A practical guide to the preparation of Ca(2+) buffers.

Calcium (Ca(2+)) is a critical regulator of an immense array of biological processes, and the intracellular [Ca(2+)] that regulates these processes is ~ 10,000 lower than the extracellular [Ca(2+)]. To study and understand these myriad Ca(2+)-dependent functions requires control and measurement of [Ca(2+)] in the nano- to micromolar range (where contaminating Ca(2+) is a significant problem). As with pH, it is often essential to use Ca(2+) buffers to control free [Ca(2+)] at the desired biologically relevant concentrations.