Preparation of Artificial CSF

Artificial cerebrospinal fluid (CSF) more closely mirrors the composition of endogenous CSF, and is therefore more physiologically compatible. Following is a method for preparing artificial CSF.

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1. Preparation of Solution A

Dissolve in 500 ml pyrogen-free, sterile water:

Compound	(g)
NaCl	8.66
KCl	0.224
CaCl2 · 2H2O	0.206
MgCl2 · 6H2O	0.163

 

2. Preparation of Solution B

Dissolve in 500 ml pyrogen-free, sterile water:

Compound	(g)
Na2HPO4 · 7H2O	0.214
NaH2PO4 · H2O	0.027

 

3. Preparation of Artificial CSF

Combine solutions A and B in a 1:1 ratio.

 

4. Composition of Cerebrospinal Fluid in Various Species 1

Ion/Compound	Human	Dog	Cat	Rabbit
Na	187.5	153.5	160	149*
K	2.6	3.1	4.4	2.9*
Ca	1.1	1.4	1.4	1.24*
Mg	1.1	1.0*	0.7*	0.9*
P	0.8	0.4*	--	--
Cl	119	122	147	99
HCO3	23.3*	25.8*	24.6*	22*

(Concentration in mM)

*Note : Only one reference listed a concentration level. Therefore, the listed value was used.

¹ Ion concentrations (except for the levels indicated with an asterisk) are an average of the data listed in Davson, H. Physiology of the Cerebrospinal Fluid, J. & A. Churchill, Ltd., London, 1967 and Biology Data Book , Volume III, 2nd ed., Fed. Am. Soc. Exper. Biol., Washington D.C., 1974

 

5. Comparison of Real and Artificial CSR Electrolyte Concentrations

Ion/Compound	Cerebrospinal Fluid*	Artificial CSF
Na	154	150
K	3.0	3.0
Ca	1.4	1.4
Mg	0.9	0.8
P	0.4	1.0
Cl	136	155
HCO3	24.1	--

(Concentration in mM)

*Note : Cerebrospinal fluid concentrations are an average of the values listed for the various animal species shown in #4 above.

¹ Ion concentrations (except for the levels indicated with an asterisk) are an average of the data listed in Davson, H. Physiology of the Cerebrospinal Fluid, J. & A. Churchill, Ltd., London, 1967 and Biology Data Book , Volume III, 2nd ed., Fed. Am. Soc. Exper. Biol., Washington D.C., 1974

6. Explanation for the Absence of HCO₃

Bicarbonate was not added to the formula for artificial CSF for two reasons:

• Bicarbonate can cause shifts in the pH of the solution as it converts to CO₂.
• As HCO₃converts to CO₂ , bubbles can develop inside the pump. The presence of a gas in the pump can then affect the pumping rate in unpredictable ways.

Therefore, unless there is an urgent need for using bicarbonate in a study, we strongly recommend that it not be added to the formula for artificial CSF.

 

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