5. Adenosine diphosphate (ADP) was less inhibitory than ATP when it replaced part of the latter; inosine triphosphate had little inhibitory effect. Over a similar range, increasing concentration of uridine triphosphate produced progressively increasing inhibition. 6. No inhibitory action on the magnesiumactivated myofibrillar ATPase could be demonstrated with myokinase preparations. 7. Ethylene...

The effects of neurotoxins on levels of mitochondrially encoded gene transcripts in a dopaminergic neuronal cell line, MN9D, were examined following treatment with 200 microM N-methyl-4-phenylpyridinium (MPP(+)) or 6-hydroxydopamine (6-OHDA). As confirmed by a Northern blot analysis, levels of cytochrome c oxidase subunit 3 (COX III) and ATPase subunit 6 (ATPase 6) transcript were decreased in ...

We used histochemical techniques [assays for adenine triphosphatase (ATPase) and succinate dehydrogenase (SDHase) activity] to identify muscle fiber types in the larynx of Xenopus laewis. Male muscle is made up of one fiber type, medium-sized fibers (-9 e(m2) that stain lightly for acid-stable ATPase and intensely for SDHase activity. In contrast, the female has 3 fiber types: small fibers (-6 ...

Peribacteroid membrane vesicles from pea (Pisum sativum) root nodules were isolated from membrane-enclosed bacteroids by an osmotic shock. The ATPase activity associated with this membrane preparation was characterized, and its electrogenic properties were determined. The pH gradient was measured as a change of the fluorescence intensity of 9-amino-6-chloro-2-methoxyacridine and the membrane po...

The effect of vanadate on the plant plasma membrane ATPase were investigated in plasma membrane fractions derived from corn roots (Zea mays L.) and red beets (Beta vulgaris L.). The K(i) for vanadate inhibition of the plasma membrane ATPase from corn roots and red beets was between 6 and 15 micromolar vanadate. In both membrane fractions, 80% to 90% of the total ATPase was inhibited at vanadate...

Adenosine triphosphatase (ATPase) activity in the rectal papillae of Calliphora has been studied by biochemical and histochemical techniques. The microsomal fraction contained a Mg-activated ATPase with a pH optimum of 8-o. The enzyme was not stimulated by the addition of Na+ plus K+ and was insensitive to ouabain. Histochemical studies using modifications of the Wachstein-Meisel method showed ...

Fluorescent indicators were used to detect stimulus-evoked changes in presynaptic levels of intracellular sodium (Na1) and calcium (Ca1) in granule cell parallel fibers in brain slices from rat cerebellum. Ca, increased during stimulation, and three exponentials were needed to approximate its return to prestimulus levels. Ca, decayed to -10% of peak levels with T 100 ms, to -1% of peak values w...

The transport function of the Na pump (Na,K-ATPase) in cellular ion homeostasis involves both nucleotide binding reactions in the cytoplasm and alternating aqueous exposure of inward- and outward-facing ion binding sites. An osmotically active, nonpenetrating polymer (poly(ethyleneglycol); PEG) and a modifier of the aqueous viscosity (glycerol) were used to probe the overall and partial enzymat...

The striatum is believed to be a crucial brain region associated with drug reward. Adaptive alteration of neurochemistry in this area might be one potential mechanism underlying drug dependence. It has been proposed that the dysfunction of Na+,K+-ATPase function is involved in morphine tolerance and dependence. The present study, therefore, was undertaken to study the adaptation of the striatal...