Figure 3. VPAC1 activation releases Ca²⁺ from IP₃-sensitive Ca²⁺ stores in cardiac vagal neurons of nucleus ambiguus.

A, Characteristic increases in [Ca²⁺]_i produced by VPAC1 agonist (100 nM) in Ca²⁺-free saline, in the absence and presence of lysosomal disruptor bafilomycin A1 (Baf), ryanodine receptor blocker ryanodine (Ry), IP₃R inhibitors xestospongin C (XeC) and 2-aminoethoxydiphenyl borate (2-APB). B, Comparison of the effects on [Ca²⁺]_i induced by treatments indicated in A, in cultured cardiac vagal neurons; *P < 0.05 as compared with VPAC1 agonist alone.