Using gadolinium to identify stretch-activated channels: technical considerations

Abstract

Gadolinium (Gd 3+) blocks cation-selective stretch-activated ion channels (SACs) and thereby inhibits a variety of physiological and pathophysiological processes. Gd 3+sensitivity has become a simple and widely used method for detecting the involvement of SACs, and, conversely, Gd 3+insensitivity has been used to infer that processes are not dependent on SACs. The limitations of this approach are not adequately appreciated, however. Avid binding of Gd 3+to anions commonly present in physiological salt solutions and culture media, including phosphate- and bicarbonate-buffered solutions and EGTA in intracellular solutions, often is not taken into account. Failure to detect an effect of Gd 3+in such solutions may reflect the vanishingly low concentrations of free Gd 3+rather than the lack of a role for SACs. Moreover, certain SACs are insensitive to Gd 3+, and Gd 3+also blocks other ion channels. Gd 3+remains a useful tool for studying SACs, but appropriate care must be taken in experimental design and interpretation to avoid both false negative and false positive conclusions.