Figure 3.

Endothelial cell growth and vascular permeability in flt-1^TK−/− homozygous mice. (A) Growth stimulatory activity of 100 ng/ml of mouse VEGF on primary sinusoidal endothelial cells derived from wild-type and flt-1^TK−/− mice by using the MTS assay. The assay was performed in triplicate for one mouse, and four or five mice for each type were used. The relative mean absorbances at 490 nm after stimulation with VEGF were shown in comparison with the mean absorbances without VEGF as control (100%). The average value for wild-type mice without VEGF was 0.31 OD₄₉₀, and that for flt-1^TK−/− homozygous mice was 0.45 OD₄₉₀. This slight difference in the basal levels of two types of mice appears mostly because of the technical difficulty for the preparation of mouse liver sinusoidal endothelial cells. (B) VEGF-dependent increase in vascular permeability of flt-1^TK−/− mice. −VEGF, with 2 ml of 1% BSA-PBS solution; +VEGF, with 200 ng of mouse VEGF in 2 ml of 1% BSA-PBS solution. The absorbances at 605 nm after stimulation with VEGF or with BSA alone (control) were indicated (see Materials and Methods).