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.

Relationship of Transplasmalemma Redox Activity to Proton and Solute Transport by Roots of Zea mays

Abstract: Transplasmalemma redox activity, monitored in the presence of exogenous ferricyanide stimulates net H+ excretion and inhibits the uptake of K+ and α-aminoisobutyric acid by freshly cut or washed, apical and subapical root segments of corn (Zea mays L. cv “Seneca Chief”). H+ excretion is seen only following a lag of about 5 minutes after ferricyanide addition, even though the reduction of ferricyanide occurs before 5 minutes and continues linearly. Once detected, the enhanced rate of H+ excretion is retarded by the ATPase inhibitors N,N′-dicyclohexylcarbodiimide, diethylstilbestrol, and vanadate. A model is presented in which plasmalemma redox activity in the presence of ferricyanide involves the transport only of electrons across the plasmalemma, resulting in a depolarization of the membrane potential and activation of an H+-ATPase. Such a model implies that this class of redox activity does not provide an additional and independent pathway for H+ transport, but that the activity may be an important regulator of H+ excretion. The 90% inhibition of K+ (86Rb+) uptake within 2 minutes after ferricyanide addition can be contrasted with the 5 to 15% inhibition of uptake of α-aminoisobutyric acid. The possibility exists that a portion of the K+ and most of the α-aminoisobutyric acid uptake inhibitions are related to the ferricyanide-induced depolarization of the membrane potential, but that the redox state of some component of the K+ uptake system may also regulate K+ fluxes.

Comparative Study of the Synthesis and Properties of Vanadate-Exchanged Layered Double Hydroxides

Abstract: The synthesis and characterization of polyoxovanadate-intercalated MgAl hydrotalcite-like layered double hydroxides (LDH) is described. Seven different methods have been used to intercalate the vanadate anion. These include exchange of the initial carbonate or terephthalate anions, as well as reconstruction of the layered structure from the carbonate form previously calcined at 550 o C-the reconstruction being either directly to the vanadate or indirectly via a terephthalate intermediate. Preswelling with glycerol was also used in some cases

Ca2+ efflux mechanisms following depolarization evoked calcium transients in cultured rat sensory neurones.

Abstract: 1. We have used a combination of microfluorimetry and patch-clamp techniques to investigate cytoplasmic Ca2+ ([Ca2+]i) buffering in response to physiological Ca2+ loads in neurones cultured from the dorsal root ganglia of the rat. 2. In cells loaded with Indo-1 AM and using high resistance microelectrodes to initiate and record action potentials, single action potentials were associated with a measurable rise in [Ca2+]i. Short trains of action potentials evoked [Ca2+]i transients with monoexponential recovery rates with time constants of around 5 s. 3. Similar Ca2+ buffering properties were seen in cells perfused with patch-clamp pipettes in the whole-cell recording mode suggesting that the slow (seconds) Ca2+ buffering properties were not seriously perturbed by the recording technique. 4. In cells held under voltage clamp, reversal of the Na(+)-Ca2+ exchanger driving force had a small but significant effect on the rate of Ca2+ removal. 5. Increasing extracellular pH or adding vanadate (200 microM) to the internal solution dramatically slowed the rate of recovery. Addition of calmidazolium to the pipette solution also produced a significant but much less dramatic slowing of Ca2+ efflux. 6. The results demonstrate that the activity of a plasmalemmal Ca(2+)-ATPase is important for the removal of somatic Ca2+ loads of a similar amplitude to those generated by the firing of a few action potentials.