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

On the physiology of metazoa

The problem on integration and control of the various processes of the metazoan organism is a major challenge to the physiologist. The traditional research strategy in dealing with the problem is neuron-oriented and its roots extend back into the last century when knowledge of hormones was lacking. In the present article, the traditional strategy is analyzed in the light of available data and its logical basis is questioned. Different levels of communication are supposed to occur in the animal or human body. Circulating hormones are responsible for the highest level of communication that occurs between organs or tissues. The central concept in the article is that regulation of circulating hormones constitutes a higher level of control relative to regulation of intercellular hormones. This is regardless of whether the latter occurs in the nervous system or elsewhere. The approach is utilized in defining the mechanism that integrates and controls the part processes of the body. The mechanism is defined as endothelial; the vascular endothelial system is the controlling part and the nervous system is one of the subordinate parts. Thanks to the new approach, meaningful biological explanations of major psychiatric disorders are now possible.

High-performance liquid chromatographic analysis of beta-phenylethylamine for the estimation of in vivo protein synthesis

A rapid, sensitive, and automated reversed-phase liquid chromatographic method was developed for the analysis of phenylalanine as beta-phenylethylamine, for the measurement of in vivo protein synthesis. beta-Phenylethylamine was derivatized with o-phthaldialdehyde (OPA) to form a fluorescent derivative that was successfully measured in tissue cell fluids and hydrolysates as the decarboxylation product of phenylalanine. The system was extremely sensitive enabling the accurate determination of 0.5 pmol in biological samples. Analysis time was less than 11 min, so that 130 samples can be analysed per day. The method eliminates the need for time-consuming column extraction procedures. This method offers substantial advantages over existing methods for the isolation and determination of beta-phenylethylamine.

Determination of urinary beta-phenylethylamine as its N-benzenesulphonamide derivative by gas chromatography with flame photometric detection

A selective and sensitive method for the determination of urinary beta-phenylethylamine (PEA) by gas chromatography (GC) has been developed. After extraction of the urine sample with n-pentane, PEA was converted into its N-benzenesulphonamide derivative and then determined by GC with flame photometric detection using a DB-1301 capillary column. By using this method, nanogram amounts of PEA in urine could be accurately and precisely determined without any influence from coexisting substances. Analytical results for the determination of PEA in urine samples from normal subjects are presented.

Quantification of plasma phenylethylamine by combined gas chromatography/electron capture negative ion mass spectrometry of the N-acetyl-N-pentafluorobenzoyl derivative

An ultrasensitive method capable of detection and quantification of beta-phenylethylamine in 1 ml of human plasma has been developed using gas chromatography/electron capture negative ion mass spectrometry. Phenylethylamine and tetra-deutero phenylethylamine internal standard in plasma were acetylated, extracted into organic solvent and then further acylated with pentafluorobenzoyl chloride. The N-acetyl-N-pentafluorobenzoyl-phenylethylamines were detected by high-resolution single ion monitoring of the molecular ions. Normal plasma levels were found to be 41.5 +/- 10.7 pg ml-1, in accordance with results of a previous high-performance liquid chromatographic method.

High-performance liquid chromatographic determination of beta-phenylethylamine in human plasma with fluorescence detection

A simple and highly sensitive method for the determination of beta-phenylethylamine in human plasma is investigated. The method employs high-performance liquid chromatography with fluorescence detection. beta-Phenylethylamine and p-methylbenzylamine (internal standard) in human plasma are isolated by cation-exchange chromatography on a Toyopak SP cartridge and then converted into the corresponding fluorescent derivatives with 3,4-dihydro-6,7-dimethoxy-4-methyl-3-oxoquinoxaline-2-carbonyl chloride, a fluorescence derivatization reagent for amines. The derivatives are separated within 30 min on a reversed-phase column, TSK gel ODS-120T, with isocratic elution, and detected fluorometrically. The detection limit of beta-phenylethylamine is 0.3 pmol/ml in plasma (S/N = 3).

Concentrations of beta-phenylethylamine in plasma and plateletes of schizophrenics

The plasma and platelet PEA levels of 20 normal subjects and 17 schizophrenic patients were investigated using a high-performance liquid chromatography. In the normals the mean plasma and platelet levels of PEA were 4.9 +/- 1.9 ng/ml and 1.78 +/- 1.01 ng/mg protein, respectively, while in the schizophrenics, those were 12.1 +/- 7.9 ng/ml and 0.77 +/- 0.5 ng/mg protein, respectively. The plasma PEA levels of the schizophrenics were significantly higher than those of the normals, and the platelet PEA levels of the schizophrenics were lower than those of the normals.

Rapid and sensitive determination of beta-phenylethylamine in animal brains by high performance liquid chromatography with fluorometric detection

A reversed phase HPLC method with fluorometric detection for the analysis of beta-phenylethylamine has been developed using p-methoxyphenylethylamine as an internal standard. Two columns, containing 200 microL of Dowex 50-X8 and Amberlite CG-50 respectively, were used to prepare a fraction containing beta-phenylethylamine. The recoveries of beta-phenylethylamine and p-methoxyphenylethylamine were 53.9 +/- 9.4% and 68.1 +/- 12.4%, respectively, and elution profile of p-methoxyphenylethylamine was sufficiently well correlated with that of beta-phenylethylamine. Regional distributions of beta-phenylethylamine in rat and mouse brains were determined. The highest concentrations were found in hypothalamus and hippocampus in both animals.

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.