Figure 7.

Stimulation of IP₃ production has a positive chronotropic effect on spontaneous Ca²⁺ transients in ESdCs A, phenylephrine (10 μm)-induced increase in Ca²⁺ transient frequency (n = 5) is reversed upon simultaneous superfusion with U73122 (1 μm; n = 2). B and C, ET-1 (100 nm) has a significant positive chronotropic effect (n = 4) on spontaneous Ca²⁺ transients that is reversed by superfusion with U73122 (B) (n = 2) or 2-APB (C) (n = 3). D, spatially averaged change of [Ca²⁺]_i induced by the application of ET-1 while spontaneous Ca²⁺ transients are suppressed by superfusion of the cells with tetracaine (1 mm) in Ca²⁺-free solution. E, ET-1 raised basal [Ca²⁺] by 15.8 ± 0.03% (n = 4) in comparison to the control in the presence of tetracaine plus Ca²⁺-free solution.