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Biomedical subjects

P M Ceasar

Publications and source records attributed to P M Ceasar.

7 recordsLinked to original sources
PubMed1978

The effect of urinary pH and flow rate on monoamine output.

Three-hour urinary output values of dopamine, noradrenaline, adrenaline, 2-phenylethylamine and p-tyramine were measured in normal volunteers who had been induced, by pretreatment with ammonium chloride or sodium bicarbonate, to excrete maximally acid or alkaline urine. There were significant effects on the excretion of dopamine, adrenaline and 2-phenylethylamine, inversely proportional to urinary pH value. Adrenaline output increased with increasing urinary flow rate. There was a significant correlation between urinary concentrations of 2-phenylethylamine and p-tyramine. These findings may have important clinical implications.

Biogenic Amines↗
PubMed1974

Studies on the metabolism of catecholamines in the central nervous system of the mouse.

1 The distribution of the metabolites of noradrenaline, 1-(3,4-dihydroxyphenyl)ethane-1,2-diol (DOPEG) and 1-(4-hydroxy-3-methoxyphenyl)ethane-1,2-diol (MOPEG), in the brain of the mouse has been investigated.2 The rate of disappearance of the metabolites after inhibition of the enzyme monoamine oxidase has been used to estimate their turnover rates in the mouse hypothalamus. It was concluded that the turnover of DOPEG was much faster than that of MOPEG.3 When mice were treated with reserpine dissolved in 5% ascorbic acid solution there was an increase in the hypothalamic concentration of both MOPEG and DOPEG. However, similar increases in the concentrations of the two metabolites were seen when the animals were treated with 5% ascorbic acid solution alone.4 The administration of tropolone, an inhibitor of the enzyme catechol-O-methyl transferase, resulted in an increase in the concentration of DOPEG.5 Mice, exposed to a temperature of -15 degrees C showed increased hypothalamic concentrations of both DOPEG and MOPEG.6 The rates of formation in the mouse striatum of 3,4-dihydroxyphenylacetic acid (DOPAC) and 4-hydroxy-3-methoxyphenylacetic acid (HVA), acidic metabolites of dopamine, were compared with the turnover rate of dopamine, estimated from the rate at which this catecholamine disappears after treatment with alpha-methyl-p-tyrosine. It was concluded that the estimate of dopamine turnover obtained by this method is likely to be too large because of the compensatory feedback mechanism which is thought to play a role in the metabolism of dopamine in the brain.

Acetylation↗
PubMed1969

Catecholamine and 5-hydroxyindole metabolism in immunosympathectomized rats.

1. The daily urinary excretion of normetadrenaline, metadrenaline, 4-hydroxy-3-methoxyphenylglycol, 4-hydroxy-3-methoxymandelic acid, dopamine, homovanillic acid, 5-hydroxytryptamine and 5-hydroxyindolylacetic acid has been estimated in the urine of immunosympathectomized and control rats.2. A method is given which allows separate spectrophotometric determination of 4-hydroxy-3-methoxyphenylglycol and 4-hydroxy-3-methoxymandelic acid in the same sample of rat urine. Metadrenaline and normetadrenaline were estimated by a modification of the method of Anton & Sayre (1966).3. Approximately 17% of the 4-hydroxy-3-methoxymandelic acid in rat urine is excreted in the free state, over 60% as a glucuronide conjugate and the remainder as a sulphate conjugate.4. Urinary excretion of 4-hydroxy-3-methoxyphenylglycol was approximately halved in immunosympathectomized rats (P<0.001). 4-Hydroxy-3-methoxymandelic acid output was significantly increased in treated animals (P<0.05) when expressed in terms of body weight. No significant difference was detected for any of the other compounds investigated.5. The results are discussed in the light of previous knowledge of the effect of immunosympathectomy on catecholamine metabolism.

Animals↗