10 mM sodium kynurenate and 100 mM magnesium chloride.
STERILE after filtration
Kynurenic acid: Sigma K-3375
MW anhydrous = 189.16.
WARNING: Some batches have water of hydration; this will change the calculations.
If anhydrous, 10 mM = (0.01) (189.16) mg/ml = 1.89 mg/ml = 378 mg/200 ml
Magnesium chloride 4.9 M: Sigma 104-20
Need a 49 times dilution of the 4.9 mM solution, so 200 / 49 = 4.08 ml.
|INGREDIENT||Amount for 200 ml of final solution|
|Kynurenic acid||378 mg (if anhydrous)|
|NaOH 0.3 M||6.67 ml|
|Sodium phenol red||0.1 ml|
|Sodium HEPES 500 mM||2.0 ml|
|Magnesium chloride 4.9 M||4.08 ml|
|Autoclaved water||Fill to 200 ml|
It is difficult to dissolve the kynurenate. The solution is typically left in the refrigerator for several days, shaking it once or twice a day. Typically, a tiny amount of the solid fails to dissolve.
The kynurenate solution must be filtered with a pre-washed 0.2 µm nylon filter to remove un-dissolved material and bacteria. The large diameter filter sets are used for 200 ml quantities.
The tubes are then aliquoted and frozen at -20° while being held upright in paper containers. Once the solution has frozen, the tubes can be placed horizontally in the appropriate plastic container in the -20° freezer.
Copyright © 2002 Dr. Michael M. Segal, Department of Neurosurgery, Brigham & Women's Hospital, Boston MA 02115, USA. Many of the solutions are based on recipes from the Furshpan and Potter labs; the recipes given here are the versions we use now in the Segal lab. Individual copies may be made of this page for use in educational institutions.