Using gadolinium to identify stretch-activated channels: technical considerations.
Gadolinium (Gd3+) blocks cation-selective stretch-activated ion channels (SACs) and thereby inhibits a variety of physiological and pathophysiological processes. Gd3+ sensitivity has become a simple and widely used method for detecting the involvement of SACs, and, conversely, Gd3+ 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 Gd3+ 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 Gd3+ in such solutions may reflect the vanishingly low concentrations of free Gd3+ rather than the lack of a role for SACs. Moreover, certain SACs are insensitive to Gd3+, and Gd3+ also blocks other ion channels. Gd3+ 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.
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
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Caldwell
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Clemo
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Baumgarten
D000818:Animals; D004594:Electrophysiology / Q000379:methods; D005188:False Negative Reactions; D005682:Gadolinium / Q000493:pharmacokinetics* / Q000494:pharmacology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008465:Mechanoreceptors / Q000502:physiology*; D008956:Models, Chemical; D015203:Reproducibility of Results
D007473:Ion Channels; D005682:Gadolinium