iminoglycine and pipecolic-acid

Evidence is presented which suggests that proline, pipecolic acid, and glycine are accumulated by a common transport system in rat brain cortical synaptosomes and synaptosomal plasma membrane vesicles. This system is Na+ dependent and appears to be similar to the iminoglycine transport system present in renal tubules and in renal brush border membranes. The opioid pentapeptides Leu- and Met-enkephalin specifically inhibit the uptake of these three imino/amino acids, presumably by interaction with a nonopioid receptor, since the inhibition is not affected by the opiate antagonist naloxone and occurs with des-tyrosyl enkephalins as well as with the intact pentapeptides.

Topics: Animals; Biological Transport; Cerebral Cortex; Enkephalin, Leucine; Enkephalin, Methionine; Glycine; Imino Acids; Kinetics; Narcotics; Pipecolic Acids; Proline; Rats; Rats, Inbred Strains; Sodium; Synaptosomes