[Elucidation and chemical identification of a heart strength and heart rate-increasing substance from human kidney extracts].

Bioassays involving the measurement of cardioactivity have been used in the past to determine glycoside concentration in post-mortem specimens following glycoside poisoning. This paper describes the presence of a cardioactive principle in alcoholic extracts of kidney that could interfere with these bioassays and which has been identified as tyramine. For the analysis of tyramine a combination of purification methods was employed, including cation exchange with Sephadex CM C-25, gel filtration and HPLC. Detection was achieved using mass spectrometry after careful cation-exchange treatment. The fragmentation pattern with and without prior formation of the TFA-derivative corresponded to that tyramine. IR and UV spectra also indicated the presence of tyramine. Under suitable experimental conditions, positive inotropic and positive chronotropic effects on the right guinea-pig atrium and positive inotropic effect on the left guinea-pig atrium produced by the kidney extract can be shown to differ from those cardiac glycosides. These investigations bring into question earlier court decisions made in legal processes which have been based upon the results of bioassays for the evaluation of cardiac glycoside toxicity.