title: Further observation on the lack of active uptake system for substance P in the central nervous system.
abstract: Crude mitochondrial P2 fractions from bovine hypothalamus and substantia nigra, slices from rabbit spinal cord and mesencephalon and glial fractions from rabbit brain were incubated with [3H]-substance P and the uptake was measured and compared with those for 5-HT and GABA. Substance P was to some extent taken up into the fractions but this uptake was neither temperature nor time dependent and the pellet/medium ratios were less than 1. Similar results were obtained in high potassium treated slices from rabbit mesencephalon. The rate of uptake for [3H]-substance P increased linearly in proportion to the medium concentration, suggesting a non-saturable binding. These results, together with our previous observations provide strong evidence that nerve terminals and glial cells lack a temperature sensitive, active uptake system capable of terminating transmitter action of substance P at the synapse.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002490:Central Nervous System / Q000378:metabolism*; D005260:Female; D007031:Hypothalamus / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008636:Mesencephalon / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009457:Neuroglia / Q000378:metabolism; D011817:Rabbits; D012701:Serotonin / Q000378:metabolism; D013116:Spinal Cord / Q000378:metabolism; D013373:Substance P / Q000378:metabolism*; D013378:Substantia Nigra / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D012701:Serotonin; D013373:Substance P; D005680:gamma-Aminobutyric Acid