FIGURE 7.

LPI injection releases Ca²⁺ from acidic stores and sarcoplasmic reticulum in ventricular cardiomyocytes. A, averaged Ca²⁺ responses (n = 6) to LPI (1 μm) microinjection to ventricular myocytes incubated with Ca²⁺-free saline in the absence (top left panel) and presence of Ned-19 (inhibitor of lysosomal Ca²⁺ release, top right panel), xestospongin C (XeC), and heparin (Hep) (IP₃R blockers, bottom left panel) or ryanodine (Ry, RyR antagonist, bottom right panel). B, comparison of the [Ca²⁺]_i increases in response to intracellular administration of LPI (1 μm) in Ca²⁺ free saline in the absence and presence of the indicated antagonists. *, p < 0.05 compared with LPI.