Preparation of Artificial CSF

Artificial cerebrospinal fluid (aCSF) is commonly used as a vehicle solution for administration of test agents to the central nervous system (CNS) of laboratory animals. Listed below is a suggested method for the preparation of artificial CSF. This solution closely matches the electrolyte concentrations and physiological compatibility of endogenous CSF.

1. Preparation of Solution A

Weigh appropriate amounts of each compound listed below and 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

Weigh appropriate amounts of each compound listed below and 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. Equal volumes of each solution are required to end up with a multivalent physiological ion solution of aCSF.

Recomended Storage Conditions: The aCSF solution may be stored at 4 degrees Celsius for up to 4 weeks. If the solution becomes cloudy, or there is indication of precipitation, discard and make a fresh batch. To preserve the pH and quality of the aCSF solution, we recommend making a fresh batch of the mixed solution (A and B) as needed. Solution A is a mixture of salts, and solution B is a mixture of buffers. When separate, solutions A and B may be stored at 4 degrees Celsius for longer periods. When mixed together, the solution is more prone to microbiological growth, thus it is recommended to store solutions A and B separately, and mix as needed.

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*

(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

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*

5. Comparison of Real and Artificial CSF 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.

 

Pump Advantages

  • Ensure around-the-clock exposure to test agents at predictable levels
  • Permit continuous administration of short half-life proteins and peptides
  • Provide a convenient method for the chronic dosing of laboratory animals
  • Minimize unwanted experimental variables and ensure reproducible, consistent results
  • Eliminate the need for nighttime or weekend dosing
  • Reduce handling and stress to laboratory animals
  • Small enough for use in mice or very young rats
  • Allow for targeted delivery of agents to virtually any tissue
  • Cost-effective research tool

 

Request a custom bibliography search or select from our list of citations available on-line:

Researchers are saying...

“We developed the optic nerve/osmotic pump infusion technique to deliver soluble ligands, agonists, or antagonists directly into the optic nerve.The advantages of this technique are that the infused drugs remain largely confined within the experimental nerve, reducing the impact of potential systemic side effects; mere placement of the catheter and subsequent infusion of the vehicle solution do not promote lesion-like changes within the optic nerve…” Rodgers et al., GLIA 41:180-190; 2003.