title: Uptake and release of kyotorphin in rat brain synaptosomes.
abstract: Uptake and release of kyotorphin (Tyr-Arg) in rat brain synaptosomes were studied. Synthetic kyotorphin was taken up into crude synaptosomes (P2), in a temperature-dependent manner. The Km and Vmax of the uptake were 1.31 +/- 0.12 X 10(-4) M and 5.9 +/- 0.5 pmol/mg protein/min, respectively. Metabolic inhibitors such as dinitrophenol and iodoacetamide and ouabain which is known as an inhibitor of Na+ dependent uptake mechanism significantly inhibited the uptake. When the synaptosomes previously preloaded with synthetic kyotorphin at 10(-4)M were exposed to high K+ medium, kyotorphin was released in a Ca2+-dependent manner. These findings support the view that kyotorphin plays a role as neurotransmitter/neuroregulator.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000502:physiology; D003864:Depression, Chemical; D004140:Dinitrophenols / Q000494:pharmacology; D004723:Endorphins / Q000378:metabolism*; D007460:Iodoacetamide / Q000494:pharmacology; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D004140:Dinitrophenols; D004723:Endorphins; C019448:kyotorphin; D010042:Ouabain; D011188:Potassium; D002118:Calcium; D007460:Iodoacetamide