Editor's note: Citation Classics Commentaries were written by the authors of some of the studies that were the most highly cited papers between 1961 and 1975. The essays were originally published between 1977 and 1993 in Current Contents, a publication of the Institute for Scientific Information (ISI), now Thomson Scientific. (ISI was founded by Eugene Garfield, also the founder of The Scientist.) In this edited essay, published in 1979, neuropharmacologist Arvid Carlsson recalls a 1958 paper describing a method for quantifying adrenaline and noradrenalin in tissue extracts.
Arvid Carlsson developed this technique for analyzing adrenaline and noradrenaline levels at the University of Lund, Sweden. The study was cited almost 1,200 times, according to ISI. "The method was quite precise and we had good evidence of both the specificity and sensitivity. That's the reason why I think it became widely used," Carlsson recently told The Scientist...
Using a colorimetric assay, Hillarp and I had discovered in 1956 that reserpine treatment resulted in the virtually complete disappearance of catecholamines from the rabbit adrenal medulla. We were eager to find out what happened to the catecholamines in other tissues. At this time, fluorimetry had started to focus general attention, owing to its high sensitivity and to the recent development of the spectrophotofluorimeter by Bowman and his colleagues.
During a visit to the National Heart Institute, I had become acquainted with and enthused by this instrument. Therefore, rather than trying one of the currently used bioassay procedures, we decided to develop a fluorimetric method for our purpose. An isolation technique had to be developed in order to apply the method for tissue extracts. A weak cation-exchange resin had previously been used for this purpose but could not be used for tissues other than the adrenal medulla.
Essentially, the new thing in our procedure was the introduction of a strong cation-exchange resin (Dowex 50) for the column-chromatographic isolation of the catecholamines, satisfactory results were obtained in terms of tissue blanks, internal standards, recoveries, and activation and fluorescence spectra. Moreover, the identification of adrenaline and noradrenaline in tissue extracts was secured by quantitative paper chromatography.
To account for the widespread use of this method, two additional points should be emphasized. Firstly, the paper describes a simple apparatus that greatly facilitates the chromatographic procedure. Secondly, the method could be further developed to permit the separation and quantitative analysis of a large number of amines and several of their precursors and metabolites in one single chromatographic procedure. This development has recently been reviewed by Atack.
The work reported in our paper was performed at the University of Lund, Sweden, where I held a position as associate professor of pharmacology. My coauthors, Åke Bertler and Evald Rosengren, were medical students. Their contribution was considerable.
At about the same time, our paths separated. I became professor of pharmacology at the University of Göteborg. Several years later Bertler moved to Linköping, where he is professor of clinical pharmacology at the Medical School. Rosengren is associate professor of pharmacology at the University of Lund.
Today our method has several competitors, utilizing not only fluorimetry but also mass fragmentography, isotope techniques based on enzymatic methylations, HPLC, etc. It is hard to predict how long the method will survive. In our, and presumably several other laboratories, it is still the dominant method for the analysis of catecholamines.
Arvid Carlsson, Department of Pharmacology, University of Göteborg, Sweden, July 18, 1979