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Regulation of 109 Cd 2+ Uptake into Isolated Neurohypophysial Peptidergic Nerve Terminals
Author(s) -
Toescu Emil C.
Publication year - 1991
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1991.tb06391.x
Subject(s) - chemistry , neuroscience , biophysics , biology
Abstract Cadmium ( 109 Cd 2+ ) uptake was studied in a preparation of isolated neurohypophysial nerve terminals. By use of a filter separation method, together with a permeabilizing agent (Triton X‐100), two cellular Cd 2+ pools have been distinguished. The uptake into the intraterminal pool was governed mainly by a process that displayed saturable kinetics, with a V max of 0.15 nmol of Cd 2+ /mg of protein /min and a K m of 0.18 m M , consistent with a transport system. The superficially bound Cd 2+ pool (Triton insensitive), which represented 30–50% of the total Cd 2+ bound to the cellular system, was very sensitive to the ionic composition of the incubation medium. Reducing the extracellular Ca 2+ or Na + concentration caused a significant increase in the size of the Triton‐insensitive Cd 2+ pool. Whereas Na + did not affect Cd 2+ uptake, Ca 2+ induced a small, but significant, increase of Cd 2+ uptake into the terminals. It is concluded that there is a significant intraterminal uptake of Cd 2+ , which could explain several physiological effects of this ion.