Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. During aerobic incubation in 5 mM glucose medium, 10(-5) M-DNP reduced the action potential duration and amplitude and the developed tension of guinea-pig ventricular muscle more rapidly and to a greater extent than anoxia.2. The DNP effect on electrical and mechanical activity was even more pronounced following prolonged anoxic incubation. Since the action potential duration and developed tension of anoxic ventricular muscle have previously been shown to be dependent on glycolytic ATP, and since the effects of DNP could not be duplicated with NaCN, it was concluded that DNP was exerting an effect in addition to its uncoupling of oxidative phosphorylation.3. Anoxic muscle was incubated with 10(-4) M-IAA or with 10(-4) M-IAA + 10(-4) M-DNP. The ATP content of IAA-treated muscle was significantly lower than control but in the presence of both IAA and DNP there was a further reduction in ATP and an increased lactate production.4. Sodium azide (10(-2) M), a potent inhibitor of mitochondrial ATPase, did not prevent the reduction of ATP in DNP-treated anoxic muscle.5. Ouabain (10(-7) M) partially prevented the rapid decline of action potential duration and developed tension of DNP-treated anoxic muscle. In addition, the glycoside partially blocked the DNP-induced break-down of ATP and stimulation of lactate production.6. Oligomycin (10 mug/ml.) partially prevented the reduction in action potential duration and developed tension of DNP-treated anoxic muscle.7. It was concluded that DNP induces an ;energy leak' by actively promoting the hydrolysis of an high energy glycolytic intermediate at least one step beyond the sites of ATPase inhibition by ouabain and oligomycin.
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PMID:DNP-induced dissipation of ATP in anoxic ventricular muscle. 426 23

Maintenance of cell calcium homeostasis and transepithelial transport of this cation require its extrusion from the cell against a steep electrochemical gradient. Because it has been proposed that a membrane Ca-ATPase activated by micromolar concentrations of Ca2+ prevailing in the cell participates in these processes, we attempted in this study to determine whether such an enzyme is present in the rabbit nephron. A magnesium-dependent ATPase, maximally activated by Ca2+ (Ca-Mg-ATPase) concentrations between 1.1 and 2.3 microM (apparent Km = 0.3-0.4 microM), was found in all segments of the nephron. Ca-Mg-ATPase (pmol.mm-1.h-1) was highest in the distal convoluted tubule (243) and cortical collecting tubule (208), intermediate in the proximal convoluted tubule (140) and medullary thick ascending limb of Henle's loop (135), and lower in the pars recta (97), cortical thick ascending limb (50), and medullary collecting tubule (51). The enzyme was insensitive to ouabain and vanadate, but was inhibited by ruthenium red in a dose-dependent manner (Ki congruent to 2.10(-6) M). Sodium azide, an inhibitor of mitochondrial ATPase, did not affect Ca-Mg-ATPase, suggesting that the enzyme was located in the plasma membrane. The Ca-Mg-ATPase activity measured in most segments of the rabbit nephron in this study appears sufficient to account in theory for the active component of the unidirectional (lumen-to-bath) calcium flux found in the corresponding region of the nephron with in vitro single tubule microperfusion techniques.
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PMID:High-affinity Ca-Mg-ATPase along the rabbit nephron. 617 29