Figure 3. KATP currents are detected in embryonic myocytes throughout development.
(A) Single channel KATP currents recorded in excised patches from 15 dpc WT (left) and 12 dpc Line 4 (right) ventricular myocytes. Current density histograms demonstrate 3.5–4 pA single channel current, corresponding to a 70–80 pS single channel conductance. (B) Whole cell voltage-clamp recordings of 12 dpc WT and 18 dpc Line 4 ventricular myocytes (Upper panels). Red: baseline current. Blue: Maximal KATP activation in presence of 100µM of Pinacidil. Black: current in presence of 10µM Glibenclamide and 100µM Pinacidil. (Lower panels) KATP current versus time (Pin=Pinacidil, Glib=Glibenclamide). (C) Whole cell basal (left) and peak (right) KATP current density in WT and Line 4 embryonic cardiomyocytes. Basal KATP current was significantly increased in Line 4 cardiomyocytes compared to early cardiac development WT cardiomyocytes (p<0.05) No difference was noted in peak KATP current between WT and line 4 cardiomyocytes.