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RETENTION AND EXCHANGE OF POTASSIUM IN A SYNAPTOSOMAL FRACTION OF MOUSE BRAIN
Author(s) -
Weinstein H,
Kuriyama K
Publication year - 1970
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.1471-4159.1970.tb00527.x
Subject(s) - potassium , chemistry , sodium , synaptosome , sucrose , biophysics , endogeny , biochemistry , membrane , biology , organic chemistry
— Myelin, synaptosomal and mitochondrial fractions obtained from homogenates of whole mouse brain contain K + which can exchange with 42 K + at 2º in 0·32 m ‐sucrose. The content and rates of exchange of K + were greater at pH 8·2 than at 6·1. In the synaptosomal preparations, the rates of exchange and content of 42 K + and K + declined progressively with decreasing pH. Of the total synaptosomal K + , 95 per cent could exchange with external 42 K + . At pH 7·5, 20 per cent of the K + and 78 per cent of the Na + appeared to reside in osmotically insensitive pools. Synaptosomal K + at 2º was slowly displaced by NaCl (0·18 m ) and the rate of exchange between 42 K + and K + was retarded. KCI (0·18 m ) did not readily displace endogenous Na + . Synaptosomal K + exchanged with exogenous K + more rapidly than with exogenous Na + . These observations have been discussed in terms of possible roles for ion exchange as the principal means by which K + traverses the plasma membrane at 2º.