Gadolinium as an Inhibitor of Ionic Currents in Isolated Rat Ventricular Cardiomyocytes
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The whole-cell patch-clamp technique was used to examine the effect of gadolinium Gd3+ (a non-specific blocker of mechanically gated current IMGCh, a component of late current IL) on ionic currents in insolated rat ventricular cardiomyocytes alone and in combination with the blockers of L-type calcium currents (ICaL) nifedipine (10 μM) or verapamil (1 μM). In K+in/K+out or Cs+in/Cs+out media, blockade of ICaL produced no effect on IL at negative potentials, but inhibited IL at positive ones. In K+in/K+out medium, Gd3+ (5 μM) decreased the net persistent current (Inp) at -45 mV from 198.6±6.4 to 96.7±9.5 pA over 15 min. Gd3+ alone or in combination with ICaL blockers shifted the reversal potential of IL to more negative values. At negative potentials, Gd3+ decreased IK1 and inward current including IMGCh. At positive potentials, Gd3+ alone or in combination with ICaL blockers decreased IL. When applied for 15 min in Cs+in/Cs+out medium at -45 mV, Gd3+ produced no effect on net current and inward and outward components of IL. Thus, Gd3+ can be viewed as a specific blocker of IMGCh only in Cs+ medium.
Key Wordsrat isolated cardiomyocytes gadolinium patch-clamp ionic currents
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