Voltage clamp · EPSC · Low chloride
EPSC internal solution recipe
A 50 mL low-chloride Cs-methanesulfonate internal solution starting recipe for whole-cell voltage-clamp recordings of excitatory postsynaptic currents.
Calculate a different volumeDefault batch
50 mL starting recipe
| Compound | Final (mM) | MW (g/mol) | Source | Add |
|---|---|---|---|---|
| Cs-methanesulfonate | 135.0 | 228.0 | Powder | 1539.0 mg |
| HEPES | 10.0 | 238.3 | 100.0 mM stock | 5000.0 µL |
| EGTA | 1.0 | 380.4 | 100.0 mM stock | 500.0 µL |
| MgCl₂ | 4.0 | 203.3 | 1000.0 mM stock | 200.0 µL |
| Mg-ATP | 4.0 | 507.2 | Powder | 101.4 mg |
| Na-GTP | 0.3 | 567.1 | Powder | 8.5 mg |
| Na₂-phosphocreatine | 7.3 | 255.1 | Powder | 93.1 mg |
Why this internal?
A cesium methanesulfonate internal is commonly used for voltage-clamp recordings of excitatory postsynaptic currents. Cesium helps reduce potassium conductances, while the low-chloride composition is intended to keep chloride-mediated currents distinct under appropriately chosen recording conditions.
Actual chloride reversal and current polarity depend on the complete ionic composition, temperature, liquid junction potential, and holding potential. This calculator does not predict ECl or osmolality.
How the amounts are calculated
Powder
mg = mM × mL × MW ÷ 1000
Stock solution
µL = desired mM × final mL × 1000 ÷ stock mM
Before preparing the solution
Treat this as a starting formulation. Verify the exact salt form, hydration state, molecular weight, and assay on each supplier label. Adjust pH experimentally, bring the mixture to final volume, and measure osmolality. The nominal concentration sum is not an osmolality prediction.