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 ether, chloroform, and halothane on calcium accumulation and ATPase activity of rat heart microsomes and mitochondria as well as on myofibrillar ATPase activity were investigated. Chloroform and halothane depressed microsomal and mitochondrial calcium uptake and binding in a parallel fashion. Ether decreased microsomal calcium binding and mitochondrial calcium uptake to varying degrees, while mitochondrial calcium binding was slightly enhanced. Whereas ether had no effect, chloroform depressed microsomal and mitochondrial total APTase activities and halothane decreased microsomsl ATPase and slightly stimulated mitochondrial total ATPase activities. Halothane was found to depress myofibrillar Mg2+-ATPase and ether was capable of decreasing myofibrillar Ca2+-ATPase. Chloroform was seen to inhibit both myofibrillar enzymes. These results suggest that the cardiodepressant actions of volatile anesthetic agents may be due to alterations in the calcium accumulating abilities of microsomal and mitochondrial membranes while direct myofibrillar effects may contribute to the depression seen with relatively higher concentrations of anesthetics.
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PMID:Subcellular effects of some anesthetic agents on rat myocardium. 15 65

Ultrastructural morphometric and biochemical studies were conducted on hepatic mitochondria from control rats and rats treated in vivo with arsenate to examine changes in interrelationships between mitochondrial structure and biochemical functions. Morphometric analysis disclosed an over-all 1.2-fold increase in the relative mitochondrial volume density and 1.4-fold increase in the surface density of the inner mitochondrial membrane of arsenate-exposed rats. These structural changes were associated with a 1.5-fold increase in 14C-leucine incorporation into all mitochondrial proteins, which was primarily associated with the acid-insoluble membranous fraction. Mitochondria from arsenate-treated rats showed a marked disruption of normal conformational behavior with depression of nicotinamide adenine dinucleotide (NAD)-linked substrate oxidation and a resulting in vivo increase in the mitochondrial [NAD] to [NADH] ratio. Observed changes in mitochondrial membranes from arsenate exposure also resulted in 1.5- to 2-fold increases in the specific activities of the membrane marker enzymes monoamine oxidase, cytochrome oxidase, and Mg2+-ATPase. Activity of malate dehydrogenase, which is localized in the mitochondrial matrix, was unchanged. The results of this study demonstrate a positive quantitative in vivo correlation between mitochondrial structure and function and indicate a marked dependency upon membrane integrity for normal maintenance of the specific biologic activities performed by this organelle in vivo.
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PMID:Studies of hepatic mitochondrial structure and function: morphometric and biochemical evaluation of in vivo perturbation by arsenate. 49 44

Monoclonal antibodies against gizzard smooth muscle myosin were generated and characterized. One of these antibodies, designated MM-2, recognized the 17-kDa light chain and modulated the ATPase activities and hydrodynamic properties of smooth muscle myosin. Rotary shadowing electron microscopy showed that MM-2 binds 51 (+/- 25) A from the head-rod junction. The depression of Ca2+- and Mg2+-ATPase activities of myosin and Ca2+-ATPase activity of heavy meromyosin at low KCl concentration were abolished by MM-2. Viscosity measurement indicated that MM-2 inhibits the transition of 6 S myosin to 10 S myosin. While the rate of the production of subfragment-1 by papain proteolysis of 6 S myosin was inhibited by MM-2, the rate of proteolysis of the heavy chain of 10 S myosin was enhanced by MM-2 and reached the same rate as that of 6 S myosin plus MM-2. These results suggest that MM-2 inhibits the formation of 10 S myosin by binding to the 17-kDa light chain which is localized at the head-neck region of the myosin molecule. MM-2 increased the Vmax of actin-activated Mg2+-ATPase activities of both dephosphorylated myosin and dephosphorylated heavy meromyosin about 10- and 20-fold, respectively. MM-2 also activated the actin-activated Mg2+-ATPase activity of phosphorylated myosin at a low MgCl2 concentration and thus abolished the Mg2+-dependence of acto phosphorylated myosin ATPase activity. These results suggest that MM-2 inhibits the formation of 10 S myosin, and this results in the activation of actin-activated Mg2+-ATPase activity even in the absence of phosphorylation.
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PMID:Inhibition of conformational change in smooth muscle myosin by a monoclonal antibody against the 17-kDa light chain. 246 45

Sarcoplasmic reticulum (SR) Ca2+ uptake and Ca2+-Mg2+-ATPase activity were examined in muscle homogenates and the purified SR fraction of the superficial and deep fibers of the gastrocnemius and vastus muscles of the rat after treadmill runs of 20 or 45 min or to exhaustion (avg time to exhaustion 140 min). Vesicle intactness and cross-contamination of isolated SR were estimated using a calcium ionophore and mitochondrial and sarcolemmal marker enzymes, respectively. Present findings confirm previously reported fiber-type specific depression in the initial rate and maximum capacity of Ca2+ uptake and altered ATPase activity after exercise. Depression of the Ca2+-stimulated ATPase activity of the enzyme was evident after greater than or equal to 20 min of exercise in SR isolated from the deep fibers of these muscles. The lowered ATPase activity was followed by a depression in the initial rate of Ca2+ uptake in both muscle homogenates and isolated SR fractions after greater than or equal to 45 min of exercise. Maximum Ca2+ uptake capacity was lower in isolated SR only after exhaustive exercise. Ca2+ uptake and Ca2+-sensitive ATPase activity were not affected at any duration of exercise in SR isolated from superficial fibers of these muscles; however, the Mg2+-dependent ATPase activity was increased after 45 min and exhaustive exercise bouts. The alterations in SR function could not be attributed to disrupted vesicles or differential contamination in the SR from exercise groups and were reinforced by similar changes in Ca2+ uptake in crude muscle homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of exercise of varying duration on sarcoplasmic reticulum function. 252 76

This study examined the possibility that the postischemic mechanical depression observed in the "stunned" myocardium is a result of an alteration in the control of intracellular calcium. Regional myocardial stunning was produced in five open-chest dogs by eight to twelve 5-minute occlusions of the left anterior descending coronary artery, alternated with 10-minute reflow periods and followed by a final 60-minute period of reperfusion. Systolic segment shortening in the postischemic zone, measured by sonomicrometry, fell from 14.9% at baseline to -1.1% at the end of reperfusion. Sarcoplasmic reticulum isolated from stunned myocardium demonstrated a 17% reduction in oxalate-supported 45Ca2+ transport compared with sarcoplasmic reticulum from normal myocardium (0.93 vs. 1.12 mumol Ca2+/mg protein/min, p less than 0.005). There was also a 20% decrease in the maximal activation by Ca2+ of the sarcoplasmic reticulum Ca2+, Mg2+-ATPase (2.46 vs. 1.96 mumol Pi/mg protein/min, p less than 0.005), and a downward shift in the Ca2+-activation curve of the Ca2+, Mg2+-ATPase. These results indicate that myocardial stunning is associated with damage to the calcium-transport system of the sarcoplasmic reticulum. Altered intracellular control may contribute to the inability of the stunned heart to maintain normal mechanical function.
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PMID:Alterations in cardiac sarcoplasmic reticulum calcium transport in the postischemic "stunned" myocardium. 275 55

ATPase and calcium binding activities were studied in sarcolemmal membranes from hearts of male rats fed either a control or 2% cholesterol diet for different time periods. Studies with isolated membrane revealed a significant increase in Na+-K+ ATPase activity, sialic acid content and ATP-independent calcium binding capacity in the presence of 1.25 mM CaCl2 in the 6 week cholesterol fed group. By 12 weeks, Na+-K+ ATPase, Mg2+-ATPase and Ca2+-ATPase activities as well as ATP-independent calcium binding in the presence of 0.05 mM CaCl2 were increased in membranes from cholesterol fed rats. A significant increase (P less than 0.05) in the sarcolemmal cholesterol/phospholipid molar ratio, which is an indicator of a decrease in membrane fluidity, was also noted in the 12 week cholesterol fed group. Concanavalin A, which is believed to decrease membrane fluidity, stimulated both Mg2+ and Ca2+-dependent ATPase activities and increased ATP-independent calcium binding in control sarcolemmal preparations and these changes resembled those observed in the sarcolemma from cholesterol fed rats. Since concanavalin A did not alter the activity of Na+-K+ ATPase, it appears that some of the observed differences in sarcolemmal activities upon cholesterol feeding did not correlate well with changes in membrane order. At 24 weeks, there was a generalized depression in the sarcolemmal ATPase activities of the cholesterol group; both Mg2+ ATPase and Ca2+ ATPase were significantly less than in control.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heart sarcolemmal ATPase and calcium binding activities in rats fed a high cholesterol diet. 299 27

Diabetes was induced in rats by an intravenous injection of streptozotocin (65 mg/kg body wt), and animals were killed 8 wk later. Some animals were maintained in a diabetic state for 6 wk and then given 2 wk of insulin treatment in vivo. Myofibrils were isolated and ATPase activities measured. Mg2+-ATPase and Ca2+-stimulated ATPase activities were depressed in diabetic rat hearts in comparison to control; insulin treatment normalized these activities. The depression in myofibrillar ATPases was of gradual onset as no changes were detected 2 wk after inducing diabetes. Treatment of diabetic animals with thyroid hormone did not restore changes in myofibrillar ATPase activities. Marker enzyme activities did not reveal any detectable contamination by cardiac membranes. Mg2+-ATPase activity of myofibrillar preparations from control and diabetic hearts responded differently to N-ethylmaleimide modification. Furthermore, myofibrillar sulfhydryl reactivity to 5,5'-dithiobis(2-nitrobenzoic acid) was significantly depressed in diabetic preparations in comparison to control and insulin-treated diabetic animals. These results suggest that the defect in myofibrillar ATPase activities in chronic diabetes may be due to some modification of sulfhydryl groups.
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PMID:Mechanisms of the defect in cardiac myofibrillar function during diabetes. 315 18

The in vitro effects of propranolol, a commonly used beta-adrenergic blocker, on the membrane structure and function of rat heart mitochondria were investigated. It was found that the respiratory control and oxidative phosphorylation of the isolated mitochondria decreased concomitantly when the drug was added to the assay medium. At the concentration higher than 1.0 X 10(-4) M, propranolol significantly inhibited the State 3 respiration but had little effect on the State 4 respiration of the mitochondria. On the other hand, the drug exhibited noncompetitive inhibitions toward the Mg2+-ATPase activity of submitochondrial particles and purified enzyme preparations at the concentrations ranging from 3.0 X 10(-4) to 1.5 X 10(-3) M. The inhibitory constants of propranolol toward the enzyme activity in submitochondrial particles and in the purified preparation were estimated to be 6.7 X 10(-4) and 1.4 X 10(-3) M, respectively. However, the drug did not show significant effect on the activity of any of the enzyme complexes of the mitochondrial respiratory chain. It is thus concluded that propranolol impairs the mitochondrial respiration and oxidative phosphorylation mainly through its inhibition of the Mg2+-ATPase activity of the mitochondria. This effect of propranolol may explain, at least partly, its depression effects on the cardiac functions of the animal.
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PMID:Inhibition of the mitochondrial Mg2+-ATPase by propranolol. 315 82

Acute intraperitoneal administration of lanthanum chloride to newborn chicks at the single dose of 250 mg/kg body weight inhibits calcium binding to brain synaptosomal membrane. There is also marked depression in the activities of neural Ca2+-ATPase, Mg2+-ATPase, and cholinesterase after acute lanthanum chloride intoxication. The inhibition of these enzymes in relation to depletion of calcium binding to the synaptosomal membrane has been discussed.
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PMID:Neurotoxicity of lanthanum chloride in newborn chicks. 613 Jun 44

Intestinal smooth myosin B was prepared from muscle layers around the lesion in dogs with experimental colonic stenosis and in patients with congenital intestinal obstruction. Mg2+-ATPase activity of the myosin B was compared between the proximal dilated segment and distal segment to obstruction. Experimental colonic stenosis: In early period after surgery, proximal colons showed higher activity of myosin B ATPase than distal colons, decreasing to less than distal colon as time passed. Congenital intestinal obstruction: In three cases, whose atresia might have occurred at earlier period of gestation, proximal bowels showed less activity of myosin B ATPase than distal bowels. However, in two cases, whose atresia might have occurred at later period of gestation, and two cases with intestinal stenosis, proximal bowels indicated higher activity of myosin B ATPase than distal bowels. These data suggested that the contractibility of the proximal intestine was depending on the duration of obstruction, and it was depressed in the former patients and was accelerated in the latter patients. These results suggested that the extensive resection of dilated proximal bowel in the congenital atresia is not always necessary to obtain good postoperative intestinal dynamics at the operation of the atresial lesions which may be induced at later period of gestation. They also suggested that surgery for intestinal obstruction should be performed before the depression of intestinal contractibility to get good bowel function.
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PMID:[Myosin B ATPase activity of the intestinal smooth muscle in intestinal obstruction]. 614 39


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