High-performance liquid chromatographic analysis of biogenic amines in biological materials as o-phthalaldehyde derivatives

Derivatization, stabilization and detection of biogenic amines by cyclodextrin-modified capillary electrophoresis-laser-induced fluorescence detection

o-Phthalaldehyde (OPA) derivatives of eight biogenic amines were stabilized at 5 degrees C by forming inclusion complexes with methyl-beta-cyclodextrin (MBCD). The derivatives were separated and detected by cyclodextrin-modified capillary electrophoresis (CE) with UV or laser-induced fluorescence (LIF) detection. Using a borate buffer, pH 9.0 consisting of ethanol and a mixture of negatively charged sulfobutylether-beta-cyclodextrin and neutral MBCD, baseline separation of the eight OPA derivatives was achieved within 25 min with high separation efficiencies. The detection limits (S/N=3) obtained by UV and LIF detection were determined to be 10 microM and 0.250 microM, respectively. Glutamic acid was added after the initial derivatization step to neutralize residual OPA which otherwise caused a significant interference, particularly when analysis was performed around the detection limit of the OPA derivatives. Important biogenic amines in fish, wine and urine were then derivatized and determined by CE-LIF. In the case of sole and rainbow trout, the results obtained were validated by an enzymatic assay using putrescine oxidase.

High-performance liquid chromatographic determination of bradykinin in saliva: a critical review and a new method

Because of difficulties or dubious results with previously published methodologies, a new semi-automated HPLC method with UV absorbance detection was developed and applied to the determination of bradykinin (BK) in human saliva. The new method consisted of an uncomplicated sample preparation involving the addition to saliva of an equal volume of 0.1 M orthophosphoric acid to stabilize BK, vortex-mixing, centrifugation, and separation, followed by chromatography of the supernatant phase on a C8, 150x3.9-mm (I.D.) stainless steel column. The mobile phase was composed of 19% acetonitrile/0.1% trifluoroacetic acid at flow-rate of 0.4 ml/min. Using UV detection at 220 nm, the detection limit was 1 ng/ml for the BK standard, and 7 ng/ml for the assay of endogenous salivary BK. The orthophosphoric acid initially added to the saliva allowed BK to be stabilized from enzymic degradation at 20 degrees C for 5 days and at 4 degrees C for 60 days. Assignment made to the peak with the chromatographic properties of salivary BK was confirmed by HPLC-MS with an electrospray interface. This paper presents a new method that is reproducible, reliable and allows kinetic studies of salivary BK to be performed for clinical investigations.

The determination of histamine in the Drosophila head

Histamine is a neurotransmitter at arthropod photoreceptors. Even though the fruit fly, Drosophila melanogaster, is a widely used model in neuroscience research, the histamine content of its nervous system has not so far been reported. We have developed a high performance liquid chromatography (HPLC) method with pre-column o-phtaldialdehyde-mercaptoethanol (OPA-ME) derivatization and electrochemical detection, to determine this amine in Drosophila. The histamine content of the fly's head averages about 2.0 ng per head. In heads of the mutant hdc(JK910), a presumed null for the gene encoding the enzyme that synthesizes histamine, histamine was not detected in measurable amounts. In heads of the mutant sine oculis, which lacks compound eyes, only 28% of this amine was found compared with wild type flies, so histamine is mainly present in the compound eye photoreceptors. Also observed in histamine-deficient mutants was a decrease in the peak which contains a substance having the same retention time as carcinine (beta-alanyl-histamine). Our method was not able to detect compounds previously reported as histamine metabolites in insects. In spite of this, the method we have developed enables the fast and accurate measurement of histamine in the heads of Drosophila, suitable for screening mutants.

Hydroquinone-based derivatization reagents for the quantitation of amines using electrochemical detection

Two new reagents, NDTE (2,5-dihydroxyphenylacetic acid, 2,5-bis-tetrahydropyranyl ether p-nitrophenyl ester) and HLTE (homogentisic gamma-lactone tetrahydropyranyl ether), are described for the chemical derivatization of primary and/or secondary amines to form an electrochemically active product. These reagents undergo reaction with the aforementioned analytes to form a product possessing the hydroquinone moiety, thus allowing for reversible electrochemical detection at mild oxidation potentials. The reactivity of each reagent was demonstrated by using N-ethylbenzylamine (EBzA) and the dipeptide isoleucine leucine methyl ester as model analytes. The investigation included the isolation and identification of the intermediates and final products from derivatization of EBzA. These isolated standards were subsequently characterized with respect to electrochemical properties by means of cyclic voltammetry. In LC-EC experiments, the concentration limit of detection (CLOD) of the purified EBzA product was determined to be 5 nM (100 fmol) at a detection potential of +200 mV vs Ag/AgCl ([Cl-] = 3 M). The CLOD values obtained by LC-EC after derivatization of aqueous solutions of EBzA and Ile-Leu-OMe with NDTE were 25 nM (250 fmol) and 250 nM (2.5 pmol), respectively.

Histamine and histidine determination in tuna fish samples using high-performance liquid chromatography. Derivatization with omicron-phthalaldehyde and fluorescence detection or UV detection of "free" species

A rapid and simple HPLC procedure for the simultaneous determination of histamine and histidine is presented. Sample extraction, extract purification, derivatization and reversed-phase chromatographic determination are described. Also the analysis of "free" (i.e. not derivatized) species with UV detection is discussed, and the two procedures are compared. A derivatization step involves more difficulties in terms of linearity and reproducibility because of the great unstability of omicron-phthalaldehyde derivatives but presents many advantages due to the good separation between histamine and histidine as far as the increased sensitivity is concerned. The first results of canned tuna samples analysis are presented and discussed.

Simultaneous determination of histamine and serotonin in mast cells by high-performance liquid chromatography

A sensitive and rapid high-performance liquid chromatographic method for the simultaneous determination of histamine and 5-hydroxytryptamine (serotonin) in supernatants and cellular extracts from mouse bone marrow-derived mast cells was developed. The described method is based on a precolumn derivatization of histamine and serotonin with o-phthaldialdehyde (OPA) and subsequent separation of the amine-OPA adducts with an analytical reversed-phase C18 column combined with fluorometric detection (excitation wavelength 360 nm, emission at 455 nm). The mobile phase was 0.02 M sodiumacetate buffer (pH 8) including 5 mM 1-octanesulfonic acid and 50% methanol. The detection limits for histamine and serotonin were 3.3 pmol and 6.9 pmol, respectively (signal-to-noise ratio 2:1). The variations of peak areas of repeatedly injected low or high amounts of amine standards were 23.3% or 6.9% (for 0.5 ng or 12.5 ng histamine) and 26.4% or 4.0% (for 5.0 ng or 250 ng serotonin) during an experimental period of 4 weeks. The variation of retention times over 2 days was 1.1% for histamine and 1.7% for serotonin. A perfect linear relationship of amine concentrations and peak areas was documented by correlation coefficients of r > 0.999 for both histamine (0.1-125 ng) and serotonin (0.5-250 ng).

Human hemofiltrate as a source of circulating bioactive peptides: determination of amino acids, peptides and proteins

Human hemofiltrate (HF) was evaluated regarding its content of free amino acids, proteins, and regulatory peptides. Human HF was obtained from patients with end stage renal disease (ESRD). In contrast to plasma it mainly contains low and middle weight molecules < or = 45 kDa. The content of free amino acids, peptides, and proteins in pooled filtrate was determined by amino acid analysis using ortho-phthaldialdehyde/fluorenyl methyl chloroformate (OPA/FMOC) precolumn derivatization. The total amount of peptides and proteins in human HF is 49.4 mg/L (n = 8). The levels of all free amino acids (230 mg/L) and the concentration of some regulatory peptides like insulin, endothelin, gastrin, vasopressin and angiotensin II were similar compared with blood plasma. The amount of peptides and proteins detected in the filtrate was around 0.07% of total plasma proteins, and consisted mainly of smaller proteins and peptides as shown by size exclusion chromatography (SEC). The presence of large proteins in plasma is reduced by a factor of 1500 after filtration. We conclude that human hemofiltrate is a valuable source for the large-scale extraction of regulatory peptides.

Enantiospecific drug analysis via the ortho-phthalaldehyde/homochiral thiol derivatization method

Pre-column derivatization with o-phthaldialdehyde and an optically active thiol has hitherto been used mainly for liquid-chromatographic chiral separation of amino acids. Chiral separation of non-amino-acid primary amines, especially of pharmaceuticals, via this approach has been largely ignored. We have therefore examined the applicability of the method to the chiral resolution of several pharmaceutical amines. o-Phthaldialdehyde and four commercially available homochiral thiols were used to study the separation of the enantiomers of amphetamine, p-hydroxyamphetamine, p-chloroamphetamine, 3-amino- 1-phenylbutane, 3-amino-1-(4-hydroxyphenyl)-butane, mexiletine, tocainide, tranylcypromine and rimantadine. The resulting highly fluorescent isoindole derivatives were resolved on a Waters Nova-Pak C18 column using mobile phases consisting of mixtures of methanol, a sodium acetate buffer and acetonitrile, and the column effluent was monitored using fluorescence or UV detection. In some cases the fluorescence and/or the UV absorbance of the two diastereomers were unequal. It was found that the resolution of most of the amines could be optimized by varying the homochiral thiol in the derivatization step. This method of chiral separation may have wide applicability in enantiospecific drug analysis of non-amino-acid primary amines due to its simplicity and the high sensitivity it provides.

The determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography

A highly sensitive and rapid method was developed for the determination of histamine in challenged human leukocyte preparations by high-performance liquid chromatography. The assay is based on the Shore's OPT-reaction of the unpurified sample and on a specific separation of the derivate with analytical reversed phase phenyl column combined with spectrofluorometric detection. The detection limit of histamine by this method was 0.07 pmol (signal to noise ratio 2:1) and the within-day variation for peak height was 3.6% and for retention time 0.8%. A good linear standard curve ranging from 12.5 pg to 500 pg (0.07 pmol-2.7 pmol) was obtained with correlation coefficient of 0.998. The histamine release from human basophils in mixed leukocyte preparation was induced by the calcium ionophore A 23187. A concentration of 0.4 micrograms/ml ionophore was required for 50% histamine release with a Ca2(+)-concentration of 1.8 mmol/l. The measured total histamine content was 1.5 pg/basophil.

Determination of urinary free noradrenaline by reversed-phase high-performance liquid chromatography with on-line extraction and fluorescence derivatization

A fully automated reversed-phase high-performance liquid chromatographic method with fluorimetric detection for the determination of urinary free noradrenaline was developed. Urine samples, diluted with buffer were injected into a boric acid gel column (12 microns, TSK: 10 x 4.6 mm I.D.) without prior extraction. Urinary noradrenaline was simultaneously extracted and derivatized with an alkaline mobile phase of pH 11, containing o-phthalaldehyde and 2-mercaptoethanol, in a boric acid gel column. After switching columns, the fluorescent derivatized catecholamines were separated with an ODS-4PW column (TSK) and a mobile phase of pH 2 and the fluorescence was monitored with excitation at 340 and emission at 440 nm. The retention times of noradrenaline and dopamine were 11.0 and 14.2 min, respectively. The detection limits for noradrenaline and dopamine were 0.2 and 20 ng, respectively. This method has the advantages of not requiring preliminary extraction of urinary catecholamines, high sensitivity and stability of o-phthalaldehyde-derivatized catecholamines.

Quantification of L-3-(3-hydroxy-4-pivaloyloxyphenyl)alanine (NB-355) by high-performance liquid chromatography using o-phthalaldehyde/N-acetyl-L-cysteine derivatization

A new and rapid high-performance liquid chromatographic assay has been developed for the determination of L-3-(3-hydroxy-4-pivaloyloxyphenyl)alanine (NB-355,I), a novel prodrug of L-DOPA. The method involves precolumn derivatization of the drug in biological samples with o-phthalaldehyde (OPA) and N-acetyl-L-cysteine (NAC) in a triethanolamine buffer (pH 8.0), giving a fluorescent compound that is stable for 2 h at 4 degrees C. Use of an internal standard improved the assay in accuracy and reliability. A programmable injector allowed automatic derivatization of large numbers of samples. Chromatographic separation was performed on a reversed-phase column (Capcell Pak C18) in which the silica gel was coated with silicone polymer. The peaks corresponding to compound I and the internal standard were eluted within 16 min with a mobile phase of acetonitrile-phosphate buffer (pH 7.1). The reliable limit of quantification was 0.5 pmol per injection (0.05 micrograms equivalents of L-DOPA per ml in plasma). The method was successfully applied for the measurements of dog plasma concentrations after oral dosing of compound I.

Studies on the formation and stability of isoindoles derived from amino acids, o-phthalaldehyde and N-acetyl-L-cysteine

A kinetic-spectrophotometric study is performed on the formation and degradation of the isoindole derivatives of amino acids with o-phthalaldehyde and N-acetyl-L-cysteine. The experimental and structural factors which affect the formation and stability of the compounds are considered, and the results are compared with those obtained for mercaptoethanol. N-Acetyl-L-cysteine derivatives are highly stable, not requiring a strict control of the time of reaction as in the case of mercaptoethanol.

Quantitation of platelet-activating factor by high-performance liquid chromatography with fluorescent detection

Platelet-activating factors, 1-O-hexadecyl- and 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16-AGEPC and C18AGEPC), were measured by reverse-phase high-performance liquid chromatography with fluorescent detection. C16AGEPC, C18AGEPC, and 1-O-hexadecyl-2-propionyl-sn-glycero-3-phosphocholine, which was suitable for use as an internal standard, were hydrolyzed with phospholipase C, and then the resulting hydrolyzed products were derivatized with 7-methoxycoumarin-3-carbonyl chloride or 7-methoxy-coumarin-4-acetic acid to form 7-methoxycoumarin ester derivatives which permit a fluorometric detection. The lower limit of detection of the derivatives was about 100 pg at a signal-to-noise ratio of 5:1. A commercial platelet-activating factor was demonstrated to contain C16AGEPC (70%) and C18AGEPC (12.8%) by the present method. The present method was also applicable to the measurement of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase activity in a lysate of human polymorphonuclear leukocytes.

Formation and instability of o-phthalaldehyde derivatives of amino acids

o-Phthalaldehyde reacts with amino acids in the presence of a thiol to give highly fluorescent 1-alkyl-thio-2-alkyl-substituted isoindoles. However, the instability of the derivatives limits the general utility of the reaction. Mechanistic descriptions of isoindole formation and degradation proposed in the last years, which permit a better understanding of the factors affecting isoindole stability, are presented. The use of alternative thiols and o-phthalaldehyde-like reagents is also reviewed.

A canine model to assess the electrical stability of the transplanted heart

The electrophysiological stability of the transplanted heart under conditions of myocardial ischemia is largely unknown. This problem was studied using a canine model of total cardiac denervation as a substitute for transplantation. Group 1 (N = 3) served as control with placement of ventricular pacing wires only. Group 2 (N = 3) underwent total cardiac denervation with placement of ventricular wires. Group 3 (N = 8) underwent total cardiac denervation with subsequent ligation of the left anterior descending coronary artery and collaterals to the apex. Group 4 (N = 9) underwent coronary artery ligation only. Chronic electrophysiological studies were conducted in all groups in the conscious state. Electrophysiological variables were determined from continuous Holter monitoring of the ECG, determination of strength-interval curves, and assessment of the inducibility of ventricular tachycardia by premature programmed pacing. In general, the denervated, infarcted group (Group 3) consistently demonstrated a greater level of electrical stability than the infarcted animals with normal innervation (Group 4).

High-performance liquid chromatographic analysis of neurotransmitter amino acids in brain

Rapid and selective determination of neurotransmitter amino acids in rat and human brain is accomplished by pre-column derivatization with o-phthaldehyde-3-mercaptopropionic acid, reversed-phase high-performance liquid chromatographic separation, and fluorimetric detection. Aspartate, taurine, glutamate, and glycine are determined in less than 12 min with intra- and inter-assay precisions of 2.1-9.5% and 4.2-9.2%, respectively. gamma-Aminobutyric acid is determined in less than 8 min with intra- and inter-assay precisions of 1.6 and 11.7%, respectively. Both assays utilize internal standards and require a minimum of sample preparation.

Resolution of alpha-substituted amino acid enantiomers by high-performance liquid chromatography after derivatization with a chiral adduct of o-phthalaldehyde. Application to glutamic acid analogues

The fluorescent diastereoisomeric adducts formed in a precolumn derivatization reaction of enantiomeric alpha-substituted amino acids with o-phthalaldehyde and N-acetyl-L-cysteine were separated by high-performance liquid chromatography on a conventional reversed-phase column. This method was particularly efficient for the complete analytical resolution of alpha-substituted glutamic acid analogues, such as 2-methylglutamic acid, and several cyclic analogues (1-amino-1,3-dicarboxycyclohexane, 1-amino-1,3-dicarboxy-2-cyclohexene and 1-amino-1,3-dicarboxycyclopentane). The order of elution from the column was correlated with the absolute configuration of the derivatives.

Postcolumn fluorometric detection system for liquid chromatographic analysis of amino and imino acids using o-phthalaldehyde/N-acetyl-L-cysteine reagent

A high-performance liquid chromatographic system for the determination of amino acid and imino acid was developed using a two-step reaction with sodium hypochlorite and o-phthalaldehyde/N-acetyl-L-cysteine (OPTA/AcCys) reagent. This reagent improved the sensitivity in the analysis of proline presumably because the fluorophore is more stable to hypochlorite which has been used for the oxidative cleavage of the imino linkage. The use of OPTA/AcCys facilitated the detection of imino acids at the same concentration level as that of amino acids. The detection limit for all the amino and imino acids was a few picomoles. This detection system, together with cation-exchange chromatographic separation, was applied to the determination of amino and imino acids in biological samples.

Determination of serotonin and 5-hydroxyindoleacetic acid in urine by reversed-phase ion-pair partition chromatography with fluorimetric detection

The determination of serotonin and 5-hydroxyindoleacetic acid in urine is described. The compounds are separated by means of reversed-phase chromatography using tri-n-butylphosphate as the stationary phase and a mobile phase containing perchlorate as an ion-pairing agent. Detection is performed fluorimetrically. The compounds can be assayed directly, using two mobile phases with different pH values. Alternatively, both compounds can be determined with the same mobile phase after urine extraction on a small XAD-2 column for clean-up of serotonin. Two different approaches were evaluated for this XAD-2 extraction, viz.: (i) desorption of serotonin with a methanol-rich solvent after a washing step with an aqueous solvent; (ii) direct desorption of serotonin in the washing step using a solvent with a small percentage of methanol. Only the latter approach proved to be successful. The linearity of the method was investigated by standard additions to urine. The method was applied to the determination of both compounds in urine. The stability of the compounds in standard solutions and in urine was investigated under various storage conditions.

High-performance liquid chromatographic determination of urinary catecholamines by pre-column solid-phase dansylation on alumina

Sensitive and selective high-performance liquid chromatographic determination of catecholamines by pre-column solid-phase dansylation is described. After catecholamines are adsorbed on alumina, the amino groups not responsible for adsorption are dansylated by a solid-phase reaction. The excess reagent and fluorescent contaminants are washed out, and the dansylated catecholamines are eluted and separated by reversed-phase high-performance liquid chromatography. The four catecholamine derivatives can be separated within 10 min and no major interfering peak is observed on chromatograms. The response of each catecholamine is linear from 10 to 500 pmol per sample and the detection limit is 0.5 pmol. This method was applied to determination of catecholamines in human urine.

Determination of beta-phenylethylamine concentrations in human plasma, platelets, and urine and in animal tissues by high-performance liquid chromatography with fluorometric detection

A highly sensitive method for the determination of beta-phenylethylamine in human plasma, platelets, and urine and in mouse tissue is described. The method is based on a two-step isolation using cation-exchange columns followed by reverse phase high-performance liquid chromatography with fluorometric detection. The recovery of the amine through the whole procedure was almost complete, ranging from 99 to 101%. The calibration graph appeared linear over the range of 50 to 5000 pg/injection. Urinary excretion of beta-phenylethylamine in humans ranged from 0.93 to 51.20 ng/mg creatinine. The amine was also detectable in plasma and platelets. Of the various mouse tissues examined, the highest concentrations were found in the small intestine, followed by the blood and liver. Concentrations of about 5 ng/g wet wt were detected in brain tissue, which increased remarkably after inhibition of monoamine oxidase by pargyline.

Biological functions of serine proteases in the granules of rat mast cells

The effects of specific low- and high-molecular weight inhibitors of chymase and tryptase and F(ab')2 of antichymase on histamine release from activated mast cells were examined. The release of histamine induced by anti-rat immunoglobulin E was markedly inhibited by F(ab')2 fragments of antichymase and the low-molecular weight inhibitor of chymase chymostatin, whereas release of histamine induced by calcium ionophore A23187 was inhibited only by chymostatin. Neither the inhibitor nor the antibody affected histamine release induced by compound 48/80. These results suggest that two main chymotrypsin-type proteases are involved in process of degranulation: one is chymase, which acts at a step before calcium entry, and the other is an unidentified protease, which acts at a step after calcium entry. These results are summarized in Figure 8. After degranulation, released chymase remains associated with the cell surface while released tryptase was found in the extracellular milieu. Tryptase converted bovine prothrombin to thrombin, as shown by increase in thrombin activity with a synthetic substrate, t-butyloxy-carbonyl-Val-Pro-Arg-4-methyl-coumaryl-7-amide. The apparent Km value toward prothrombin was relatively low (2.3 microM), suggesting that tryptase contributes to blood coagulation or the process of fibrosis in tissues. The proteolytic products of IgG1 produced by chymase had chemotactic activity for neutrophil leukocytes in vitro and in vivo. These findings indicate the possible functions of these proteases after degranulation.

Histamine food poisoning: toxicology and clinical aspects

Histamine poisoning can result from the ingestion of food containing unusually high levels of histamine. Fish are most commonly involved in incidents of histamine poisoning, although cheese has also been implicated on occasion. The historic involvement of tuna and mackerel in histamine poisoning led to the longtime usage of the term, scombroid fish poisoning, to describe this food-borne illness. Histamine poisoning is characterized by a short incubation period, a short duration, and symptoms resembling those associated with allergic reactions. The evidence supporting the role of histamine as the causative agent is compelling. The efficacy of antihistamine therapy, the allergic-like symptomology, and the finding of high levels of histamine in the implicated food suggest strongly that histamine is the causative agent. However, histamine ingested with spoiled fish appears to be much more toxic than histamine ingested in an aqueous solution. The presence of potentiators of histamine toxicity in the spoiled fish may account for this difference in toxicity. Several potentiators including other putrefactive amines such as putrescine and cadaverine have been identified. Pharmacologic potentiators may also exist; aminoguanidine and isoniazid are examples. The mechanism of action of these potentiators appears to be the inhibition of intestinal histamine-metabolizing enzymes. This enzyme inhibition causes a decrease in histamine detoxification in the intestinal mucosa and results in increased intestinal uptake and urinary excretion of unmetabolized histamine.

Detection by HPLC-EC of primary amines recovered in aqueous push-pull perfusates from cat cuneate nucleus

A method is described for the quantitative detection of primary amines - particularly free amino acids - recovered in aqueous push-pull perfusates obtained from the cat cuneate nucleus. Isoindole derivatives of primary amine groups are formed by precolumn reaction with o-phthalaldehyde and mercaptoethanol. Derivatized sample components are separated and detected using HPLC with electrochemical detection. Of 22 amino acids standards studied individually, 12 were detectable under the conditions described. Variability of elution times and detector output peak heights were less than 2% and less than 10%, respectively. Concentration curves were linear to the 10 picomole order of magnitude. For cuneate nucleus perfusates, samples recovered during continuous peripheral somatosensory stimulation contained detectable derivative levels elevated above those of control samples. Sources of error in data interpretation are discussed.

Plasma levels of norepinephrine and epinephrine during malignant hyperthermia in susceptible pigs

Malignant hyperthermia (MH) is a genetic disease of man, swine, dogs, cats, and horses. The syndrome is normally triggered by inhalational anesthetics or the administration of depolarizing muscle relaxants such as succinylcholine or various environmental stress factors. We have used the MH-susceptible pig as an animal model to study the hormonal changes developing during this highly lethal syndrome. High-performance liquid chromatography with electrochemical detection was used for the quantitation of the plasma levels of norepinephrine and epinephrine during MH. This research presents evidence that the rapid release of massive quantities of norepinephrine (up to 108 ng/ml) into the blood stream occurs simultaneously with the initiation of tachycardia which is the herald signal of the onset of MH. Norepinephrine levels exceed epinephrine by a 4:1 ratio early in the syndrome. Even pigs with MH which do not develop the muscle rigor phase have high levels of circulating norepinephrine. Tachycardia, pulmonary hypertension, increased venous oxygen desaturation, and increasing core temperature develop as the syndrome progresses.

Interaction between the baroreflex and anterior hypothalamic stimulation. Demonstration of a noradrenergic involvement

Cats, anaesthetized with alpha-chloralose, were used to investigate an interaction between the baroreceptor reflex and stimulation of the anterior hypothalamus (AH). In these cats, stimulation of the anterior hypothalamus gave autonomic responses that characterize the defense reaction. Stimulation of the anterior hypothalamus also interacted with the baroreceptor reflex without altering the effectiveness of the vasodepressor component of the reflex (induced by stimulation of the aortic nerves). However, in spinal cats the bradycardia component (induced by angiotensin at 0.097 nmol/kg pe min, i.v.) was inhibited by stimulation of the anterior hypothalamus and the inhibition was augmented by pretreatment with phentolamine (17.7 nmol) in the nucleus tractus solitarius (NTS). Pretreatment with phentolamine (17.7 nmol) in the nucleus tractus solitarius also reduced the sensitivity of the bradycardia component of the reflex and attenuated (3 and 6 nmol) the induced inhibition of the bradycardia induced by stimulation of the anterior hypothalamus. This attenuation induced by NE was abolished by pretreatment with phentolamine (17.7 nmol), but not by pretreatment with sotalol (16 nmol) or haloperidol (12 nmol) in the nucleus tractus solitarius. Additionally, NE was released from the nucleus tractus solitarius during activation of the baroreceptor and during stimulation of the anterior hypothalamus in cats with intact baroreceptor nerves, but not in baroreceptor-denervated cats. Moreover, the baroreceptor reflex attenuated the pressor response evoked by stimulation of the anterior hypothalamus, and also caused the release of NE from the anterior hypothalamus. At this site, injection of NE (3 and 6 nmol) attenuated the pressor response evoked by stimulation of the anterior hypothalamus and this attenuation was abolished by pretreatment with phentolamine (17.7 nmol), but not by pretreatment with sotalol (16 nmol) or haloperidol (12 nmol) in the anterior hypothalamus. It is concluded that NE participates at the nucleus tractus solitarius and the anterior hypothalamus as an attenuator in the interaction between the baroreflex and stimulation of nerve fibers in the anterior hypothalamus that mediate the defense reaction.

Prostaglandin D2 and prostaglandin D synthetase in mast cell deficient mice

The content of prostaglandin D2 (PGD2) and the activity of PGD synthetase were measured in various tissues of mutant mice deficient in tissue mast cells (W/Wv) and congenic normal mice (+/+). The amounts of PGD2 were determined by the radioimmunoassay specific for PGD2. PGD2 was found in all tested tissues including brain, lung, stomach, spleen and skin of both genotypes in concentrations of a few to about thirty ng/g wet weight tissue, and in spite of the absence of tissue mast cells and the very low content of tissue histamine in W/Wv mice, there was no difference in tissue PGD2 amounts between W/Wv and +/+ mice. The activity of PGD synthetase was assayed in supernatant fraction (10,000 X g, 20 min) of tissue homogenates in the presence or absence of 1 mM GSH. All the tissues of both genotypes listed above showed considerable activity of PGD synthetase, and no difference in tissue PGD synthetase activity was found between W/Wv and +/+ mice. These results suggest that mast cells contribute little to the total amount of PGD2 and PGD synthetase activity in various tissues of mice, and that tissues can synthesize PGD2 independently of tissue mast cells.

Effect of temperature stress on circulating biogenic amines in bovine

A sensitive, simple and selective chromatographic method using high performance liquid chromatography was developed to measure circulating levels of histamine (HI), norepinephrine (NE), dopamine (DA) and serotonin (5-HT) as indicators of response to thermal stress in two breeds of cattle. Duplicate exposures for 8 hr to 13 degrees C resulted in significantly elevated plasma NE and DA in longhorns but not in Herefords and suggest a relatively greater sensitivity to the cold (13 degrees C) in the longhorn. Environmental temperatures of 32 and 42 degrees C significantly increased rectal temperatures of both breeds with much higher rectal temperatures in Herefords. The 32 and 42 degrees C effects on circulating NE and DA of Herefords were highly significant but not in the longhorn. However, heat stress significantly elevated HI and 5-HT in the longhorn which may account for their relatively greater heat tolerance based on their lower rectal temperatures.

Analysis of polyamines and acetyl derivatives by a single automated amino acid analyzer technique

In a single, rapid and precise analysis, monoacetylputrescine, N8-acetylspermidine, N1-acetylspermidine, putrescine, spermidine, and spermine can be separated using a five-buffer system on an automatic amino acid analyzer. This method allows, for the first time, the separation of all the known acetyl derivatives of putrescine and spermidine as well as the parent compounds in urine and tissues with a single automated procedure. The method has been applied to the analysis of biological samples from normal volunteers, cancer patients and a rat liver supernatant. Mass spectral confirmation was obtained for each compound.

Determination of mono-, di- and polyamines in foods using a single-column amino acid auto-analyzer

A fully automated, rapid and sensitive method was developed to analyze fourteen different biogenic amines in food. Using a Technicon C4 ion-exchange resin column (20 m X 0.5 cm), adapted to an automatic Technicon TSM amino acid analyzer, the following amines were separated and quantified: adrenaline, noradrenaline, 1,3-diaminopropane, putrescine, cadaverine, histamine, spermidine, dopamine, spermine, agmatine, tyramine, serotonin, phenethylamine and tryptamine. Five buffers were required to elute the amines using a gradient of pH from 5.6 to 12.7; the column temperature was maintained at 65 degrees C. The method was also assayed on ground beef, cheese and wine samples. Amines from cheese and ground beef samples were extracted with 0.6 M perchloric acid. No extraction of wine samples was necessary.

An investigation of high-performance liquid chromatographic methods for the analysis of amphetamines

Three pre-column derivatization reagents, namely o-phthalaldehyde, 4-chloro-7-nitro-benz-2,1,3-oxadiazole, sodium naphthaquinone-4-sulphonate and two ion-pair reagents, namely, naphthalene-2-sulphonate and sodium dodecylsulphate have been investigated for their suitability for the qualitative and quantitative analysis of urine and plasma samples containing amphetamines. The derivatization method employing sodium naphthaquinone-4-sulphonate was found to be selective and sufficiently sensitive for the routine determination of amphetamine and methylamphetamine in urine and plasma samples at the ng/ml level.

Influence of formamidines on biogenic amine levels in rat brain and plasma

Biogenic amine levels in samples of whole brain and plasma following treatment of rats with chlordimeform (CDF), its two N-demethyl metabolites (DMC and DDC), p-chloroamphetamine (PCA), and harmaline were separated by high performance liquid chromatography equipped with fluorescence or electrochemical detection systems. At 1 hr following s.c. injection, CDF (200 mg/kg) caused a reduction in levels of norepinephrine (NE), 5-hydroxytryptamine (5-HT), and tyramine (TRM), an increase in dopamine (DA), and no change in levels of beta-phenethylamine (PEA) in samples of whole rat brain, whereas DMC (100 mg/kg) and DDC (25 mg/kg) effected reductions of brain levels of NE, 5-HT, TRM, and PEA with no change in DA. The effect of DMC (100 mg/kg) on NE and DA levels in brain was followed periodically for 24 hr. Following a significant decrease at 1 hr, NE levels increased to a maximum at 12 hr and remained higher than controls throughout the remainder of the 24 hr test period. DA levels increased during the initial 12 hr and remained significantly higher than controls for the remaining 12 hr. The influence of s.c. vs i.p. administration of DMC (100 mg/kg) on brain amine levels was examined. Intraperitoneal treatment generally resulted in lower amine levels in DMC and vehicle treated animals. Differences in treatment effects were similar for all amines except for 5-HT in which s.c. injection produced a slight reduction, while i.p. injection resulted in a two-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

High performance liquid chromatography of pharmacologically active amines and peptides in biological materials

Precise and quantitative reversed-phase high performance liquid chromatographic (HPLC) procedures are described which can be used in biogenic amine and neuropeptide research. The amine procedure was applied to various pharmacological matrices including plasma, heart tissue and brain. The use of peptide HPLC as an analytical tool for various neuropeptides is illustrated by studies on des-tyrosine-gamma-endorphin (DT gamma E) metabolism in the brain and the stability of an ACTH (ORG-2766) analogue during a chronic infusion in rats. The power of HPLC as a research tool in peptide pharmacology is described, discussed and demonstrated as an aid in the understanding of the pharmacological effects of exogenous peptides and the function of the brain.

Pre-column derivatization and high-performance liquid chromatography of biogenic amines in blood of normal and malignant hyperthermic pigs

A sensitive, selective, pre-column derivatization method was used with high-performance liquid chromatography to measure norepinephrine, dopamine and serotonin in plasma from normal and malignant hyperthermic (MH) pigs. Samples were carefully collected from control and stressed animals under halothane anesthesia. Using a simple extraction method involving pre-column derivatization with o-phthaladehyde and ethyl acetate partitioning, the samples were chromatographed in less than 50 min. Norepinephrine was found to be elevated in MH pigs as the syndrome progressed, reaching levels eight-fold greater than control pigs under anesthesia. These experiments provide some evidence for our hypothesis that a failure to metabolize excess norepinephrine may be one of the key metabolic defects in causing the pathophysiology of the malignant hyperthermia-stress syndrome. The application of our chromatographic method in animal and human tests may provide a pattern of biogenic amine types and levels that could be diagnostic in identifying susceptible humans and carrier animals.