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KMID : 0365819670070020001
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Journal of Pusan Medical College
1967 Volume.7 No. 2 p.1 ~ p.11
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Changes in Permeability of Blood-Brain Barrier and Injuries of Brain Tissue Following Acute Massive Bleeding
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Abstract
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Experiments were performed on the changes in the permeability of the blood-brain barrier in rabbits following an acute massive bleeding.
Electrolyte balances, especially of potassium concentration in the various compartments of the brain were also studied to detect any possible changes in the function of the central nervous system in the critical circumstances.
Ten rabbits served as the control animals and 14 rabbits were bled. Bleeding was made from the femoral artery as much as 42-45 ml (2% body weight) in 15 minutes after the nembutal anesthetization, 300mg/kg. Ten animals survived for longer than 45 minutes and 4 rabbits died within 45 minutes.
After 5 minutes of intravenous injection of 300 mg of urea, animals were sacrificed and concentrations of urea and electrolytes in arterial blood, superior sagittal sinus blood, cerebrospinal fluid from the cisterna magna and gray matters of brain were determined.
The following results were obtained.
1. The distribution ratio of urea in the brain tissue water, that was, the ratio of the concentration in the brain tissue water versus that of arterial plasma water, increased to 0. 74 in the bled animals in 5 minutes after the injection in comparison with the value 0. 34 in the control animals.
2. There was no appreciable difference in the distribution ratio of urea in the cerebrospinal fluid between the control and the bled animal. The similarity in the appearance of the exogenous urea in both group might be explained on the basis of the slow rate of the fluid formation.
3. The plasma water obtained from the superior sagittal sinus blood showed lower values of urea than that from the arterial blood, suggesting a definite extraction during the circulation in the brain.
4. There was some reduction in the concentration of sodium in the brain tissue water of the bled animals, but no significant alternation in the concentration of potassium was found.
On the contrary, a marked increase in potassium concentration of arterial plasma water was noticed. It rose from 3. 1 mEq/L. H2O to 4.9 mEq/L. H2O.
In the cerebrospinal fluid obtained from the cisterna magna the potassium value showed a minor
increase in comparison with the normal value of 3.0 mEq/L. H20
5. The potassium concentration of the plasma water obtained from the superior sagittal sinus blood in the bled animals showed 8.2 mEq/L. H2O, suggesting a considerable release of potassium from the brain tissue.
6. In the rabbits which died within 45 minutes after the bleeding remarkable increases in potassium concentrations were seen both in the arterial plasma water and in the cerebrospinal fluid, showing 6. 8 and 5. 8 mEq/L. H2O, respectively. The increase in the extracellular fluid does not necessarily mean that the elevation of the concentration of this ion species was directly responsible to the cause of death,
7. All indications illustrated above suggest that an increase of urea permeability in the capillary bed of the brain was brought about by acute massive bleeding and that increase in the potassium concentration at this time can be attributed to appreciable injury occurring in the brain tissue on the occasion.
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