Uptake of L‐ and D‐Isomers of Catecholamines in Adrenergic Nerve Granules

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 in a concentration of 10 üg/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 μg/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.