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SummaryThree semi-automated procedures are described for the estimation of the catecholamine contents of urine, tissue and plasma samples. The three procedures are based on the fIuorometric tri-hydroxyindole assay which has been modified for automatic analysis. These techniques offer several advantages over currently available assays in that they are more convenient, provide for faster analysis rate and give increased sensitivity. The results of the present studies in which the catecholamine contents of urine, tissue and plasma samples were determined using the semi-automated assay provided a range of values which was identical to that obtained using other methods.Australian Journal of Experimental Biology and Medical Science (1977) 55, 213–223; doi:10.1038/icb.1977.15

SummaryElectrolysis of 3-niethoxycatecholamines in physiological solutions resulted in the formation of the parent catecholamines and their oxidation products. Conversion occurred at the anode. Maximal catecholamine production occurred in the presence of ascorhic acid.Australian Journal of Experimental Biology and Medical Science (1976) 54, 35–42; doi:10.1038/icb.1976.4

SummaryA sensitive automated assay was developed for the determination of histamine.The endogenous histamine content of intact rabbit thoracic aorta, and of its separated adventitial and medial layers was determined. The histamine content of the intact aorta was found to be only partially sensitive to compound 48/80.The isolated aorta accumulated labelled histamine against a concentration gradient, The uptake was abolished by cooling to 1°, but was unaffected by oxygen lack.The uptake process was sensitive to a variety of agents including extraneuronal catecholamine uptake inhibitors (deoxycorticosterone acetate, normetanephrine) as well as inhibitors of catecholamine and histamine metabolism (tranylcypromine, hydralazine).The uptake was not affected by amodiaquin, a histamine N-methyl-transferase inhibitor, by the metabolites 1.4-methylhistamine or imidazole acetic acid, by compound 48/80 or by the basic amino acid arginine.Australian Journal of Experimental Biology and Medical Science (1977) 55, 89–102; doi:10.1038/icb.1977.8

SummaryFluorimetric assay of the central artery of the rabbit ear yielded mean noradrenaline and adrenaline contents of 0·89 and 0·08 μg./g. respectively. This finding is consistent with previous histochemical observations and tends to exclude the possibility that adrenaline is of importance in neurotransmission in the rabbit ear.Australian Journal of Experimental Biology and Medical Science (1967) 45, 707–709; doi:10.1038/icb.1967.71