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.