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THE MECHANISM OF THE EXCLUSION OF SODIUM IONS AND THE CONCENTRATION OF POTASSIUM IONS BY GUINEA‐PIG CEREBRAL CORTEX SLICES
Author(s) -
Hillman H.,
Stollery Susan,
Joanny P.
Publication year - 1974
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.1471-4159.1974.tb06897.x
Subject(s) - incubation , sodium , potassium , choline , chemistry , swelling , bicarbonate , guinea pig , cerebral cortex , isotonic , ion , isotonic saline , chromatography , biochemistry , medicine , endocrinology , biology , organic chemistry , pathology
—Guinea pig cerebral slices were incubated in oxygenated Krebs‐Ringer bicarbonate glucose saline for periods of 1 s to 60 min, and their swelling and Na + and K + cone were measured. The swelling was at the rate of 8 per cent for the 1st min, and 0·8 per cent for the next 29 min; it fell significantly during the subsequent 30 min ( P = 0·05). The Na + and K + concn in the tissue fluctuated during the 1st min of incubation, but the Na + concn had risen to a mean of 108 m m after 1 min incubation and the K + concn had fallen to a mean of 52 m m by 3 min. The concentrations of these cations did not change significantly after these times. Cerebral slices were also incubated for 30 min in isotonic media modified such that Na + , + K + , Na + + choline + , or K + + choline + always added up to 150 m m . It was found that about half of the swelling (20‐25 per cent) was independent of the Na + or K + concn and a further 20‐25 per cent of the swelling varied with the cations only if Na + and K + were both present and was a function of the K + concn in the medium (0·15 per cent m‐mol). The Na + concn in the tissue was a mean 8·4 m m after incubation in a Na + ‐free medium and 7·1 m m in K + after incubation in a K + ‐free medium. Cerebral slices in the presence of Na + + K + excluded one molecule of Na + for every four molecules in the incubating medium; they accumulated K + from the medium until the concn in the medium exceeded 130 m m .