ВЛИЯНИЕ Gd 3+ И Ca 2+ НА СОКРАТИМОСТЬ СЕРДЕЧНОЙ МЫШЦЫ ЛЯГУШКИ И ДЫХАНИЕ, НАБУХАНИЕ И ПОТЕНЦИАЛ ВНУТРЕННЕЙ МЕМБРАНЫ МИТОХОНДРИЙ СЕРДЦА КРЫСЫ

The inotropic and chronotropic effects of gadolinium ions (Gd3+) were studied in heart muscle preparations of the frog Rana ridibunda. In addition, the influence of Gd3+ on oxygen consumption rates, swelling and the inner membrane potential (∆Ψmito) were studied in glutamate and malate energized rat heart mitochondria (RHM). It was found that Gd3+ decreases the amplitude and frequency of spontaneous heart contractions. At the same time, Gd3+ prevents Ca2+ -induced swelling of these organelles in salt media and falling ∆Ψmito. In this case, regardless of the presence of Ca2+  in the medium, Gd3+ has a weak effect on mitochondrial state 3 or 3UDNP respiration (in the presence of 2,4-dinitrophenol). In calcium free experiments, Gd3+ stimulates passive swelling of RHM. These effects of Gd3+ may indicate that Gd3+ does not exert a toxic effect on RHM but, on the other hand, inhibits opening of the mitochondrial permeability transition pore (MPTP) in the inner membrane. Our data provide better insight into the mechanisms of action of rare earth elements on Ca2+ -dependent processes in the myocardium of vertebrates.