Acute VEGF effect on solute permeability of mammalian microvessels in vivo.

To investigate the effect of vascular endothelial growth factor (VEGF) on solute permeability of mammalian microvessels, we measured the apparent permeability (P) of various-sized solutes on the postcapillary venules of rat mesentery in vivo. Exposure to 1 nM VEGF transiently increased P from a mean of 1.4 (+/-0.11 SE, n = 17) to a peak of 2.8 (+/-0.28 SE) x 10(-5) cm/s, a 2.4-fold increase for small solute sodium fluorescein (Stokes radius 0.45 nm), from a mean of 0.44 (+/-0.05 SE, n = 16) to a peak of 1.5 (+/-0.19 SE) x 10(-)5 cm/s, a 3.6-fold increase for intermediate-sized solute alpha-lactalbumin (Stokes radius 2.01 nm), from a mean of 0.049 (+/-0.0032 SE, n = 16) to a peak of 0.36 (+/-0.032 SE) x 10(-5) cm/s, a 7.9-fold increase for large solute bovine serum albumin (Stokes radius 3.55 nm), within 30 s. In approximately 2 min, all increased P returned to the baseline values. The response pattern of P to VEGF and the ratios of the peak to control values for rat mesenteric microvessels are similar to those of frog mesenteric microvessels [Am. J. Physiol.: Heart Circ. Physiol. 284 (2003) H2124]. Instead of considerable heterogeneity in the frog mesenteric microvessels, the acute response to 1 nM VEGF is homogeneous in the rat mesenteric microvessels.