MODIFICATIONS OF THE GLYOXALIC ACID METHOD FOR VISUALIZATION OF CATECHOLAMINES IN VERTEBRATE AND INVERTEBRATE SPECIES

The glyoxalic acid method for demonstration of catecholamines was modified to increase the fluorescence intensity by the use of HEPES [4-(2-hydroxyethyl)-1-piperazine-N''-2-ethanesulfonic acid] buffer in the reaction medium. [Hearts and brains were obtained from Rana temporaria, R. esculenta and R. pipiens and Erinaceus europaeus]. The heating step used in earlier methods was unnecessary with HEPES buffer, and tissue morphology was improved by keeping the whole reaction at 0.degree. C. The fluorescence intensity was not essentially reduced using stored frozen rat brain tissues. The method may accordingly be combined with field work. With HEPES buffer in the medium catecholamines could be demonstrated also in Nereis pelagica. The method may be used in invertebrate and vertebrate species.