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PubMed1990

Inositol uptake in rat aorta.

The purpose of this study was to investigate the mechanism of inositol uptake into rat thoracic aorta. 3H-inositol uptake into deendothelialized aorta was linear for at least 2 h and was composed of both a saturable, Na(+)-dependent, and a nonsaturable, Na(+)-independent component. The Na(+)-dependent component of inositol uptake had a Km of 50 microM and a Vmax of 289 pmol/mg prot/h. Exposure to LiCl, ouabain, or Ca2(+)-free Krebs-Ringer bicarbonate solution inhibited uptake. Metabolic poisoning with dinitrophenol, as well as incubation with phloretin, an inhibitor of carrier-mediated hexose transport, also inhibited uptake. Exposure to norepinephrine decreased inositol uptake, while phorbol myristate acetate was without effect. Isobutylmethylxanthine significantly increased inositol uptake, while the increased uptake due to dibutyryl cyclic AMP and forskolin were not statistically significant. Sodium nitroprusside, an activator of guanylate cyclase, and 8-bromo cyclic GMP, were without effect on uptake, as was methylene blue, an inhibitor of guanylate cyclase. Inositol uptake into the aorta was increased when the endothelium was allowed to remain intact, although this effect was likely due to uptake into both the endothelial and smooth muscle cells. These results suggest that the uptake of inositol into vascular smooth muscle is: (1) dependent upon an inward Na(+)-gradient; (2) carrier mediated, and (3) inhibited by alpha 1 adrenoceptor agonists.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Neuropeptide Y potentiates norepinephrine-stimulated inositol phosphate production in the rat tail artery.

We have recently demonstrated the ability of neuropeptide Y to augment norepinephrine-stimulated contractions of the rat tail artery. In [3H]myo-inositol labeled segments of rat tail artery, addition of a concentration of neuropeptide Y (10(-8) M) known to potentiate contractile responses produced no effect on the basal accumulation of [3H]inositol phosphates. Addition of norepinephrine (10(-7) M), however, resulted in the rapid accumulation of [3H]inositol 1,4,5-trisphosphate to 325 +/- 29% of basal levels within 5 min. This effect of norepinephrine on [3H]inositol 1,4,5-trisphosphate accumulation was mirrored by significant increases (274 +/- 25% of control) in total [3H]inositol phosphates. When neuropeptide Y and norepinephrine were added together, the norepinephrine-stimulated increase in [3H]inositol 1,4,5-trisphosphate was significantly augmented (467 +/- 35% of control) as was the increase measured in total [3H]inositol phosphates (366 +/- 21% of control). We suggest that the ability of neuropeptide Y to augment norepinephrine-induced contraction of the rat tail artery is due, at least in part, to the ability of neuropeptide Y to increase norepinephrine-stimulated phospholipase C activity in vascular smooth muscle and may represent the mechanism of action of this co-neurotransmitter in vivo.

Animals↗
PubMed1989

The effect of elevated glucose levels on myo-inositol metabolism in cultured bovine aortic endothelial cells.

Bovine aorta endothelial cells were used to determine the effect of high ambient glucose concentrations on myo-inositol metabolism. Culturing the cells for a minimum of 1 week in elevated glucose concentrations caused an increase in the intracellular sorbitol content and a decrease in myo-inositol levels. The accumulation of myo-inositol from the medium and incorporation into phospholipids was reduced 25% to 50% in cells grown in the presence of 30 to 50 mmol/L glucose. This effect was not observed following a short-term exposure of the cells to elevated glucose levels. Kinetic analysis of high-affinity myo-inositol uptake showed that the K'm was significantly increased in cells grown in 30 mmol/L glucose compared to those cultured in 5.6 mmol/L glucose. This would suggest that exposing endothelial cells to high ambient glucose levels for a minimum of 1 week leads to a competitive type of inhibition of high-affinity myo-inositol uptake. The changes in myo-inositol metabolism and content and sorbitol levels mediated by glucose exposure were blocked by addition of the aldose reductase inhibitor, sorbinil, to the media, suggesting that these changes are caused by the accumulation of sorbitol by the cells. Exposure of bovine aorta endothelial cells to high ambient levels of glucose leads to accumulation of sorbitol in the cells, which is responsible for alterations in myo-inositol metabolism. These changes could result in alteration of endothelial cell membrane function and contribute to the pathology of diabetes mellitus.

Aldehyde Reductase↗
PubMed1989

Formation of inositol polyphosphates in cultured human sweat duct cells in response to cholinergic stimulation.

Inositol phosphate formation in response to cholinergic stimulation was studied in cultured human sweat duct cells, prelabelled with myo-[2-3H]inositol. Formation of inositol mono-, bis-, tris- and tetrakisphosphates was increased after 15 min stimulation by 30 microM carbachol. Formation of inositol 1,3,4-trisphosphate and inositol tetrakisphosphate was significantly increased within 1 min at carbachol concentrations between 10 microM and 100 microM. No detectable increase in inositol 1,4,5-trisphosphate formation was observed at 15 s or 1 min, but an increase was observed after 15 min at a carbachol concentration of 30-100 microM. The data are consistent with an involvement of inositol polyphosphates in the biphasic response of ion transport, to cholinergic stimulation in these cells (see Pederson, P.S. (1986) 6th Professional Conference "Broken Arrow 1986". Genetic and Eptihelial Dysfunction in Cystic Fibrosis (Riordan, J.R. and Buchwalds, M., eds.), Alan Liss, New York and Pedersen, P.S. (1987) Med. Sci. Res. 15, 769-770) and suggest a different pattern of metabolism from exocrine acinar cells.

Calcium↗
PubMed1993

Protein kinase C down-regulation in astrocytes: differential effects on agonist-stimulated inositol phosphate accumulation.

Prolonged phorbol ester treatment abolished protein kinase C (PKC) activity for over 48 h in cortical astrocyte cultures. Receptor-stimulated inositol phospholipid breakdown in these cultures subsequent to PKC depletion produced either enhanced, depressed or unchanged responses depending upon the agonist used. Noradrenaline-, ATP-, histamine- and glutamate-evoked [3H]-inositol phosphate accumulations were potentiated to varying degrees in PKC-depleted cultures whilst those evoked by carbachol and NaF were reduced and unchanged respectively. Analysis of the individual metabolites of inositol phospholipid metabolism formed in response to noradrenaline in PKC-depleted astrocytes revealed potentiated accumulations of radiolabelled glycerophosphoinositol (GPI), inositol monophosphate (IP1) and inositol bisphosphate (IP2) but not inositol trisphosphate (IP3) when compared to controls. Under the same conditions, accumulations of radiolabelled IP1 and IP2 were reduced and those of GPI and IP3 unchanged in carbachol-treated cultures. These results suggest that astrocyte receptors coupled to inositol phospholipid metabolism are differentially regulated by PKC.

Adenosine Triphosphate↗
PubMed1985

Formation of inositol phosphates and calcium mobilization in Swiss 3T3 cells in response to prostaglandin F2 alpha.

Signal transduction in the mitogenic action of prostaglandin F2 alpha on Swiss 3T3 cells has been studied. Confluent and quiescent Swiss 3T3 cells prelabeled with myo-[2-3H]inositol were stimulated with PGF2 alpha for 15 min at 37 degrees C in the presence of 5 mM LiCl, and the amount of total [3H]inositol phosphates, a sum of inositol tris-, bis-, and mono-phosphates, accumulated in the cells was determined. Addition of PGF2 alpha to the cells at 0.2 to 10 microM induced a 1.7 to 2.4-fold increase in [3H]-inositol phosphates. The accumulation was dose-dependent. Since assay of the agonist-dependent accumulation of inositol phosphates in the presence of LiCl has been used as a sensitive method for identifying those receptors that are coupled to the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns (4,5)P2], these results indicate that PGF2 alpha induces in Swiss 3T3 cells hydrolysis of inositol lipids by a phospholipase C. The receptor-stimulated hydrolysis of PtdIns(4,5)P2 is usually coupled with a rise in cytoplasmic free Ca2+ concentration ([Ca2+]i). The effect of PGF2 alpha on [Ca2+]i was studied in quin-2 loaded Swiss 3T3 cells. On addition of 0.1 microM and 1 microM PGF2 alpha, there was an immediate increase in quin-2 fluorescence by 16 to 19% indicating a 1.5 to 1.8-fold increase in [Ca2+]i. These results therefore indicate that PGF2 alpha at 0.1 to 1 microM induces in Swiss 3T3 cells the hydrolysis of inositol lipids and a rise in [Ca2+]i.

Aminoquinolines↗
PubMed1991

Effect of short- and long-term diabetes on carnitine and myo-inositol in rats.

1. The effect of short- (2 wk) and long-term (20 wk) streptozotocin diabetes was studied on urine, blood, liver, heart, brain, skeletal muscle, pancreas and kidney concentrations of acid-soluble carnitine and free myo-inositol. 2. Short-term diabetic rats excreted significantly higher concentrations of carnitine as well as myoinositol than normal rats. Blood carnitine and myo-inositol were not different between normal and diabetic rats. Diabetes caused a decrease in liver, brain and pancreatic carnitine, but not in heart, skeletal muscle and kidney. Myo-inositol concentration was decreased in liver, heart and kidney but not in brain, pancreas and skeletal muscle. 3. Long-term diabetic rats had higher urinary excretions of both carnitine and myo-inositol. Blood carnitine did not change; however, myo-inositol was higher in diabetic than in normal rats. Diabetes caused a significant increase in liver and a decrease in heart, brain, skeletal muscle and pancreatic content of carnitine; no difference in kidney carnitine was noted. Myo-inositol content was elevated only in liver of diabetic rats. 4. We suggest that carnitine and myo-inositol concentrations are influenced both by short- and long-term diabetes through changes in tissue metabolism.

Acute Disease↗
PubMed1993

Inositol 1,4,5-trisphosphate receptors: immunohistochemical localization to discrete areas of rat central nervous system.

The second messenger inositol 1,4,5-trisphosphate triggers the release of intracellular Ca2+ stores upon binding to the inositol 1,4,5-trisphosphate receptor protein, a calcium channel that has been purified and molecularly cloned. To clarify the roles of inositol 1,4,5-trisphosphate receptor in the central nervous system, we have examined in detail the distribution of inositol 1,4,5-trisphosphate receptors in the rat brain and spinal cord using immunohistochemical methods. Inositol 1,4,5-trisphosphate receptors are present in neuronal cells, fibers and terminals in a wide distribution of areas throughout the central nervous system. These include a number of areas not previously reported, such as the olfactory bulb, thalamic nuclei and dorsal horn of the spinal cord. In addition, we have noted a strikingly high density of inositol 1,4,5-trisphosphate receptors in circumventricular organs and neuroendocrine structures such as the area postrema, choroid plexus, subcommisural organ, pineal gland and pituitary. The distribution of inositol 1,4,5-trisphosphate receptors in discrete structures throughout the central nervous system, including interconnected neuronal systems and neuroendocrine and circumventricular organ structures, presumably reflects the importance of Ca2+ release mediated by the phosphoinositide second messenger system in control of diverse physiological processes.

Animals↗
PubMed1996

A new method to measure cardiac inositol levels in intact animals.

Inositol levels have been studied in cellular cultures and recently by perfusion of isolated hearts. The study was aimed to assess inositol turnover in rabbit hearts from intact animals. Thirty rabbits were injected i.v. three times (every 12 hr) with 25 microCi/kg of myo-3H-inositol. The rabbits 12 hr after the last injection were killed and the hearts perfused according to Langerdorff technique. Systolic and diastolic ventricular pressures (SVP, DVP), dp/dt, and coronary flow (CFl) were measured. The hearts (n = 14) were perfused under aerobic conditions and 16 hearts under ischemic conditions for 30 min. In addition, 5 hearts were perfused under aerobic conditions for 10 min, and 6 hearts were perfused under ischemic conditions for 10 min. Samples of myocardial tissue were taken from both groups at the end of 10-min and 30-min period of perfusion, and cAMP and inositol phosphates were assayed. The hearts subjected to ischaemia showed changes of cAMP and 3H-inositol. The cAMP was higher in the ischaemic (10 min and 30 min) than the control hearts, 0.22 +/- 0.09 and 0.21 +/- 0.08 versus 0.41 +/- 0.12 and 0.49 +/- 0.11 pmol 10(6) cells, respectively (p < .05, p < .001. The inositol trisphosphate was higher in control than ischemic hearts (10 min, 30 min), 0.42 +/- 0.02 and 0.39 +/- 0.01 versus 0.31 +/- 0.01 and 0.23 +/- 0.02 (percent of radioactivity) respectively, p < .001. Our data suggest that 3H-inositol may be studied by i.v. administration to intact animals. The ischemia was performed to verify the validity of this new technique.

Animals↗
PubMed2005

GATA4-mediated cardiac hypertrophy induced by d-myo-inositol 1,4,5-tris-phosphate.

We evaluated the effects of d-myo-inositol 1,4,5-tris-phosphate on cardiac hypertrophy. d-myo-inositol 1,4,5-tris-phosphate augmented cardiac hypertrophy as evidenced by its effects on DNA synthesis, protein synthesis, and expression of immediate-early genes c-myc and c-fos, beta-myosin heavy chain, and alpha-actin. The administration of d-myo-inositol 1,4,5-tris-phosphate increased the expression of nuclear factor of activated T-cells and cardiac-restricted zinc finger transcription factor (GATA4). Real-time quantitative RT-PCR showed that d-myo-inositol 1,4,5-tris-phosphate-induced GATA4 mRNA was significantly enhanced even in the presence of the calcineurin inhibitor, cyclosporine A. The effect of d-myo-inositol 1,4,5-tris-phosphate was blocked after inhibition of inositol-trisphosphate receptors but not after inhibition of c-Raf/mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (ERK) or p38 mitogen-activated protein kinase pathways. The study shows that d-myo-inositol 1,4,5-tris-phosphate-induced cardiac hypertrophy is mediated by GATA4 but independent from the calcineurin pathway.

Animals↗
PubMed2005

Myo-inositol, glucose and zinc concentrations determined in the preconceptional period, during and after pregnancy.

OBJECTIVE: To determine the blood concentrations of myo-inositol, glucose and zinc before, during and after normal pregnancy. STUDY DESIGN: Preconceptionally, at 6, 10, 20, 30 and 37 weeks amenorrhea, and 6 weeks after delivery, blood samples of 18 nulliparae and 19 multiparae were obtained and concentrations of serum inositol and glucose, and red blood cell zinc were determined. The data were analyzed using a linear mixed model. RESULTS: The preconceptional mean (S.E.M.) inositol concentration of 21.7 (1.03) micromol/L was comparable to the concentrations at 6 and 37 weeks amenorrhea, 22.2 (1.03) micromol/L, and 19.9 (1.10) micromol/L, respectively. However, the inositol concentrations at 10 and 20 weeks amenorrhea and post partum were significantly lower than the preconceptional inositol concentration, p<0.05. The preconceptional mean (S.E.M.) glucose concentration of 3.9 (1.03) mmol/L was comparable to the concentration at 6 and 10 weeks amenorrhea, 3.9 (1.04) mmol/L and 3.8 (1.04) mmol/L respectively. Also at 20, 30 and 37 weeks amenorrhea and after delivery the glucose concentration was significantly lower than the preconceptional glucose concentration, p<0.05. Preconceptional red blood cell zinc concentrations were comparable to concentrations at 6, 10 and 20 weeks amenorrhea. At 30 and 37 weeks amenorrhea and post partum the zinc concentrations were significantly higher than in the preconceptional period (p<0.01). CONCLUSION: The concentrations of inositol, glucose and zinc significantly change during pregnancy. However, the preconceptional blood concentrations reflect the concentrations determined in the first pregnancy trimester rather well, which is important information to be used in future studies into the role of inositol, glucose and zinc in reproductive disorders.

Adult↗
PubMed2004

Spina bifida and genetic factors related to myo-inositol, glucose, and zinc.

BACKGROUND: Myo-inositol, glucose and zinc and related genetic factors are suggested to be implicated in the etiology of spina bifida. We investigated the biochemical concentrations of these nutrients and polymorphisms in the myo-inositol transporter SLC5A11, myo-inositol synthase ISYNA1, and zinc transporter SLC39A4 in association with spina bifida risk. METHODS: Seventy-six spina bifida triads only were ascertained. In mothers, fathers, and spina bifida children polymorphisms determined were SLC5A11 (544C > T), ISYNA1 (1029A > G), and SLC39A4 (1069C > T). Serum myo-inositol and glucose, and red blood cell zinc concentrations were determined in mothers and spina bifida children. Transmission disequilibrium tests (TDT) were applied to determine associations between the polymorphisms and spina bifida. Associations between biochemical values and genotypes were studied by one-way analysis of variance (ANOVA). Interactions between alleles, biochemical values, and environmental factors were analyzed by conditional logistic regression. RESULTS: No association between SLC5A11, ISYNA1, and SLC39A4 and spina bifida was shown, chi2SLC5A11=0.016, P=0.90; chi2SYNA1=1.52, P=0.22; chi2SLC39A4=0.016, P=0.90; and degrees of freedom (df)=1. Maternal glucose concentrations were comparable for the SLC5A11 genotypes. Significantly lower myo-inositol concentrations were observed in mothers with SLC5A11 CC-genotype, mean (SD) 14.2 (2.6)micromol/L compared to SLC5A11 TT-genotype, 17.0 (3.4)micromol/L, P <0.05 . No significant associations were observed between ISYNA1 and myo-inositol and glucose, and between SLC39A4 and zinc. A significant interaction was demonstrated between a maternal glucose < 4.5 mmol/L and ISYNA1 1029A > G polymorphism on spina bifida risk. CONCLUSION: The combination of maternal glucose < 4.5 mmol/L and ISYNA1 1029A > G polymorphism protects against spina bifida offspring. Moreover, maternal SLC5A11 544C > T polymorphism contributes to the serum myo-inositol concentration. Larger studies should confirm these findings.

Alcohol Drinking↗
PubMed2003

Maternal myo-inositol, glucose, and zinc status is associated with the risk of offspring with spina bifida.

OBJECTIVE: The purpose of this study was to investigate the maternal and children's myo-inositol, glucose, and zinc status in association with spina bifida risk. STUDY DESIGN: Sixty-three mothers and 70 children with spina bifida and 102 control mothers and 85 control children were investigated. The maternal and child serum myo-inositol, serum glucose, and red blood cell zinc concentrations were measured when the child was between 1 and 3 years old. These data were compared between cases and control subjects. The association with spina bifida was expressed by the ratio of geometric means and by odds ratios and 95% CI for a cutoff value at the extreme 10th percentile of the control group. RESULTS: The geometric mean of the maternal myo-inositol concentration tended to be 5% (95% CI, -1% to 11%) lower in cases. Interestingly, the odds ratio for the extreme low maternal myo-inositol concentration was 2.6 (95% CI, 1.1-6.0). The glucose and zinc concentrations were significantly higher at 7% (95% CI, 4%-10%) and significantly lower at 5% (95% CI, 0%-9%), in case mothers compared with control mothers. The odds ratios (95% CI) for maternal high glucose and low zinc concentrations were 4.6 (2.0-10.5) and 2.9 (1.2-7.0), respectively. The geometric mean of the myo-inositol concentration tended to be 7% (95% CI, 0%-14%) lower in children with spina bifida; the glucose and zinc concentrations were comparable. CONCLUSION: Maternal myo-inositol, glucose, and zinc status are associated with the risk of spina bifida in offspring. Furthermore, the myo-inositol status of the child seems to contribute to this risk as well.

Adult↗
PubMed2001

Reduction in the rate of inositol 1,4,5-trisphosphate synthesis in rat parotid acini by lithium.

Stimulation of muscarinic cholinergic receptors on rat parotid acinar cells causes a rapid production of inositol phosphates, with the key metabolic event being the breakdown of phosphatidylinositol 4,5-bisphosphate into inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and diacylglycerol. Here a high-performance liquid chromatographic technique was used to measure the effects of intracellular lithium ions on the amount of various inositol phosphates produced. When acini were stimulated maximally with acetylcholine (ACh), the sum of all inositol phosphates produced followed a monoexponential function with a production rate constant for Ins(1,4,5)P3 of 0.07 +/- 0.01 solidus/sec. The presence of 23 mM LiCl intracellularly reduced the production rate constant of Ins(1,4,5)P3 induced by ACh to 0.03 +/- 0.01 solidus/sec, resulting in a decrease in the Ins(1,4,5)P3 production as well as in the magnitude of the rise in the intracellular free Ca2+ concentration. The lithium ion (Li+) did not affect the rate of conversion of Ins(1,4,5)P3 to either inositol 1,4-bisphosphate or inositol 1,3,4,5-tetrakisphosphate. The rate of the inositol phosphate production after the addition of the Ca2+ ionophore ionomycin was unaffected by intracellular Li+ (23 mM), which implies that the action of Li+ was at the muscarinic cholinergic receptor, on G-protein or on the interactions between G-proteins and phospholipase C. Thus, in the early events after receptor stimulation with ACh, Li+ causes a reduction in the concentration of the cellular messengers Ins(1,4,5)P3 and Ca2+.

Acetylcholine↗
PubMed1986

Potassium depolarisation markedly enhances muscarinic receptor stimulated inositol tetrakisphosphate accumulation in rat cerebral cortical slices.

Rat cerebral cortical slices labelled with [3H]-inositol were incubated with the muscarinic agonist carbachol in media containing normal 5.9 mM or elevated 24 mM K+ ions. Over the first few minutes both carbachol and elevated K+ stimulated the production of [3H]-inositol phosphates. The very rapid formation of [3H]-inositol tetrakis, tris and bisphosphate was followed by accumulation of [3H]-inositol monophosphate. However, elevated K+ resulted in a relatively larger stimulation of [3H]-inositol bisphosphate than muscarinic receptor stimulation. When carbachol effects were examined in media containing elevated K+, production of [3H]-inositol trisphosphate was apparently additive whereas the mono and bisphosphate displayed somewhat synergistic responses after 1-2 minutes. In contrast, [3H]-inositol tetrakisphosphate production was greatly enhanced and marked synergy was observed between the K+ and carbachol responses. The production of the tetrakisphosphate under these conditions was dependent on extracellular Ca2+ and a stimulatory effect of this divalent ion on the 3-kinase is discussed.

Animals↗
PubMed2003

Myo-inositol restores the inflammation-induced down-regulation of taurine transport by the murine macrophage cell line, RAW 264.7.

The role of myo-inositol in the regulation of taurine transport in activated murine macrophage cell line, RAW 264.7, was studied. Challenge of RAW 264.7 murine macrophages for 24 hr with phorbol ester 12-myristate 13-acetate (PMA) (10 ng/ml), a PKC activator, resulted in a 62% decrease in taurine transport activity. Among the various monosaccharides (1 mM) tested in the presence of PMA, myo-inositol was most effective in restoring the PMA-induced down-regulation of taurine transport in murine macrophages (82% increase compared to the value for cells treated with PMA Alone, p < 0.01). The protective role of myo-inositol against stress-induced down-regulation of taurine transport by macrophages was further investigated in conditions mimicking bacterial infection, inflammation, and immune-suppressed circumstances. A challenge of murine macrophages with lipopolysaccharide (LPS) (0.1 and 10 microg/ml) resulted in a 60% decrease in taurine transport activity compared to the value for untreated control cells (p < 0.01). When cells were co-treated with myo-inositol (100 nM approximately 10 mM) in the presence of LPS for 24 hrs, taurine transport activity increased in a dose-dependent manner compared to the value for cells treated with LPS only. Taurine transport activity in cells treated with LPS (10 microg/ml) plus interferon-gamma (IFN-gamma) (150 unit/ml) for 24 hrs was 13% of the value for untreated control cells (p < 0.01). Again, this inflammation-induced down-regulation of taurine transport activity was completely antagonized with co-administration of 100 nM or higher levels of myo-inositol in the culture medium. Similarly, myo-inositol effectively restored the taurine transport activity suppressed by cyclosporin A (0.5 and 50 nM) in murine macrophages (p < 0.01). From these results, myo-inositol appears to be a common accelerator of taurine transport by murine macrophages in diverse conditions of down-regulated taurine transport.

Animals↗
PubMed2001

Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of Escherichia coli.

Using a combination of high-performance ion chromatography analysis and kinetic studies, the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by the phytate-degrading enzyme P2 of Escherichia coli was established. High-performance ion chromatography revealed that the phytate-degrading enzyme P2 of E. coli degrades myo-inositol hexakisphosphate by stepwise dephosphorylation via D/L-Ins(1,2,3,4,5)P(5), D/L-Ins(2,3,4,5)P(4), D/L-Ins(2,4,5)P(3) or D/L-Ins(1,2,4)P(3), D/L-Ins(1,2)P(2) or Ins(2, 5)P(2) or D/L-Ins(4,5)P(2) to finally Ins(2)P or Ins(5)P. Kinetic parameters for myo-inositol pentakisphosphate hydrolysis by E. coli and wheat phytase, respectively, showed that the myo-inositol pentakisphosphate intermediate produced either by the phytate-degrading enzyme of wheat or E. coli are not identical. The absolute configuration of the myo-inositol pentakisphosphate isomer produced by the E. coli enzyme was determined by taking into consideration that wheat phytase produces predominantly the D-Ins(1, 2,3,5,6)P(5) isomer (Lim, P.E., Tate, M.E., 1973. The phytases: II. Properties of phytase fraction F(1) and F(2) from wheat bran and the myo-inositol phosphates produced by fraction F(2). Biochim. Biophys. Acta 302, 326-328). The data demonstrate that the phytate-degrading enzyme P2 of E. coli dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,3,4,5)P(5), D-Ins(2,3,4,5)P(4), D-Ins(2,4,5)P(3), Ins(2,5)P(2) to finally Ins(2)P (notation 6/1/3/4/5).

6-Phytase↗
PubMed1998

Effect of inositol treatment on the behavior of rhesus monkeys: preliminary results.

1. The effects of inositol (20 g/day, oral) on spatial learning and spontaneous home-cage behavior of four Rhesus monkeys, were studied in a crossover design. 2. Results indicate no marked inositol effect on learning, memory, or behavior. There was a suggestion of an effect of chronic inositol in reducing cage-induced repetitive behavior as indicated by increased switching between modes of behavior, and reduction in length of longest behavioral about. Furthermore inositol may increase time spent in environmentally- rather than self-oriented behavior. 3. Previous behavioral studies of inositol were performed in rats, which maintain low brain inositol levels compared to primates, including humans. The present study demonstrates the feasibility of primate behavioral studies with inositol, and shows the need for longer time experiments and increased variety of behavioral tests.

Animals↗