Different effects of gadolinium on I_KR, I_KS and I_K1 in guinea-pig isolated ventricular myocytes

Abstract

1. Using the whole cell configuration of the patch clamp technique, we studied the potential blocking effects of gadolinium (1 μM to 1 mM) on potassium currents: I_KR, I_KS and I_K1. The study was performed on guinea-pig isolated ventricular myocytes.

2. The background current, I_K1 was insensitive to Gd³⁺. Thus, we found that no obvious screening of surface charges was visible with concentrations of Gd³⁺ up to 100 μM.

3. By use of three different protocols: tail currents fitting, analysis of envelope of tails and electrophysiological dissection, we found that I_KR was the only component of I_K that was sensitive to Gd³⁺. The sensitivity was apparently different depending on the protocol used.

4. Comparison of the results obtained with the different protocols revealed that the rapid component of I_KR is more sensitive to Gd³⁺ than the slow one.

5. Of the different protocols used to distinguish between I_KR and I_KS, the electrophysiological dissection seems to be the more accurate.

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