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.
Caldwell
R A
RA
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Clemo
H F
HF
Baumgarten
C M
CM
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