Assessment of LMC subcellular Ca ²⁺ oscillations in IALVs in the presence of the L-type blocker nifedipine. After recording Ca²⁺ videos using the paralytic wortmannin, the global and propagated Ca²⁺ flashes were blocked through the use of 1 μΜ nifedipine while the subcellular transients observed in diastole persist in IALVs from MyH11CreER^T2-GCaMP6f mice but are absent in Ip3r1ismKO-GCaMP6f mice (Videos 5 and 6). (A and B) Representative maximum projections of the lymphatic muscle Ca²⁺ signal and outline of individual lymphatic muscle cells for analysis. Scale bars are 50 μm. (C–F) Plot profiles and their respective space–time maps (E and F) of Ca²⁺ over time (x-axis) from a portion of the cells in A and B for IALVs from MyH11CreER^T2-GCaMP6f mice or Ip3r1ismKO-GCaMP6f mice, respectively. (G) Subcellular Ca²⁺ transients, puffs, and waves, were distinguishable in the vast majority of control MyH11CreER^T2-GCaMP6f LMCs but only occurred in a sparse number of LMCs in Ip3r1ismKO IALVs (*) and the number of analyzed cells that displayed Ca²⁺ transients in the presence of nifedipine was tabulated (G). n = 5 MyH11CreER^T2-GCaMP6f and n = 3 Ip3r1ismKO-GCaMP6f IALVs with mean and SEM shown.