Topic
Vanadate
About: Vanadate is a research topic. Over the lifetime, 4497 publications have been published within this topic receiving 120109 citations. The topic is also known as: vanadate.
Papers published on a yearly basis
Papers
More filters
TL;DR: The results suggest that intracellular cyclic AMP exerts its effects on K+ transport by several mechanisms: an increase in the driving force for K+ efflux due to the depolarization induced by opening of Cl− channels, a stimulation of the basolateral uptake of K+ via the Na+‐K+‐Cl−‐cotransporter, and a decrease of the ratio of basol lateral versus apical K+ conductance leading to an enhanced efflux of K
Abstract: 1. The effect of agonists of the cyclic AMP pathway and of 293B, a chromanole-derived K+ channel blocker, on K+ transport in the rat distal colon was studied by measuring unidirectional fluxes, uptake, and efflux of Rb+ in mucosa-submucosa preparations and by patch-clamp of crypt epithelia from isolated crypts. 2. 293B concentration-dependently inhibited basal and forskolin-stimulated short-circuit current. In isolated crypts 293B blocked a basal K+ conductance but had no effect on cyclic AMP-evoked depolarization induced by the opening of apical Cl- channels. When the effect of cyclic AMP on Cl- conductance was prevented by substituting Cl- with gluconate, an inhibition of total cellular K+ conductance by forskolin and a membrane-permeable cyclic AMP analogue was unmasked. 3. Unidirectional ion flux measurements revealed that 293B suppressed the increase in JRbsm induced by forskolin. This, together with the inhibition of cyclic AMP-induced anion secretion indicates that the drug blocks K+ channels, presumably both in the apical and the basolateral membrane. Forskolin caused not only inhibition of K+ absorption, but also stimulation of K+ secretion. The inhibition was diminished, but not blocked, in the presence of inhibitors of the apical H(+)-K(+)-ATPase, vanadate and ouabain. Forskolin stimulated serosal, bumetanide-sensitive Rb+ uptake, whereas mucosal, ouabain/vanadate-sensitive uptake remained unaffected. 4. Efflux experiments revealed that forskolin caused a redistribution of cellular K+ efflux reducing the ratio of basolateral versus apical Rb+ efflux. 5. These results suggest that intracellular cyclic AMP exerts its effects on K+ transport by several mechanisms: an increase in the driving force for K+ efflux due to the depolarization induced by opening of Cl- channels, a stimulation of the basolateral uptake of K+ via the Na(+)-K(+)-Cl(-)-cotransporter, and a decrease of the ratio of basolateral versus apical K+ conductance leading to an enhanced efflux of K+ into the lumen and a reduced K+ efflux to the serosal compartment.
54 citations
TL;DR: In this article, the influence of cerium nitrate in vanadate solutions on the properties of Ce-V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce−V conversion coating for AZ31nesium alloy.
54 citations
TL;DR: In this article, the dependence of solid state and solution structures on the ring size of the cyclodextrin is discussed and the synthesis potential and transformation reactions found for dioxidovanadium(V) complexes with N-salicylidene hydrazide ligands are reminiscent of what is usually observed for carboxylates.
54 citations
TL;DR: Findings give strong confirmation of the concepts that in intact Pgp both nucleotide sites are active in MgATP hydrolysis, and that they interact strongly.
Abstract: ATPase activity of P-glycoprotein (multidrug-resistance protein) was found to be potently inhibited by beryllium fluoride (BeFx) in combination with MgATP, MgADP, or corresponding Mg-8-azido-nucleotides. Inhibition was due to trapping of nucleoside diphosphate at catalytic sites. Full inhibition was achieved on trapping of 1 mol of nucleotide per mol of Pgp. Reactivation was slow (t(1/2) = 32 min at 37 degrees C), and release of trapped nucleotide correlated with recovery of ATPase. Trapping of 8-azido-ADP followed by UV irradiation yielded permanent inactivation and specific labeling of Pgp in plasma membranes. Both N- and C-terminal nucleotide binding sites were labeled. These findings give strong confirmation of the concepts that in intact Pgp both nucleotide sites are active in MgATP hydrolysis, and that they interact strongly. The characteristics of inhibition by BeFx were similar in general to those seen with vanadate. However, PPi gave strong protection against BeFx inhibition, and in this respect, inhibition by BeFx was clearly different from vanadate inhibition.
54 citations
TL;DR: The results are consistent with the concept of IP3 serving as a second messenger for insulin secretion, as increases in Ca2+ levels in the submicromolar range have been previously shown to induce insulin release in digitonin-permeabilized islets.
Abstract: Glucose-induced insulin secretion is thought to be mediated by submicromolar increases in intracellular Ca2+, although the intracellular processes are not well understood. We have used the previously characterized digitonin-permeabilized insulin-secreting pancreatic islet model to study the role of myo-inositol 1,4,5-trisphosphate (IP3), a putative second messenger for mobilization of intracellular Ca2+. Ca2+ efflux from the endoplasmic reticulum was studied with or without vanadate present to inhibit Ca2+ reuptake. IP3 (10 microM), at a free Ca2+ level of 0.06 microM, increased Ca2+ release by 30% and, when vanadate was present, by 50%. Maximal and half-maximal Ca2+ release was observed at 10 microM- and 2.5 microM-IP3, respectively. IP3 provoked a rapid release that was followed by slow reuptake. Reuptake was diminished in the presence of vanadate. Inositol 1,4-bisphosphate, inositol 1-phosphate and other phosphoinositide metabolites did not have any significant effect. Because increases in Ca2+ levels in the submicromolar range have been previously shown to induce insulin release in digitonin-permeabilized islets, our results are consistent with the concept of IP3 serving as a second messenger for insulin secretion.
54 citations