Vascular endothelial growth factor-B-deficient mice display an atrial conduction defect

Background - Vascular endothelial growth factors (VEGFs) and their receptor s are essential regulators of vasculogenesis and angiogenesis in both embry os and adults. One of the factors with a still unknown physiological functi on is VEGF-B, which is expressed in many tissues, including the heart. Methods and Results - Mice carrying a targeted deletion in the VEGF-B gene were developed. In VEGF-B animals, no gross abnormalities were observed in organs that normally show high expression of VEGF-B, such as the heart, mus cle, and kidney. Analysis of heart function by ECG showed that adult VEGF-B -/- mice have an atrial conduction abnormality characterized by a prolonged PQ interval. VEGF- or basic fibroblast growth factor-induced corneal angio genesis was similar in normal and VEGF-B-/- mice. Conclusions - VEGF-B seems to be required for normal heart function in adul t animals but is not required for proper development of the cardiovascular system either during development or for angiogenesis in adults.