UPTAKE OF L- AND D-ISOMERS OF CATECHOLAMINES IN ADRENERGIC NERVE GRANULES.

Abstract : The spontaneous depletion of endogenous noradrenaline (NA) from bovine splenic nerve granules is diminished or prevented by incubation with either L-NA or D-NA. However, the effect observed following the addition of L-NA is significantly greater than that produced by the D-isomer. No significant difference is observed between the uptake of the two isomers of adrenaline (A) in undepleted granules. The enhanced uptake of A or NA is a concentration of 10 micro-g/ml in the presence of adenosine triphosphate (ATP) similarly did not differ for the L- and D-isomers of the amine. However, the ATP-dependent uptake at an amine concentration of 1 micro-g/ml was 2-3 times as high for L-NA and L-A than for the D-isomers. It is concluded that the ATP-dependent uptake in nerve granules of NA and A at low amine concentrations is to some extent stereospecific, while the amine-uptake at higher concentrations with and without added ATP is not or only slightly dependent on the steric configuration. (Author)