BAPTA, Tetrasodium Salt

Ca²⁺-chelator exhibiting a 10⁵-fold greater affinity for Ca²⁺ (110 nM) than for Mg²⁺. After BAPTA complexes with Ca²⁺, the UV spectrum shifts from 254 to 279 nm at pH >6.0. Useful for spectrophotometric monitoring of extracellular Ca²⁺ levels, especially transient phenomena, because of its insensitivity to pH. Has been used for the measurement and control of Ca²⁺ levels in eggs, chromaffin cells, muscle cells, retinal cells, and pancreatic cells. In conjunction with certain formazan dyes, BAPTA can be used in a colorimetric assay for Mg²⁺. Has neuroprotective effects in vitro against excitotoxic damage and spontaneous recurrent seizures, such as epilepsy.

Toxicity: Irritant (B)

Following reconstitution, aliquot, purge with inert gas and freeze (-20°C). To increase stability in solution, store at a high pH (>10). Stock solutions are stable for up to 1 month at -20°C.

DeLorenzo, R.J., et al. 1998. Proc. Natl. Acad. Sci. USA 95, 14482.
Li, L., et al. 1995. J. Cell Physiol. 163, 105.
Tymianski, M., et al. 1994. J. Neurophysiol. 72, 1973.

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