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PubMed1993

Biochemical changes in malignant hyperthermia susceptible swine: cyclic AMP, inositol phosphates, alpha 1, beta 1- and beta 2-adrenoceptors in skeletal and cardiac muscle.

It has been presumed that alteration in the concentrations of second messengers leads to alterations in the function of the ryanodine receptor. Consequently, we have determined the basal content of cyclic AMP and inositol phosphates in skeletal and cardiac muscle of malignant hyperthermia (MH) susceptible (MHS) and healthy normal control (MHN) swine. Since alpha 1- and beta-adrenoceptors are linked to these second messenger systems, the densities of alpha 1- and beta-adrenoceptors were also determined. In skeletal as well as cardiac muscle, a higher basal concentration of almost all of the inositol phosphates was found. Of all inositol phosphates measured, the presumed second messenger inositol 1,4,5-trisphosphate (1,4,5-IP3) was mostly concentrated in both tissues. Each MHS sample contained more 1,4,5-IP3 than the highest value observed in MHN muscle, indicating that a threshold of 1,4,5-IP3 concentration for determination of MHS or MHN status can be defined. In addition, MHS skeletal muscle contained more cAMP than MHN, whereas there was no difference between MHS and MHN in cardiac muscle. The changes observed in the different inositol phosphate and cAMP contents were not accompanied by an altered alpha 1- or beta-adrenoceptor density in skeletal or cardiac muscle between MHS and MHN. However, the total number of beta-adrenoceptors of MHN and MHS was significantly higher in cardiac (about 80 fmol/mg protein) than skeletal muscles (about 30 fmol/mg protein). The cardiac muscles revealed about 80% beta 1- and beta 2- and 20% beta 2-adrenoceptors, whereas skeletal muscles were characterized by over 95% beta 2-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Chlorpromazine induces accumulation of inositol phosphates in C6 glioma cells.

The capacity to modify the incorporation of [2-3H]myo-inositol into inositides and inositol phosphates was different for three psychotropic cationic amphiphilic drugs. Chlorpromazine, desmethylimipramine and propranolol were able to increase the labeling of inositol-containing lipids, but only chlorpromazine dramatically increased the incorporation into inositol phosphate, -bisphosphate and -trisphosphate. The increase was 10- to 50-fold in 60 min as compared with controls. This effect is not due to stimulation of lipid labeling, because in chase experiments radioactivity in inositol phosphates increased to a greater extent than in their parent lipids. It is possible that the alteration of phosphoinositide catabolism is related to the neuroleptic activity of the drug.

Animals↗
PubMed1988

In vivo electrical stimulation of the sympathetic nerve of the eye increases inositol phosphate production and prostaglandin release in the rabbit iris muscle.

The effects of in vivo electrical stimulation of the sympathetic nerve of the eye on phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis in rabbit iris and release of arachidonate and prostaglandin (PG) E2 into aqueous humor were investigated. myo-[3H]Inositol or [1-14C]arachidonate was injected intracamerally into each eye 3 h before electrical stimulation of one of the sympathetic trunks. Tissue phosphoinositides were determined by TLC, and 3H-labeled inositol phosphates were analyzed by either ion-exchange chromatography or HPLC. The aqueous humor was analyzed for 14C-labeled arachidonate and PGE2 by radiochromatography and for unlabeled PGE2 by radioimmunoassay. The results obtained from this study can be summarized as follows: (a) The rates of in vivo incorporation of myo-[3H]inositol into phosphoinositides and accumulation of 3H-labeled inositol phosphates in the iris muscle increased with time and then leveled off between 3 and 5 h. (b) Distribution of 3H radioactivity in inositol phosphates, as determined by HPLC, showed that of the total radioactivity in inositol phosphates, 53.6% was recovered in myo-inositol 1-phosphate, 36% in myo-inositol bisphosphate, 0.95% in myo-inositol 1,3,4-trisphosphate (1,3,4-IP3), and 2.6% in 1,4,5-IP3. (c) Electrical stimulation of the sympathetic nerve resulted in a significant loss of 3H radioactivity from PIP2 and a concomitant increase of that in IP3, an observation indicating that PIP2 is the physiological substrate for alpha 1-adrenergic receptors in this tissue. (d) Release of IP3 and liberation of arachidonate for PGE2 synthesis are dependent on the duration of stimulation and the intensity (voltage) of stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium in cultured porcine thyroid cells.

The initial signal for thyroid cell proliferation is unknown. This is the first report to show that epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium ([Ca2+]i) in the thyroid gland. In cultured porcine thyroid cells, 10 nM EGF produces a breakdown of phosphatidylinositol and stimulates inositol phosphate production. Ten nM EGF increases [Ca2+]i, measured using fura-2, a fluorescent Ca2+ indicator; the EGF-induced [Ca2+]i response occurs immediately, reaches a maximum within several seconds, and then slowly declines. EGF stimulates production of inositol phosphates, which seem to increase [Ca2+]i. Inositol phosphate production and an increase in [Ca2+]i after EGF-stimulation may function as an initial signal for thyroid cell proliferation.

Animals↗
PubMed1995

Effects of dietary fat supplementation on inositol phosphate release and metabolism in rat left atria.

Eight weeks dietary supplementation with oils enriched in saturated fats, n-6 polyunsaturated fats and n-3 polyunsaturated fats resulted in a reduced inositol phosphate response in isolated rat left atria. Reductions in both basal activity and norepinephrine-stimulated activity were observed. Diets supplemented with n-3 polyunsaturated fats produced a greater decrease in the norepinephrine-stimulated release than the other dietary groups. In addition, supplementation with n-6 polyunsaturated fats resulted in higher levels of the Ca(2+)-releasing compound inositol(1,4,5)trisphosphate while addition of n-3 fats eliminated accumulation of inositol(1, 4)bisphosphate in response to norepinephrine. The reduction in inositol phosphate accumulation observed in all fat-supplemented groups demonstrates the need for caution in choosing relevant control groups in such dietary studies. The specific effects of n-6 and n-3 polyunsaturated fats on individual inositol phosphate isomers demonstrates subtle effects on inositol phosphate metabolism, the significance of which requires further investigation.

Animals↗
PubMed1995

Evidence for the coupling of Gq protein to D1-like dopamine sites in rat striatum: possible role in dopamine-mediated inositol phosphate formation.

The role of G proteins in mediating the coupling of D1 dopamine receptors to inositol phosphate formation was investigated in rat brain striatum. Pertussis toxin-activated ADP-ribosylation ( > or = 95%) did not affect the ability of the D1 agonist SKF38393 to stimulate the generation of inositol phosphates in striatal slices. Stimulation of striatal membranes with dopamine in the presence of [35S]GTP gamma S or [alpha-32P]GTP increased guanine nucleotide binding to G alpha s, G alpha i, and G alpha q in a concentration-dependent fashion. The activation of G alpha s and G alpha q was mimicked by the D1 agonist SKF38393 and blocked by the D1 antagonist SCH23390. In contrast, the D2/3 dopamine receptor agonist quinpirole stimulated guanine nucleotide binding to G alpha i, and dopamine-stimulated activation of G alpha i was attenuated by the D2 antagonist I-sulpiride. Furthermore, antisera directed against G alpha s or G alpha q but not G alpha i, G alpha o, or G alpha z precipitated specific D1-like binding sites labeled with [3H]SCH23390. The D1-like receptors that coprecipitated with G alpha s-but not with G alpha q can be recognized by a specific D1 dopamine receptor antibody. The data provide evidence to suggest that in addition to coupling to Gs/adenylyl cyclase, D1-like dopamine sites that couple to Gq may mediate dopamine-stimulated formation of inositol phosphates in the rat striatum.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1987

Receptor coupled events in bradykinin action: rapid production of inositol phosphates and regulation of cytosolic free Ca2+ in a neural cell line.

The addition of bradykinin to NG115-401L cells grown on coverslips results in the generation of rapid transient increases in intracellular [Ca2+] and inositol phosphates. Changes in intracellular Ca2+, measured using the fluorescent indicator dye Fura-2, show two components; an initial rapid peak in [Ca2+]i which is essentially independent of extracellular Ca2+, and a sustained plateau dependent on the presence of extracellular Ca2+. Analysis of bradykinin stimulated production of [3H]inositol phosphates, by h.p.l.c., shows a rapid biphasic production of inositol 1,4,5-trisphosphate, inositol tetrakisphosphate and inositol bisphosphates, followed by a sustained rise in inositol 1,3,4-trisphosphate production. Quantitative measurements have indicated the presence of other, more polar, [3H]inositol-labelled metabolites which do not show major changes on bradykinin stimulation. The initial phase of inositol phosphate production parallels the rapid transient increase in intracellular [Ca2+], however, the second phase of inositol phosphate production occurs when intracellular [Ca2+] is declining and implies a complex series of regulatory events following receptor stimulation. Similar time courses of inositol 1,4,5-trisphosphate and Ca2+ signals provides supporting evidence that inositol 1,4,5-trisphosphate is the second messenger coupling bradykinin receptor stimulation to release of Ca2+ from intracellular stores.

Animals↗
PubMed1996

Noradrenaline-induced inositol phosphate formation in rat striatum is mediated by alpha 1A-adrenoceptors.

The aim of this study was to assess the contribution of alpha 1-adrenoceptor subtypes to noradrenaline (NA)-induced inositol phosphate formation in rat striatum. In cross-chopped slices and in the presence of 10 mM LiCl, NA stimulated the accumulation of [3H]inositol phosphates. After 60-min incubation with 100 microM NA, [3H]IP1 was the major product detected (82 +/- 3% of total [3H]inositol phosphates). Best-fit values for the concentration-response curve for NA-induced [3H]IP1 accumulation yielded an EC50 of 9.4 +/- 1.1 microM, maximum effect of 210 +/- 3% of basal, and Hill coefficient (nH) of 1.1 +/- 0.1. Pre-treatment of the slices for 30 min with the alkylating agent chloroethylclonidine (100 microM) failed to decrease significantly the response to 100 microM NA. Inhibition curves for four alpha 1-antagonists, (+)-niguldipine, prazosin, WB-4101 and 5-methylurapidil (5-MU), best-fit to a single-site model with pKi values of 9.4 ((+)-niguldipine), 9.2 (prazosin and WB-4101) and 8.8 (5-MU). The putative alpha 1 D-selective antagonist BMY 7378 reduced the response to NA only partially (30 +/- 3% inhibition at 1 microM: pKi 7.24). NA-induced [3H]IP1 accumulation was significantly reduced (to 20 +/- 9% of controls) by Ca2+ removal and increased as the extracellular Ca2+ concentration was raised from nominally zero (no added Ca2+) to 1 mM Ca2+. NA-induced [3H]IP1 accumulation was reduced by both the non-selective Ca2+ channel blocker Ni2+ (58 +/- 3% inhibition at 2 mM) and nimodipine, an antagonist of L-type voltage-operated Ca2+ channels (77 +/- 4% inhibition at 3 microM). Taken together these results indicate that NA-induced inositol phosphate formation in striatal slices is mediated by activation of alpha 1A-adrenoceptors coupled to Ca2+ entry and Ca2+ activation of phospholipase C.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2000

Coupling of canine serotonin 5-HT(1B) and 5-HT(1D) receptor subtypes to the formation of inositol phosphates by dual interactions with endogenous G(i/o) and recombinant G(alpha15) proteins.

Molecular cloning and expression of canine (ca) serotonin 5-HT(1B) and ca 5-HT(1D) receptor subtypes showed that besides the lower binding affinity of ketanserin for the ca 5-HT(1D) receptor, the ligand binding profiles were similar to their human homologues. Site-directed mutagenesis studies suggest that a Gln(189) residue in the second extracellular loop of the ca 5-HT(1D) receptor may partially account for the lower binding affinity of ketanserin. The coupling of ca 5-HT(1B) and ca 5-HT(1D) receptor subtypes to the phospholipase C pathway was analyzed by measuring stimulation of inositol phosphate formation in COS-7 cells. Zolmitriptan potently stimulated (EC(50) = 4.9 nM) the inositol phosphate formation at ca 5-HT(1D) receptors in a fully pertussis toxin (PTX)-dependent manner, whereas only a weak PTX-resistant inositol phosphate response (26-29% at 10 microM zolmitriptan) could be detected for the ca 5-HT(1B) receptor at a similar expression level. In contrast, both ca 5-HT(1B) and ca 5-HT(1D) receptor subtypes yielded a similar maximal magnitude of inositol phosphate formation (300-340% at 10 microM zolmitriptan) upon co-expression with a mouse (m) G(alpha15) protein. PTX treatment and co-expression with a beta-adrenergic receptor kinase C-terminal polypeptide partially (20-46%) abolished the m G(alpha15) protein-dependent ca 5-HT(1B) and ca 5-HT(1D) receptor-mediated stimulation of inositol phosphate formation. This study suggests both 5-HT receptor subtypes can activate betagamma subunits of endogenous G(i/o) proteins besides their coupling to recombinant m G(alpha15) protein.

Amino Acid Sequence↗
PubMed1992

Pertussis toxin blocks activin A-induced production of inositol phosphates in rat hepatocytes.

The present study was conducted to examine an involvement of G protein in the action of activin A in rat parenchymal liver cells. Activin A induced a dose-dependent increase in inositol phosphates in cells prelabelled with [3H]inositol. The effect of activin A was completely blocked by pretreatment of the cells with pertussis toxin. In contrast, pertussis toxin had little effect on angiotensin II-induced production of inositol phosphates. Both activin A and angiotensin II inhibited glucagon-mediated production of cAMP. Pretreatment of the cells with pertussis toxin blocked the inhibition induced by both activin A and angiotensin II. In permeabilized cells, activin A augmented production of inositol phosphates. Activin-mediated production of inositol trisphosphate was enhanced by GTP-gamma S and was attenuated by GDP-beta S. These results suggest that a pertussis toxin-sensitive G protein(s) may be involved in the action of activin A in hepatocytes.

Activins↗
PubMed1988

Effect of atropine and gammahydroxybutyrate on ischemically induced changes in the level of radioactivity in [3H]inositol phosphates in gerbil brain in vivo.

Brain ischemia in gerbils was induced by ligation of both common carotid arteries for 1 min or 10 min. Sham-operated animals served as controls. Intracerebral injection of [3H]inositol into gerbil brain 16 hr before ischemic insult resulted in equilibration of the label between inositol lipids and water-soluble inositol phosphate. A short ischemic period (1 min) resulted in a statistically significant increase in the radioactivity of inositol triphosphate (IP3) and inositol monophosphate (IP), by about 48% and 79%, respectively, with little change in that of the intermediate inositol biphosphate (IP2), which increased by about 16%. When the ischemic period was prolonged (10 min), an increase in the radioactivity of inositol monophosphate exclusively, by about 84%, was observed. The level of radioactivity in inositol phosphates IP2 and IP3 decreased by about 50%, probably as a consequence of phosphatase activation by the ischemic insult. The agonist of the cholinergic receptor, carbachol, injected intracerebrally (40 micrograms per animal) increased accumulation of radioactivity in all inositol phosphates. The level of radioactivity in IP3, IP2, and IP was elevated by about 40, 23, and 147%, respectively. The muscarinic cholinergic antagonist, atropine, injected intraperitoneally in doses of 100 mg/kg body wt. depressed phosphoinositide metabolism in control animals. The level of radioactivity in water-soluble inositol metabolites in the brain of animals pretreated with atropine was evidently about 32% lower than in untreated animals. Pretreatment with atropine decreased the radioactivity of all inositol phosphates in the brain of animals subjected to 1-min ischemia and the radioactivity of IP in the case of 10-min brain ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

HPLC with inductively coupled plasma optical emission spectrometric detection for the analysis of inositol phosphates.

The use of inductively coupled plasma optimal emission spectroscopy as a detector for the high-performance liquid chromatographic analysis of inositol phosphates is studied. It is found that separation of different inositol phosphates with a mobile phase consisting of tetraethylammonium (0.14%, w/v), methanol (5%, v/v), and formic acid (0.18%, w/v) may be obtained on a PRP-1 column with an analysis time of 18 min. In addition, high specificity and sensitivity of the detection system used permits detection of the inositol phosphates from bi- to hexaphosphate free from interference of other chromatographic peaks, which could be from the sample or mobile phase. Additionally, it is possible to use less sample because of the high sensitivity of the detection system.

Chromatography, High Pressure Liquid↗
PubMed1985

1,2-Diacylglycerol and phorbol ester inhibit agonist-induced formation of inositol phosphates in human platelets: possible implications for negative feedback regulation of inositol phospholipid hydrolysis.

The present study has demonstrated that pretreatment of human platelets with either phorbol ester or 1,2-diacylglycerol inhibits agonist-induced formation of inositol phosphates; this inhibition can be correlated with a decrease in the release of ATP and 5-hydroxytryptamine by thrombin. The mechanism of this action is not known, but a role for protein kinase C is suggested, as both phorbol ester and 1,2-diacylglycerol have in common the ability to activate this enzyme. These results have important implications as a possible negative feedback control over agonist-induced hydrolysis of inositol phospholipids.

Blood Platelets↗
PubMed1986

Angiotensin II and dopamine modulate both cAMP and inositol phosphate productions in anterior pituitary cells. Involvement in prolactin secretion.

Despite their opposite effects on prolactin secretion, both dopamine and angiotensin II inhibit adenylate cyclase activity in homogenates of anterior pituitary cells in primary culture. Dopamine and angiotensin II inhibition of adenylate cyclase was not additive, suggesting that both neurohormones inhibit the adenylate cyclase of the lactotroph cells. Pretreatment with Bordetella pertussis toxin (islet activator protein) completely suppressed the dopamine-induced inhibition of both adenylate cyclase and prolactin secretion. The islet activator protein also reversed the angiotensin II-induced inhibition of the adenylate cyclase activity. In contrast, angiotensin II stimulation of prolactin release was not affected by the toxin. Angiotensin II also induced a dose-dependent stimulation of inositol phosphates (250%) with an EC50 of 0.1 nM, close to that observed for prolactin secretion. Islet activator protein pretreatment did not block the stimulation of inositol phosphate production. Dopamine inhibited the angiotensin II-stimulated prolactin release and the production of inositol phosphates induced by angiotensin II. It is concluded that angiotensin II and dopamine receptors of lactotroph cells are able to modulate both cAMP and inositol phosphate production. The dopamine receptor of lactotrophs appears to be the first example of a receptor which is negatively coupled to the production of inositol phosphates.

Adenosine Diphosphate Ribose↗
PubMed1995

G-protein involvement in muscarinic receptor-stimulation of inositol phosphates in longitudinal smooth muscle from the small intestine of the guinea-pig.

1. Aluminium fluoride (AlF), pertussis toxin (PTX) and cholera toxin (ChTX) have been used to examine the involvement of G-proteins during muscarinic acetylcholine receptor (AChR) stimulation of inositol phospholipid hydrolysis in fragments of longitudinal smooth muscle from the small intestine of the guinea-pig. 2. Carbachol (CCh) induced time- and concentration-dependent increases in [3H]-inositol monophosphates, [3H]-inositol (1,4) bisphosphate, [3H]-inositol (1,3,4) trisphosphate, [3H]-inositol (1,4,5) trisphosphate ([3H]-Ins (1,4,5)P3) and [3H]-inositol tetrakisphosphates measured by h.p.l.c. These increases were inhibited > 95% in the presence of the muscarinic AChR antagonist atropine (0.5 microM). 3. AlF transiently increased the basal levels of [3H]-Ins (1,4,5)P3 but increases in the levels of the other [3H]-inositol phosphates occurred more slowly. CCh-induced increases in the levels of all the [3H]-inositol phosphates were strongly inhibited in the presence of AlF. 4. PTX had no effect on basal levels of any of the [3H]-inositol phosphates but reduced the effects of CCh on these; ChTX had no effects on either basal or CCh-stimulated levels. 5. It was concluded that muscarinic AChR-stimulated increases in the levels of [3H]-inositol phosphates occur via both a PTX-sensitive G-protein and a PTX-insensitive mechanism. The actions of AlF may suggest the involvement of an inhibitory G-protein in the regulation of muscarinic AChR-stimulated inositol phospholipid turnover.

Aluminum↗
PubMed1997

Neuropeptide Y enhances ATP-induced formation of inositol phosphates in chromaffin cells.

Bovine chromaffin cells contain high affinity NPY binding sites coupled through a pertussis toxin-sensitive G protein to inhibition of cAMP accumulation. NPY alone does not alter [3H]inositol phosphate formation from [3H]phosphoinositides in these cells. Increasing NPY concentrations, in the presence of ATP (300 microM), produced a dose-dependent enhancement in [3H]-inositol phosphate formation, EC50 = 3.2 nM. Inclusion of the selective NPY-Y1 receptor antagonist BW1229 (1 microM) produced a marked decrease in NPY potency (EC50 = 3.3 microM). The Y1 receptor agonist, [Leu31, Pro34]-NPY, was equally effective with NPY, whereas NPY18-36, a Y2 receptor agonist, was much less effective. Inclusion of NPY with ATP also produced an enhancement in the release of intracellular Ca2+. The ability of NPY to enhance both [3H]inositol phosphate formation and the release of intracellular Ca2+ was pertussis toxin-insensitive. NPY action on bovine chromaffin cell receptor(s) appears to facilitated by different G proteins: one which can inhibit cAMP accumulation via a pertussis toxin-sensitive process and another which can enhance ATP activation of the inositol phosphate signaling pathway by a pertussis toxin-insensitive process.

Adenosine Triphosphate↗
PubMed1991

Cyclic AMP counteracts mitogen-induced inositol phosphate generation and increases in intracellular Ca2+ concentrations in human lymphocytes.

1. The effects of increases in intracellular adenosine 3':5'-cyclic monophosphate (cyclic AMP) on mitogen-induced generation of inositol phosphates and increases in intracellular Ca2+ concentration were investigated in human peripheral blood mononuclear leukocytes (MNL). 2. The mitogens concanavalin A (Con A), pokeweed mitogen (PWM) and phytohaemagglutinin (PHA) concentration-dependently stimulated generation of inositol phosphates. Catecholamines inhibited this process with an order of potency: isoprenaline greater than adrenaline greater than noradrenaline indicating involvement of beta 2-adrenoceptors. This order of potency was also consistent with the catecholamine potencies for stimulating the generation of cyclic AMP. 3. In addition to catecholamines, the cyclic AMP formation-stimulating agents prostaglandin E1 (PGE1) and forskolin concentration-dependently inhibited mitogen-induced inositol phosphate generation, too. Moreover, the inhibitory effect of isoprenaline was potentiated by co-incubation with the phosphodiesterase inhibitor isobutylmethylxanthine demonstrating that these inhibitory effects were mediated by cyclic AMP. 4. Con A and PHA concentration-dependently increased the intracellular Ca2+ concentration in human MNL (assessed by the fluorescent indicator dye Fura-2). This increase was almost completely blocked by chelation of extracellular Ca2+, demonstrating influx rather than mobilization from intracellular stores. 5. The elevation of intracellular Ca2+ was not blocked by pretreatment with pertussis toxin, 100 ng ml-1, for 16 h. 6. Isoprenaline, PGE1, and forskolin, however, inhibited the mitogen-stimulated elevation of intracellular Ca2+. This inhibition was enhanced by the phosphodiesterase inhibitors isobutylmethylxanthine and Ro 20-1724, demonstrating mediation by cyclic AMP. 7. We conclude that catecholamines and other cyclic AMP increasing agents can inhibit mitogen-stimulated generation of inositol phosphates and elevation of intracellular Ca2+ in resting human MNL.

Adult↗
PubMed1992

Rapid and selective isolation of radiolabelled inositol phosphates from cancer cells using solid-phase extraction.

A method is described for rapid and selective determination of radiolabelled inositol phosphates in cancer cells using solid-phase extraction with Bond Elut strong anion-exchange minicolumns. The inositol phosphates IP1, IP2 and IP3 are selectively eluted with 0.05, 0.3 and 0.8 M ammonium formate-0.1 M formic acid, respectively. Cancer cells are extracted with 10% perchloric acid which is then neutralised prior to loading samples on to the minicolumns. Recovery is 54.1, 66.6 and 61.3% for IP1, IP2 and IP3 with between-day coefficients of variation of 7.6, 6.8 and 1.9%, respectively. When the method was applied to cancer cells high-performance liquid chromatographic analyses confirmed both the identity of the IP1, IP2 and IP3 fractions and showed that there was no detectable cross contamination of these inositol phosphates with each other.

Chromatography, High Pressure Liquid↗