calcitonin have been assessed by quantitative cytochemistry. The doses of salmon calcitonin given were similar to those suggested in the Pharmacopoeial rat hypocalcaemia bioassay (1-50 mIU/50 g body weight). The highest doses produced 30% inhibition of alkaline phosphatase activity, maximal within 20 min after injection, in cells of renal proximal tubules and a stimulation of calcium-dependent adenosine triphosphatase activity in kidney cortical and outer medullary cells. Alkaline phosphatase activity in the periosteal bone cells was markedly inhibited at the lowest doses. When doses of human and porcine calcitonins were given which would be equipotent with that of salmon calcitonin in the rat hypocalcaemia bioassay, the effect of the non-mammalian peptide on renal alkaline phosphatase activity was relatively greater than that of the mammalian peptides. Oxidized human calcitonin did not inhibit renal alkaline phosphatase activity even when an amount equivalent to 10 times the highest dose of the unmodified peptide was injected.
 ...
PMID:Quantitative cytochemical responses to exogenously administered calcitonins in rat kidney and bone cells. 622 49

A homogeneous population of single cells from the thick ascending limb of Henle's loop (TALH) has been isolated from the rabbit kidney medulla. A total medullary cell suspension was prepared by a series of collagenase, hyaluronidase, and trypsin digestions and separated on a Ficoll gradient (2.6-30.7% wt/wt). Morphologically, the cells isolated from the TALH were homogeneous and showed polarity within their plasma membrane structure, with a few blunt microvilli on their apical surface and deep infoldings of the basal-lateral membrane. Biochemically, the TALH cells were highly enriched in calcitonin-sensitive adenylate cyclase and Na, K-ATPase. Alkaline phosphatase and arginine vasopressin-sensitive adenylate cyclase, highly concentrated in proximal tubule and collecting duct, were present only in low concentrations in the TALH cells. Additionally, furosemide, a diuretic inhibiting sodium chloride transport in the TALH in vivo, inhibited oxygen consumption of the TALH cells in a dose-dependent manner. The TALH cells were viable, as judged by morphological appearance, trypan blue exclusion, the response of oxygen consumption to 2,4-dinitrophenol, succinate and ouabain, and the cellular Na, K and ATP levels.
 ...
PMID:Separation of renal medullary cells: isolation of cells from the thick ascending limb of Henle's loop. 625 27

Basal-lateral membranes were separated in a self-orienting Percoll (modified colloidal silica) gradient from a heavy microsomal membrane fraction by centrifugation at 48,000g for 0.5 h. The (Na+--K+)-ATPase activity as a marker enzyme for the basal-lateral plasma membrane was 20-fold enriched by this procedure. The adenylate-cyclase activity measured in the basal-lateral membrane fraction was stimulated 6-fold by parathyrin and only up to 1.5-fold by arginine-vasopressin, calcitonin, or isoproterenol. The yield of basal-lateral plasma membranes was 5 to 10 percent of the amount initially present in the homogenate. The method is also applicable to the pig kidney.
 ...
PMID:A simple isolation method for basal-lateral plasma membranes from rat kidney cortex. 626 Oct 79

The effects of calcitonin (CT), epinephrine and glucagon on the plasma membrane Ca-ATPase activity and the calcium content in the liver were investigated 30 min after a single subcutaneous administration of hormones to rats. Ca-ATPase activity in the plasma membrane fraction was significantly decreased by CT (80 MRC mU/100 g BW), while it was not significantly lowered by insulin (100 mU/100 g BW), epinephrine (100 micrograms/100 g BW), glucagon (50 micrograms/100 g BW), or parathyroid hormone (25 U/100 g BW). The calcium content in the liver was markedly increased by CT, while it was not significantly elevated by epinephrine or glucagon. Meanwhile, the decrease of Ca-ATPase activity in the plasma membrane fraction produced by CT was significantly prevented by simultaneous administration of epinephrine or glucagon, and also the increase in liver calcium was noticeably interfered with. The present results suggests that the action of CT on liver calcium may differ from that of epinephrine or glucagon which causes an increase in cyclic AMP in the liver cells.
 ...
PMID:Comparison of calcitonin, epinephrine and glucagon effects on plasma membrane Ca-ATPase activity and calcium content in liver of rats. 644 62

The kidneys play a vital role in mineral homeostasis. In this review, the handling of calcium and the methods currently applied to measuring its intracellular concentration are discussed. The bulk of calcium absorption proceeds in proximal tubules, with smaller fractions recovered by thick ascending limbs, distal convoluted tubules, and connecting tubules. Hormonally regulated transcellular calcium absorption is essentially limited to distal convoluted and connecting tubules. At physiological concentrations, parathyroid hormone, calcitonin, and vitamin D increase net calcium absorption. Calcium absorption by polarized epithelial cells is a two-step process wherein calcium enters the cell across apical plasma membranes and exits across basolateral membranes. Recent electrophysiological and pharmacological experiments demonstrate that apical entry is mediated by calcium channels, which are modestly calcium selective, sensitive to dihydropyridine-type calcium channel blockers, and exhibit a wide range of single-channel conductances. Cellular calcium efflux is mediated by Ca(2+)-ATPase and by Na+/Ca2+ exchange. Ca(2+)-ATPase activity is highest in segments that exhibit significant rates of active calcium absorption. Multiple plasma membrane Ca(2+)-ATPase isoforms have been found in the kidney. Several renal Na+/Ca2+ exchange isoforms have been identified, and their role in effecting calcium efflux is under investigation.
 ...
PMID:Cellular calcium transport in renal epithelia: measurement, mechanisms, and regulation. 762 90

Ca2+ fluxes were examined in HEK 293 cells stably expressing the rat or porcine calcitonin receptors (CTRs). Calcitonin (CT) rapidly increased cytosolic Ca2+ ([Ca2+]i) concentrations in these cells in a manner which was sustained in the presence of extracellular Ca2+ ([Ca2+]e). In cells pretreated with CT, elevation of the [Ca2+]e concentration resulted in a further increase in [Ca2+]i which was concentration-dependent with respect to both the concentration of CT and the increment of [Ca2+]e. Untransfected cells, cells transfected with vector alone, and CTR-transfected cells not treated with CT, were unresponsive to [Ca2+]e. The microsomal Ca(2+)-ATPase inhibitor thapsigargin was able to mimic both the acute [Ca2+]i fluxes and responsiveness to [Ca2+]e mediated by CT in these cells. The CT-induced responsiveness to [Ca2+]e was neither mimicked by, nor affected by, activators of the cAMP or protein kinase C pathways. Treatment of cells with pertussis toxin influenced neither the primary Ca2+ fluxes in response to CT or thapsigargin nor the agonist-induced [Ca2+]e influx. Nifedipine failed to block responses to either CT or thapsigargin. These results lead to the important conclusion that the CTR participates in receptor-activated Ca2+ inflow, in which depletion of intracellular Ca2+ pools leads secondarily to influx of extracellular Ca2+.
 ...
PMID:Calcium inflow in cells transfected with cloned rat and porcine calcitonin receptors. 769 52

Osteoclasts are derived from hemopoietic precursors in the marrow. Their differentiation pathway is still undefined, but an important role was observed for the marrow microenvironment in the regulation of osteoclastogenesis. Various marrow stromal cell subtypes were used to study their possible role in the formation of osteoclasts from myeloblast (M1) cells. Interactions between M1 cells and the 14F1.1 endothelial-adipocyte stromal cell line were demonstrated in a coculture model. M1 cells attached to the adherent layer of 14F1.1 cells and formed distinct foci reminiscente of "cobblestone areas." Following these interactions, M1 cells developed specific enzymatic activities and became multinucleated. Both mononuclear and multinuclear M1 cells became positive to tartrate-resistant acid phosphatase (TRaP) and ATPase, a feature characteristic of osteoclasts, and were also responsive to calcitonin. Furthermore, they attached to mineralized bone particles and their membrane changed into a ruffled border at the zone of interaction with the bone matrix. We thus demonstrated that marrow endothelial-adipocytes may play a role in regulating the differentiation of myeloblasts into osteoclasts.
 ...
PMID:Myeloblastic cell line expresses osteoclastic properties following coculture with marrow stromal adipocytes. 787 31


<< Previous 1 2 3 4 5 6 7 8 Next >>