The Estimation of Small Quantities of 3,4‐dihydroxyphenylethylamine in Tissues

Abstract

Several methods have been used to estimate small amounts of 3,4-dihydroxyphenylethylamine (dopamine) which occur in many plant and animal tissues. The biological assay of dopamine is, by comparison with that of other catechol amines, relatively insensitive. The pressor effect of dopamine on the blood pressure of the rat and the depressor effect observed on the blood pressure of the guinea-pig have been used to assay dopamine extracted from the splenic nerve and stellate ganglion of the ox (Schumann, 1956). These methods are suitable for microgram quantities of dopamine.Of the chemical methods which are applicable to the estimation of dopamine only those involving the formation of a fluorescent derivative are likely to be sensitive enough to estimate the small amounts of dopamine occurring in some tissues. The main fluorimetric methods are based on two chemical reactions.

METABOLISM OF EXOGENOUS NORADRENALINE IN SLICES OF HYPOTHALAMUS AND CAUDATE NUCLEUS OF THE BRUSH‐TAIL POSSUM, TRICHOSURUS VULPECULA

“…The relative distributions of catecholamines in the hypothalamus and caudate nucleus of the possum are similar to those in eutherian mammalian species, e.g.. rat and cat (Glowinski and Iversen, 1966;Laverty and Sharman, 1965), in that NA predominates in the hypothalamus and DA in the caudate nucleus. The concentration of adrenaline is low in both regions, being comparable with DA in the hypothalamus and with NA in the striatum.…”

“…These regions were selected on the basis of evidence that in eutherian mammals the putative catecholamine transmitter in the hypothalamus is NA and in the caudate nucleus is dopamine (DA) (Laverty and Sharman, 1965;Glowinski and Ivcrsen, 1966), By comparing the metabolism of exogenous NA in the two brain regions, it was hoped to define those features of metabolism whieh are specilically related to central noradrenergic transmission.…”

3,4‐Dihydroxyphenylacetic acid and 4‐hydroxy‐3‐methoxyphenylacetic acid in the mouse striatum: a reflection of intra‐ and extra‐neuronal metabolism of dopamine?

“…); n=87. Dopamine was estimated fluorimetrically (Laverty & Sharman, 1965) after adsorption from tissue extracts on to a column of Dowex 50 X-8 cation exchange resin and elution with 2 M hydrochloric acid. Recovery of dopamine added to tissue homogenates was 82 + 4% (S.E.M.…”

The determination of dopamine by a modification of the dihydroxyindole fluorimetric assay

“…A compound suggested to be dopamine was first measured quantitatively in brain (Montague, 1957) by the use of a differential assay procedure based on condensation with 1,2-diaminoethane to obtain a strong fluorescence for total catecholamines (Weil-Malherbe & Bone, 1952) together with a hydroxyindole assay in which the fluorescence contributed by dopamine was very weak (Euler & Floding, 1955). Condensation of 1,2-diaminoethane with the acetylated derivative of dopamine was used in the highly sensitive procedure developed by Laverty & Sharman (1965). A somewhat lengthy purification procedure was used to overcome the inadequate specificity of the assay, but a simplified version was subsequently described (Sharman, 1971).…”