Fig. 5. Interaction of cromakalin, glibenclamide and high-K⁺ treatments. In A, [Ca²⁺]_i oscillations (F_t/F_0(t=ib)) in a pacemaker region was measured in the presence of nifedipine (1 µM) and glibenclamide (1 µM) (a). Subsequently, 10 µM cromakalim was added (b: after 3 minutes). In B, after observing a control spontaneous [Ca²⁺]_i oscillations in the presence of 1 µM nifedipine (a), [Ca²⁺]_i oscillation traces (b) and (c) were obtained 3 and 5 minutes after application of cromakalim (10 µM), respectively. Subsequently, the extracellular K⁺ concentration was increased to 15.9 mM (from 5.9 mM) in the presence of cromakalim, and the trace (d) was obtained after 3 minutes.