The stretch-activated ion channel blocker gadolinium also blocks L-type calcium channels in isolated ventricular myocytes of the guinea-pig.

We show that gadolinium (Gd3+) is a potent calcium channel blocker in guinea-pig isolated ventricular myocytes. A dose-dependent inhibition of ICaL was found with an EC50 of 1.4 microM and a complete inhibition at 10 microM Gd3+. When compared with Cd2+, it appeared that the blockade of ICaL is a complex phenomenon probably involving more than one site of interaction (a Hill coefficient of 1.6 was found for Gd3+ vs. 1.0 for Cd2+). It is concluded that Gd3+ ions completely block ICaL at concentrations used to block stretch-activated channels (SAC), rendering its use as a specific SAC inhibitor problematic.