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

Abstract We show that gadolinium (Gd 3+ ) is a potent calcium channel blocker in guinea-pig isolated ventricular myocytes. A dose-dependent inhibition of I Cal was found with an EC 50 of 1.4 μM and a complete inhibition at 10 μM Gd 3+ . When compared with Cd 2+ , it appeared that the blockade of I Cal is a complex phenomenon probably involving more than one site of interaction (a Hill coefficient of 1.6 was found for Gd 3+ vs. 1.0 for Cd 2+ ). It is concluded that Gd 3+ ions completely block I Cal at concentrations used to block stretch-activated channels (SAC), rendering its use as a specific SAC inhibitor problematic.