Figure 9.

Ca²⁺ release from intracellular stores is involved in the DHPG effect on Kir currents. A, Plot of Kir inward currents as a function of time, showing that internal preperfusion of BAPTA (10 mm) to chelate intracellular Ca²⁺ eliminated fully the DHPG effect on Kir currents (n = 6). The representative current traces recorded at different time points are shown at the top as indicated. B, Plot of Kir inward currents as a function of time, showing that intracellular preinfusion of heparin (5 mg/ml) partially rescued the DHPG-induced inhibition in Kir currents (n = 5). The representative current traces (top) are taken from the time points as indicated. C, Plot of Kir inward currents as a function of time, showing that extracellular perfusion of caffeine (1 mm) induced a minor reduction in Kir currents with a long time delay (n = 6). The representative current traces are shown at the top. All the current amplitudes are normalized to the amplitude of the first evoked event.