Myo-inositol rescues LiCl suppression of angiogenesis in vivo and in vitro. (A) Simplified schematic diagram of diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3) recycling to phosphatidylinositol-4,5-bisphosphate [PIP2; PI(4,5)P2], showing the step of myoinositol generation catalyzed by inositol monophosphatase (IMP) that is inhibited by lithium ions. CDS indicates CDP-DAG synthetase; PA, phosphatidic acid; PI, phosphatidylinositol; and PI4P, phosphatidylinositol-4-phosphate. (B) Myo-inositol rescues LiCL suppression of HUVEC invasion in vitro. HUVECs in in vitro angiogenesis assay are incubated in media with or without 10mM NaCl or LiCl and with or without exogenous myoinositol (same quantitation methods as shown in Figure 6). (C-G) Myo-inositol rescues LiCL suppression of HUVEC invasion in vivo. (C-F) Confocal images of trunk vessels in 30-hours postfertilization (hpf) Tg(fli-EGFP)^y1 zebrafish that were untreated (C), incubated with 200mM LiCl from 12 hpf zebrafish (D), received a yolk cell injection of myoinositol at the 1-cell stage (E), or received a yolk cell injection of myo-inositol and then were incubated with LiCl (F). Lateral views, anterior to the left. (G) Quantitation of the intersegmental vessel (ISV) phenotypes of zebrafish embryos in panels C-F. The bars show percentages of ISVs that have failed to sprout (blue), ISVs that have grown only up to the horizontal myoseptum half way up the trunk (red), and ISVs that have grown all the way to the dorsal trunk to form the dorsal longitudinal anastomotic vessel (yellow). The number (n = 50) of embryos counted is shown at the top of each column, with 10 trunk segments counted per embryo (same quantitation methods as shown in Figure 2). Scale bars = 100 μm (C-F).