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.

Vanadium and tungsten derivatives as antidiabetic agents: a review of their toxic effects.

Abstract: Tungstate is an oxyanion that has biological similarities to vanadate. In recent years, a number of studies have shown the antidiabetic effects of oral tungstate in animal models of diabetes. However, because of the tissue accumulation and potential toxicity derived from chronic administration of vanadium and tungsten compounds, the pharmacological use of vanadate or tungstate in the treatment of diabetes is not necessarily exempt from concern. In the context of a potential use in the treatment of human diabetes mellitus, the most relevant toxic effects of vanadium derivatives are reviewed and compared with those reported for tungsten. Hematological and biochemical alterations, loss of body weight, nephrotoxicity, immunotoxicity, reproductive and developmental toxicity, and behavioral toxicity have been reported to occur following exposure to vanadium compounds. Moreover, vanadium also has a mitogenic activity affecting the distribution of chromosomes during mitosis and inducing aneuploidy-related end points. In contrast to vanadate, studies about the toxic effects of tungstate are very scant. Early investigations in cats, rabbits, dogs, mice, and rats showed that tungstate was less toxic than vanadate when given intravenously. Although in vitro investigations showed a direct effect of tungstate on the embryo and fetus of mice at concentrations similar to those causing effects in vivo, information on the potential cellular toxicity of tungstate is particularly scarce. Taking into account the recent interest of tungstate as a new potential oral antidiabetic agent, an exhaustive evaluation of its toxicity in mammals is clearly necessary.

In vitro study of the insulin-mimetic behaviour of vanadium(IV, V) coordination compounds

Abstract: A representative set of vanadium(IV and V) compounds in varying coordination environments has been tested in the concentration range 1 to 10–6 mM, using transformed mice fibroblasts (cell line SV 3T3), with respect to their short-term cell toxicity (up to 36 hours) and their ability to stimulate glucose uptake by cells. These insulin-mimetic tests have also been carried out with non-transformed human fibroblasts (cell line F26). The compounds under investigation comprise established insulin-mimetic species such as vanadate ([H2VO4]–), [VO(acetylacetonate)2], [VO2(dipicolinate)]– and [VO(maltolate)2], and new systems and coordination compounds containing OO, ON, OS, NS and ONS donor atom sets. A vitality test assay, measuring the reduction equivalents released in the mitochondrial respiratory chain by intracellular glucose degradation, is introduced and the results are counter-checked with 3H-labelled glucose. Most compounds are toxic at the 1 mM concentration level, and most compounds are essentially non-toxic and about as effective as or more potent than insulin at concentrations of 0.01 mM and below. VV compounds tend to be less toxic than VIV compounds, and complexes containing thio functional ligands are somewhat more toxic than others. Generally, ON ligation is superior in insulin-mimetic efficacy to OO or O/NS coordination, irrespective of the vanadium oxidation state. There is, however, no striking correlation between the nature of the ligand systems and the insulin-mimetic potency in these cell culture tests, encompassing 41 vanadium compounds, the results on 22 of which are reported in detail here. The syntheses and characteristics of various new compounds are provided together with selected speciation results. The crystal and molecular structures of {[VO(naph-tris)]2} [where naph-tris is the Schiff base formed between o-hydroxynaphthaldehyde and tris(hydroxymethyl)amine] are reported. Electronic supplementary material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00775-001-0311-5

Calcium-induced quiescence in reactivated sea urchin sperm.

Abstract: Sperm flagella of the sea urchin Tripneustes gratilla beat with asymmetrical bending waves after demembranation with Triton X-100 in the presence of EGTA and reactivation at pH 81 with 1 mM ATP in the presence of 2 mM MgSO4 Addition of 01--02 mM free Ca2+ to these reactivated sperm induces 70--95% of them to become quiescent This quiescence can be reversed by reduction of the free Ca2% concentration with EGTA, or by dilution to reduce the MgATP2- concentration below 03 mM The quiescent waveform is characterized by a sharp principal bend of approximately 56 rad in the proximal region of the flagellum, a slight reverse bend in the midregion that averages approximately 03 rad, and a principal bend of approximately 11 rad in the tip The quiescent sperm are highly fragile mechanically, and disruption, including microtubule sliding, occurs spontaneously at a slow rate upon standing or immediately upon gentle agitation Mild digestion by trypsin causes a gradual appearance of normal, symmetrical flagellar beating Addition of increasing concentrations of vanadate to quiescent sperm causes a graded decrease in the proximal bend angle, with 50 micrometers vanadate reducing it to approximately 26 rad In the presence of 01 mM free Ca2% and 10 micrometers vanadate, a characteristic, crescented stationary bend is induced in the demembranated sperm, without intermediate oscillatory beating, by the addition of either 01 or 1 mM ATP In the absence of vanadate, these two concentrations of ATP produce asymmetric beating and quiescence, respectively The results support the hypothesis that quiescence in live sperm is induced by an elevated concentration of intracellular Ca2% In addition, they demonstrate that bending can occur in flagella in which oscillatory beating is inhibited and emphasize the close relationship between asymmetric beating and quiescence