The Distribution of Cations in Plasma and Cerebrospinal Fluid Following Infusion of Solutions of Salts of Sodium, Potassium, Magnesium and Calcium

Abstract

EARLIER experiments, in which the concentration of Mg in the plasma of anaesthetized dogs was maintained at a high level for 5 to 24 hrs, have shown that the Mg* content of cerebrospinal fluid is independent of the plasma level. This suggests that the stability of the Mg concentration in the CSF is maintained by a selective mechanism involving active transport of this ion (KE-, BOLDIZSAR and F'ETHES, 1961). The present report provides confirmation of this idea and also considers the distribution of other cations.Two types of experiment were undertaken. In the first (Type 1, Table 1) the concentration of Mg++ in the plasma was kept artificially high for several hours by means of an intravenous infusion, the water content of which brought about a decrease in the concentration of other plasma cations. In the second type of experiment (Type 2, Table l), a simultaneous rise in plasma K+ and plasma Ca* as well as plasma Mg++ were induced and the effect on the corresponding concentrations in CSF was determined. Experiments of the second type were also carried out in the presence of low plasma sodium concentrations. METHODS Experimental conditionsAcute experiments were performed on 31 mongrel dogs and bitches weighing about 15 kg, under chloralose M~COS~S. The experimental arrangements were similar to those previously described (~N Y , BOLDIZSLR and &TEES, 1961). Two types of infusion were used; details of their composition are given in Table 1.In the second type of infusion experiment, MgSO, solution was infused from a burette inserted into one femoral vein and CaCI, and KC1 solutions were infused into the other of a dog lying on its side.Blood samples were obtained from the jugular vein and CSF samples from the cisterna rnagna. When CSF pressure was continuously registered, samples were taken by means of a T-shaped branch-pipe.

Ionic environment of neurones and glial cells in the brain of an amphibian

“…Our results show that the c.s.f. of Necturus maintains a relatively low concentration of K+ in the face of chronically elevated K+ in blood plasma, and thus we have here a situation that is well known in mammals (Bekaert & IDemeester, 1954;Kemeny, Boldizsar & Pethes, 1961;Bradbury & Davson, 1965;Bradbury & Kleeman, 1967). A similar regulatory mechanism for K+ has also been seen in a more primitive vertebrate, the dogfish (Cserr & Rall, 1967).…”

Cerebrospinal Fluid After Death

“…In the living state, the CSF magnesium is maintained at a level approximately 30 % greater than the serum, and according to Kemeny et al [1961] and Plum [1964], is carefully main tained even if the serum is altered markedly. The amount of zinc nor mally present in the CSF is almost below the range at which accurate measure monts are possible.…”

Magnesium in the Central Nervous System

“…Increasing Mg administration had no strong influence on CSF Mg concentrations. Only small changes in CSF Mg after prolonged supple--mentation were reported in dogs (Kemeny et al, 1961;Schain, 1964). However, chronic dietary Mg deficits led to proportional changes in CSF and brain cellular Mg (Chutkow, 1974).…”